A/C not working?

Yep, it sounds like the compressor is starting to go out which depicts the pressure you have, I would confirm the compressor is the problem by doing a CAN scan. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

This is to rule out the AC control module. 9 times out of ten it will be the compressor here is how to replace it in the images below.

This video will help you vacuum down and recharge the unit:

https://youtu.be/4EqdrBVb0sY

Here are the capacities as well, remember the new compressor will have the oil already inside of it so don't add more unless you lose some in the replacement. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Ken L, thanks so much for your response, very helpful.

Just today I was watching a video where they solve a very similar issue replacing the Control valve of the AC and I was looking at that option first.

So, will that Can Scan tell me if the problem is the Control Valve or something else?

I had a plan to either just replace the control valve and see what happens or take it to a shop to try to get a diagnosis but I'm not sure how accurate and reliable those are or how much they cost. If this tool can check those things, I might buy it.

I will definitely report once I get answers.

thanks again

Sounds good, with today's car a CAN scan will help tell us the system or direction to go in. I do not see the control valve you speak of, can you upload an image or give me the video link?

well, my AC compressor seems to be Variable displacement compressor (clutchless) so watching a few videos they talk about how the control valve can make the compressor stop working and blow hot air. And as if it is something common on this kind of compressors.

https://www.youtube.com/watch?v=goHxpksdB1Y
https://www.youtube.com/watch?v=5dYGnFFmcHQ

funny how there bunch of videos that talk about the clutch of the compressor but few mentioning that some compressor don't use a clutch.

I will have it scan and see it that comes up, but I thought it will be a cheaper thing to do before buying a whole new compressor.

what do you think?

thanks a gain.

update.

Today I went to the Hyundai repair shop, they said $245 for diagnosis, and that there is no code scan for AC, that they have to do it physically. wow. Every day I am more confused.

debating if to just buy a new compressor or try the control valve and I guess take my chances.

Hello, I just wanted to add a little info here. Thats a lot to diagnose the system. And I don't see why the shop is not able to look at some live data from the AC Control Module. Especially on a 2017. Things such as the Evaporator temperature sensor, ambient temperature sensor, etc. It might not be setting any codes in the A/C (HVAC) module, but the live data still has value. From your pressure readings, 58 is high for the Low-pressure side and the 135 is low for High pressure side at 72. This shows that possibly too much refrigerant is flowing into the evaporator. You do have a variable swash plate compressor. Do the pressures even out when the system is static (not running)? It's a big deal with A/C work, it can be tough to make a call on a compressor when so many other components are involved. I think the dealership means (manually) just pulling things apart and seeing what they find.

The A/C system does have a Pressure transducer which is not an On Off switch, it's an actual pressure sensor which there should also be a live data PID for in the PCM or HVAC control module. I'd be interested in seeing if you can pull up some of these live data PIDs just to see what they are reading and if any of it matches your gauge readings. I assume these pressure readings are with AC on max and the Recirc button is On and try 1,500 RPMs. Also see if there is an Evaporator temperature sensor data PID.

But looking through some service info, just on pressure readings alone, it points more to an Expansion valve (TXV) stuck semi open/closed, or the Temperature sensor is reading incorrectly. Granted this is just going by pressure readings,
Normal would be around 30 PSI on the Low and 200 to 250 psi around 70f. That would be normal at 1,500 RPMs. You might try having the system evacuated, pulled into a vacuum and refilled. Not sure how accurate this chart is for R134A refrigerant. High side looks a little low on the chart, for 70f. But see about the scan tool live data if possible.

I hope this info helps somewhat, it would be terrible to replace the compressor and not resolve the issue.

hey, thanks for detailed response.

yeah. high price for diagnosing.

Yes, those reading were with the AC on at full blast. when off the temp is even.

By reading I thought the expansion valve was the problem but a friend who works on regular A/C thought it was the compressor, so by reading more my second thought was the control valve. I know.

Just bought a control valve, $50 now you made me think about buying an expansion valve as well...lol.

Well, at least I am learning.

so, that Can reader linked above will give me those reading?
trying to decide if I should invest on it $100.00

thanks again.

cool

Well, changing out the expansion valve is going to be a bigger job, it sounds like you have someone that's giving good advice, so that's a plus. As for the scan tool I thought you already had one. A basic OBD2 scan tool will only scan the engine computer unless stated otherwise. To access the HVAC module, you'll need a scan tool capable of that. The Link below is for a scan tool that is Bluetooth to your phone and works with an App. It's actually a great scan tool for $120. It will do actual bidirectional controls, full system scans of every module in the vehicle and a ton of functional options. If you're planning on trying to fix your own vehicles in the future, this is the way to go. This scan tool does more than my $500.00 Autel. You should have no problem accessing the HVAC module with this. You will be able to get into the manufacturer side of the diagnostic system as well as the OBD2 Global data. It will probably pull up codes you didn't even know were stored in other modules.

https://www.amazon.com/Thinkdiag2-Bidirectional-Diagnostic-Bluetooth5-0-Intelligent/dp/B09YRDGY3Z/ref=sr_1_1?m=A2MGOU7GTZSI2X&marketplaceID=ATVPDKIKX0DER&qid=1675504175&s=merchant-items&sr=1-1&ufe=app_do:amzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

hey, I got the think diag 2, arrived today. trying to figure out how to use it. any specific report you think I need to pull?

will be reading more.

I did tried one for A/C but it came with error, Fault in communication with Vehicle ECU.

I will try to attach an image.

ideas?

Thanks

I am so sorry to be going on and on about this. I am trying to figure this thing out as much as I can but not getting any clear answers from nowhere. I wrote to the think diag chat and they said: If ECU error shows when only accessing the AC System, please check if the modules and circuit work properly.

So, I run all the test I could find on the thinkdiag 2 scanner and all seem to be working well (except some airbag thing). my only issue is when trying the AC diagnose test it comes up with the error: Fault in Communicating with the vehicle ECU. and ask iffy car has this system, if its electrical system and if ignition switch is ON.

Have no idea if my car does have this system or if is electrical . so I searching online to try to get more clear but nothing yet.

My questions are:

if the scanner is working well with my car model or not?
if the error is valid?
if is valid then it looks like some cable, fuse, connection issue to the ECU?

so, no compressor, valves issue so far, mostly connection to ECU module. What do I need to check next? buy?

wow. This is not a simple thing I see. LOL. I thought that scanner was going to tell me something clearer. LOL.

Thanks again for any help.

I hope to get to the bottom of this.

peace

Hi Miami hot, sorry for the delay, this other post came up as spam due to our filters, I apologize for that. As for the Think Diag, did you run all the updates on it yet? I'm sure there are a bunch. Were you able to do a full system scan on the vehicle and see/or communicate with others? I will look up the HVAC control module info and get back to you asap.
Ok do you have Auto AC or Manual? Auto AC should be able to set a temperature in the vehicle and it should keep it there.
The vehicle does have an AC Control Module, so if you cannot communicate with it that might be the issue with the system, it might not even be turning on the compressor, or there might so other fault occurring. And yes, the Think Diag is a complicated scan tool, but all the advanced ones are. It's much better than just a global OBD2 code reader. You'll get the hang of it .
just verify you can read live data from any other module, newer more advanced scan tools will have the option to enter the Global OBD2 standard side or the Manufacturer side where it should scan for your VIN, show the correct vehicle and allow to enter into specific modules. So as long as you can get into the ECM, BCM, etc and read codes, check live data. The scan tool is working, they do need updates, some of my scan tools with have updates for different vehicles every week or so. But if you run the updates and still cannot communicate with it, we should check that it is getting power and ground.
Does your Blower motor come on?
From Hyundai, the 1st diagram shows what to look for if a leak is suspect, oil and possible frost on a line connections. 2nd is the Pressure relief valve seal on the compressor, that it is still intact. I know we might be dealing with a different issue here, I just wanted to put these out. Hyundai is pretty good with their service information.

Here is the 2 HVAC controls 3rd diagram, the top is a Manual System, the bottom is the Auto AC system. Both have different wiring setups so we need to know which one we're chasing.

Hey, so glad to hear from you. thanks so much.

I did an update on the Thinkdiag 2 and still get the same error. will try to answer as clear as possible.

-Yes, my car has manual AC controls, the nob for fan speed, nob for AC on, I will attach photo.

- yes, It ran all other diagnose test with not errors no a problem . ( I did see that as it was checking for all modules when it came to AC it said not detected)

- when I run just the AC diagnose test it comes with the error :Fault in communication with vehicle ECU. - confirm vehicle is armed with the system, etc.

so, my question is:

1- should my car be showing AC diagnose with this tool? is it equipped with it, electrical?
2- if it should then where is issue possible? fuses, cables, valves, relays? control module?

so, that was the error I got when diagnosing just the AC.

any ideas? I did updated the thinkdiag, a couple of times. It shows my car VIN, and does all other diagnoses with not problem, just the AC says error communication, or not detected.

Thanks so much.
Its slow but I am learning as well.

peace.

PD: I will check for the frosting or pressure valve, will let you know.

Okay, cool. nice work. It will show the HVAC (A/C control module) if it is communicating on the network. The fact that it is not can mean a few things. Either the module is down completely and not talking on the data network, the communications section of the module has failed, there is a break in the c-canbus network wiring (unlikely here), the module is not receiving a wake up signal (On/Start Input, On Input). I know this all sounds like a lot, but by checking some voltage readings at the hvac connector we can see what is missing, and try to get it back online if possible, or see if its something else effecting it. The data bus network in this vehicle is complicated. The 2 main networks we are concerned with are the "K-Line" and the "C-Canbus" networks. Even by 2017 things have advanced a lot.
So, the first thing I need you to do is scan the entire vehicle and write down any codes you find in any modules. Just to be sure there is no other module or input that doesn't look right.

Are you comfortable using a basic multimeter to check some voltage readings? It will only be 12volts DC or less. No biggie. There are a couple Joint Junction connectors that the C-canbus network wires run through and out to other modules, canbus is a 2 wire twisted pair, so I will try to find these junction blocks first.
I missed if the Blower Motor was working or not? I see the LEDs are working on the hvac module, but can you change speeds of the blower motor, or vents from Floor to Dash?

This 1st and 2nd diagrams are the wiring harness running through the Dash, to the left "View A" is where the JMB Joint Connector is, it's a white 8 pin connector. Diagram 4 shows pin 6 (blue wire) and pin 3(Red wire), they are the 2 wires (c-can bus) coming from the AC Control module. With the key Off. Check that this connector is not loose or corroded. We will start there since the AC module seems to be powered up, just no comms. We will take some voltage readings of the back of the A/C Control module itself if needed.
Also check the fuses in the 5th diagram. Let me know what you find. If communication comes back, then we know there is a pin fitment issue near that lower driver side dash area.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Good morning.

Yes, the HVAC control nobs are working well, blower good in all position, also the air switch, Feet/Face and defrost good, also the heater function is good.

just not cold air at all.

a bit weird right?

I will do a multimeter test and run codes again like you asked. will let you know and report back.

thanks again.

Okay, cool. Really, we just need to make sure the JMB connector with all the red and blue wires running into and though it is okay. If there's an actual wiring issue with the c-can and that module is the only one not talking, the wiring problem has to be either in that connector or at the back of the A/C Control module. It might be tough to find because I think it's on the back side of that (View A) fuse panel. This is the OEM (manufacturer) diagram and there are Can bus wires so you should be able to communicate with it. But I have seen where a module is powered up, but the communications section of it was not able to talk to a scan tool. Have you tried using the generic OBD2 scan with the ThinkDiag, instead of the manufacturer side? I have not used this scanner yet, so I don't know if they give the option at the beginning. On my Autel for example, When I plug in, I can select OBD2 or select Ford or GM and then scan for the VIN. Sometimes just using the OBD2 side is more generic, and you might see the module. It is a bit odd everything on the module seems to be working, but we dont know how this entire system works. On a recent Chevy the BCM failed, and I found that the rest of the modules in the vehicle will use the last known good data from the BCM to keep the vehicle operating. I have to look into the A/C module some more. I'll post the diagrams for getting to the back of the AC module when we need it. But check one thing, go into the PCM live data with the vehicle running and check for an A/C Pressure Transducer reading. It might just be labeled A/C Pressure, but that sensor is powered and monitored by the PCM not the A/C module, see if there is any reading for that data PID.

hello,

I made a whole reply including 8 images but don't see the reply now. If it disappears and you need me to redo it let me know please. here are attaching reports.

The reply was very long and detailed. lol I hope it shows up.

thanks again.

okay, maybe my previews long replied disappear. I try again.

My car is automatic.

I try diagnosing with the scan multiple times and still get the same situation. all test comes fine except I can't do AC diagnose . So, when I do a health report, I see the app checks for AC then it says Not equipped. I will add images. I did the all system diagnose, also the OBD and all seems fine. I couldn't find anywhere a test for the PCM live data, I will keep looking but I don't think I saw it anywhere.

Today I got light test and a multimeter, I did some fuse checking the ones marked in red did not have voltage.

- my car passenger mirror broke and I replaced it with a new one
- small lamp on top of of the plate on the rear is not connected.

I haven't figure out yet JMB connector and c-can bus is located to be able to test, but I keep trying to figure it out and let you know. I include a photo of my dash in case you can guide me better. tomorrow I might open the cover to the dash fuse and see if I can have better access .

in the front fuse box also in red not voltage.

thanks again.

Hello again.

This is my last test from today. I include photos.

My main question is:
Is the A/C supposed to show up in the diagnosis or not? I have doubts, tried to figure this out, even wrote to thinker chat but so far, no clear answer. so, I assume it is supposed to show up.

If it isn't, maybe a fault in communication with the ECU is true like the scan says.
but my low side reading idle is around 90 and when AC on at full blast moves down between 65-75 kind of looks like compressor is engaged and trying to compress. Is this right?

so, open up the fuse dash driver side and tried to get as deep as I could. I stopped because I wasn't sure if I should keep going and also had no more time. I add photos in case you can see something that I don't. Is that JMB connector anywhere in the picture? or need to remove more?

So, if I find that connector how to test with multimeter? put negative on metal for ground and positive on the pin or cable? Volt DC. will multimeter work or light test for this? I am really a beginner, doing some YouTube research as well.

I did try to look for PCM data but only found PCM data and I think it might be the same info you were asking. attaching photos.

Thanks again.
Have a great day and more later.

My brain gets really obsessed when I need to figure something out...can't stop. LOL

Thank you for your help.

That's the correct fuse panel in your first picture, but the joint connector JMB is on the back side just behind that large white connector on the middle right side. It should look like the 3rd diagram one. Also only has red and blue wires coming out of it. We just need to make sure there's no pin fitment issue there. It is also strange; your scan tool seems to pick up the A/C module but then saying not equipped. I see the module in OEM and aftermarket diagrams. What's your VIN number, let's look your vehicle up with that and see if it's different. And your A/C pressure on the Low side of 90 PSI is way too high. Your vehicle is a 1.6 liter, correct?
The JMB is just a joint connector, is probably not plugged into the fuse panel, it's just a plug where the canbus communication wires meet up and go out to other modules.
Also try not to use the A/C with pressures reaching that high, who knows what the High side pressures are reaching.

Okay, I went to a different location to look at wiring diagrams to see if there are any different built models, I came across 4 different builds of this same vehicle. The RB, RBI, RBr, and the HCi. They all have the same size engines, look identical, and list the same year. But there were no listings like this in All Data. I'm not sure if this is country to country type changes or builds, but 1 of them did come with a manual AC system that looks like it doesn't have any communication wiring.
These seem to be different generation vehicles but listed in mostly the same year.

Let's go with what we know for now. In the PCM live data, technically speaking, there should be a data PID with an AC Pressure reading or voltage. According to All Data service info the PCM is responsible for that. If there isn't data on that, there is nothing we can do about that. But the pressures should equal out pretty fast when the vehicle is turned off. If your friend has a set of gauges, can he evacuate the system for you and see how much Freon is present in the system? Most modern A/C machines will measure exactly how much comes out. You have about 100psi lower than it should be on the High side and a little more on the Low side than it should be, but not excessive.
Are you hearing the Air Mix door in the dash moving when you switch it from Cold to Hot, does it get to full heat? I found this system diagnostics to be pretty accurate. It's also for R134A.

Hello.

I am a bit busy these days, so I won't be able to do anything to the car until Thursday or Friday, just to let you know.

But while I wait, I have been thinking a lot about this whole AC system and how it works.
By asking myself what controls the AC system? I came across a link:
https://axleaddict.com/auto-repair/Variable-Displacement-Compressors

where it explains a lot about it. Talks of ICVC and ECVC, basically internally or externally controlled variable displacement compressor. (I wonder what is in my car or how to know).
So, my main question is with external controlled system the ECU is in charge of the compressor sing data from a few sensors, the internally seems to be controlled more by the refrigerant pressure so I assumed the ECU does not have total control here. I am off?

So, if ECU is not communicating with AC system, that means it's not receiving data from the sensors nor sending data to the compressor solenoid or control valve. Is this right?

So, maybe the compressor and other parts are fine? wondering in my head.

anyways. I re-read your responses and saw the links. I think I will buy the vacuum pump you linked in your response.
I have a friend that works Acs but for house Acs, he had the gauges, when we talked about replacing the compressor, he said he could pass the refrigerant to his car and then put if back when the job was done. is this a crazy idea? in your video you put the refrigerant back but added not oil, I thought there was some oil that need it to be added when refilling a system, is that wrong?

anyways, just sharing some internal thinking while I wait to keep diagnosing what you recommended .

Thanks, and have a good day.

I would first do a CAN scan because it will cover the HVAC system and I would test the voltage at the compressor, if you remove the wiring connector it should show 12 volts at first start up. (Put the voltmeter in place of the compressor). Also, I have included the HVAC wiring diagrams so you can see how the system works. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is a guide to help you double check the pressures:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Check the power and ground of the HVAC control head.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Hello again.

The last reply was a bit strange because it sounded like a new person or maybe I forgot the previews replies. all good.

Today I did a couple of things.

tested the compressor switch plug.

so, I did it two ways, connecting the negative of the meter to the ground and the positive of the meter to the live pin and also, I did it putting the negative of the meter to the negative of the battery and the positive of the meter to the live pin of the plug. The volts I got were:

when car is off, I got around 0.14 to 1.8 volts on the live pin.
when car was on but A/C off, I got around 12 to 12,87 volts on the live pin.
when car was on, and A/C on, I got 12.75 to 12,80 volts on the live pin.

what does it mean? I thought there should be no volts if the A/C is off. what does this reading mean?

I also tried to get to the JMB connector, it was tough getting to it, but I think I found it. the issue is that to get better access I will have to remove the whole fuse board and it seems very messy and complex, but I did get to it, the issue was that because I unplugged everything that was connected to the front of the fuse box the power of the car was completely off so I could no do any volt test since there was no power in the entire vehicle. so I just looked at it and it looked fine. not sure I get any deeper into that area, what do you think? I attached images.

hope to hear from you
thanks again

I there any other valve or switch I can test?
I tried to look for the compressor control valve but could not see it, I think I have to get under the car. if there is any other test I can do please let me know.

Thanks

Did you do a CAN scan? This will tell us what is wrong with the system instantly. Here is the location of the high-pressure switch in case you need it.

That connector with the red and blue wires to it are the canbus high and low communications wires, as long as the connector cover and pins to it are tight, that's good, with it plugged back in do you still have no communication with HVAC module?

If not, then we will check powers and grounds at the back of the module. If you have voltage on the feed pin at the back of the AC compressor connector, that's fine,
Looking through other "Verified Repairs" another Technician ran into this same exact issue with a Manual AC system. He had no communication with the HVAC control module, replaced it and still had no comms, it was verified the correct amount of Freon was in the system, his repair was finally replacing the compressor and that took care of the issue. The ecm seems to be responsible for the AC Pressure transducer and control of the compressor, even though the wiring diagrams show things differently.
This is the procedure for testing the 3 wire AC pressure transducer. You will have to do the voltage calculation highlighted; I believe you had 158psi correct? So (voltage= 0.00878835 x pressure (158) + 0.5= 1.88volts roughly on pin #2(signal pin) and pin# 1 Ground). If you have a voltage signal that correlates to the high pressure reading, then the AC pressure transducer is ok.
If the pressure is incorrect or the temperature is too high the ECM will shut down the compressor. So, you can do a couple things here. You can take it somewhere and have them evacuate the Freon and measure how much is in there and see if it's correct. (Which I recommend before replacing the compressor). There is also a Technical Service Bulletin on this compressor operation, but it looks to be more for a shop or dealership testing setup, some of these compressors have an external control valve (ECV). Under this TSB though, they are able to get pressure readings with the GDS which is going to be their factory scan tool. You can try looking under the Body Control Module and see if there are any data PIDs for AC pressure under that module. But yours is a clutch-less variable compressor. The TSB requires a special test kit made by Bosch. It might be that the factory scan tool is needed to access the control module, some of the newer systems, manufacturers are limiting access with aftermarket scan tools, I have heard this is becoming an issue, I'm going to post to other technicians and see if the manual A/C system doesn't use communications with scan tools for whatever reasons. In the meantime, diagrams 4 and 5 show how to access the back of the AC Control head unit. We can verify there is power and ground for it and see if there are any canbus (Blue and Red) wires on pins 27 and 28. You should be able to get an average voltage reading if there is network activity on those wires.

There should be an AC Request data PID in the PCM data

Ok I found the problem; the wiring diagrams are incorrect. The Manual AC controller does not have canbus or K line communications at all. Only the Auto A/C Controller does, that's why it's not coming up on your scan tool. Diagrams 6,7 are the Manual Control Head and the connector pinout, diagrams 8,9 are the Auto AC Controller, you'll notice in the pinout (Connector B, pins 6-K line, 7 CANbus Low, 8 CANbus High,) those are the communications pins, the K line is for scan tool communications, I don't know why the correct module and connector diagrams were so difficult to find and why they are so incorrect. But this explains the scan tool issues.
Diagram 10 was the suggested testing process from another tech that knows this system well.

hello.

I tried to get to the High-pressure switch, and it was so difficult since it is facing down. I managed to remove the plug after a lot of work trying to get my arm through the small space to get access. but to test the pins that are on the actual switch I will have to get access from below and I am not sure I will be able to.

so, I was thinking I will just buy a compressor and take my chances. but also thought I could buy the high-pressure switch and try to see if that will solve the issue. Do you know if my model car pressure switch has a closing valve? meaning, do I have to empty the AC to replace, or can I replace without empty system?

one more question. hope is okay.

Is there a way to bypass the high-pressure switch to see if compressor will start? I know I shouldn't but I am thinking as a short time test.

Yes, the refrigerant needs to be recovered from the system to replace the pressure sensor.
Were you not able to find any Pressure Transducer data PID? I was looking over the PCM wiring diagrams and the Pressure transducer's signal wire into the PCM is labelled APT Sig. So that is your AC High pressure line signal. I thought it might be listed under something different and that's why it was difficult to find.
It shares are Reference voltage feed with the Fuel Rail pressure sensor, so that is most likely going to be a 5volt Ref as with other sensors. But at least now you should be able to find it in the list of engine data.
But since you have to recover the refrigerant anyways, have them measure exactly how much comes out, shops that do AC work will have a recovery machine that can do that, and since they are taking the Freon out, you still own that Freon, so if it is full to the proper amount, they should only charge you the 30min or so it takes to recover it and then recharge it after the repair.
A caution, if you do replace the compressor, some come already filled with the correct amount of oil and some do not. The service info explains all this,

And you're sure you have a variable clutch-less compressor? Take look at the 3rd diagram below, its shows a clutch-less compressor with a sheared off torque limiter. The other odd thing here is that in all this TSB information, they constantly say to check the system Status of HVAC system and AC compressor using the GDS. But one wiring connector for the Manual System shows no communications pins.
You mentioned the compressor is spinning continuously, so check that center bolt before going ahead, I have the instructions for replacing the compressor for you already but see if that limiter sheared off. And look for the APT sig in the PCM live data.

Hi,

It's been a while since I wrote here. I was super busy with work.

So, I replaced the AC compressor with a new original compressor from Hyundai.

The car started to blow cold air and it felt nice and cold after installation, but a few hours later as I was driving the cold air was not as cold as it needed it to be. Since then, the car has been blowing cold air but very weak, if it is a cool day, you can feel it not so bad but if it's a hot day the cold air is too weak to cool the car at all.

So, it's a Hyundai 2017 accent hatchback. Before I replaced the compressor the low pressure was very high and the high was normal to a bit high. Now with the new compressor the low is good at 45-50 psi (haven't check the high. and at least it blows a little be of cold air, before it was nothing, so this is improved but still haven't solved it.

Do you guys have any ideas of what it could be? What can I work on to see if I fix this issue?

I didn't replace anything else besides the compressor.

Thanks a lot. it has been a hot Summer so far.

Hello, yes it has been awhile, just going over your folder from your last posts, can you get a reading of the high side as well, Just so you know Harbor Freight or AutoZone, Advanced Auto, etc., sells a gauge set that is not too expensive, around 70 dollars the last time I saw one there. It would be good to have a set if you're going to be working on your own vehicle.
That pressure seems to be staying very steady at 45psi. Which is perfect for around 80f. So, after the repair you only had real cold air for a few hours, and you didn't find any other locations that were leaking? no other seals were replaced except for the compressor, and you had the system vacuumed down correctly and it held a vacuum for 30minutes? or did a shop do the work?
One other thing, you're not having any blower motor issues with air flow, it's just not that cold again, is that what's happening?

Since we had so many issues with finding the correct service info on your vehicle last time, can I get the Vin number? I will use that to look up your vehicle instead of just the year and model like last time. I did post this case on the All Data community where other technicians can give their input on it and one comment stood out. He stated, if it's a manual A/C system there will be no communication with the HVAC controls, (which is something we spent a lot of time trying to figure out.) Next, he said, simply check the ECM data to see if the compressor command is On, (which it would be now since you have a new compressor.) He also did say there should be a data PID for the A/C Pressure reading from the pressure transducer which should be under the ECM data. But knowing what the High side pressure reading is would help, if the High side is lower than 130 on Max A/C at idle, then we know there is something else going on, such as a leak, or bad temperature sensor.

You're also getting good drainage below the vehicle for the Evaporator correct? There should be a drain hose hanging down under the vehicle usually on the passenger side that allows condensation to drain out of the Evap/HVAC case. Make sure it's draining, stick a piece of wire up in the tube if not. If the Evap ices up, the Evaporator Temperature sensor will cause the compressor relay power to be interrupted.

hey, so I found some time and my friend helped me out with gauges...here are some videos with the readings. I added a bit more Freon but still the same thing. a bit cool but only enough for when it is cloudy or at night.

my VIN is : VIN #: KMHCU5AE3HU356161

So, you have any idea what this could be? the high control valve? That was my next choice. but to be honest I am about to give up and call some A/C shop. compressor is new, but not yet working. blower works, just not cold enough.

Thanks for your help as always.

If you did the compressor replacement on your own but didn't pull the system into a vacuum and monitored for a leak, the system could have a leak anywhere, adding refrigerant now is not going to do anything, because there is air already in the system from a leak. You need to have an A/C machine to add the correct amount of ounces of refrigerant to get the system and pressure switches to work correctly. Someone needs to find where the leak is before vacuuming it down and refilling it. Read through this guide on vacuuming and refilling:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Hi,

I am not sure I understand your message. Do you think there is a leak? What makes you think there is a leak? Can you explain a bit please?

I changed the compressor and di a vacuum, not for 30 min though. wondering why you think there is a leak. The pressures seem fine right? I looked everywhere under the engine and saw no signs of a leak. I was just assuming that because the readings are normal that amount of freon was good.

I am so confused.

Sorry I didn't know you pulled the system into a vacuum, the pressures according to the gauge and temperature do seem correct, did you add refrigerant by the can, or did you use an A/C machine to add the correct amount of ounces? That would be my only concern. I actually have a refill can with me right here, and it holds 12 ounces. Now my truck holds a total of 30 ounces, so you can see it is by weight that the calculated amount is added.
Your car takes 14.8 ounces of R134A refrigerant +/- 0.88. Do you know how many cans you added? I'm going to look up the HVAC temperature mix door info as well.
It's difficult to tell with these new compressors, because you can't see them cycling on and off now.

ah okay. yes, I added a can and a bit more from a second can. until low pressure hit around 50 PSI. before the yellow mark.

What size can did you add? it should say on the bottom of the can Net WT. 12OZ or somewhere around there. The pressure looks a little low for the 83.5 degrees, you can see on the R134 chart below it should be up around 45-55psi.
This was the vehicle with the Manual A/C system that we couldn't communicate with the HVAC control module, correct?

Yes, manual A/C.

I used AC Pro 20oz. the video above where is a bit low, I added a bit more R134 after just to get it to the right pressure.

So, if both pressures are good, that means the car has the right amount of Freon, right?
The cold from A/C is very mild. What could be the issue here?

thanks

Does the pressures on each side equal out pretty quick once the vehicle is turned off? Not that the pressures are really showing a restriction though, does your compressor have an electrical plug located on the rear of the compressor? Just looking through service info here, there looks to be an External A/C compressor Solenoid (electrical control valve) and a Mechanical Control Valve that is internal to the compressor. Both change the swash plate angle which is what controls the pressure. Service info states that the electrical control valve is a pulse width modulated solenoid, at the driver side front of the engine. I assume that is working ok because you have around 250 psi on the high side.
Unless there is something going on with the temperature mix door, it is not fully moving open when on the full cold setting. Which is something we can't monitor with a scan too either because we can't communicate with the Manual system.
I did find the temperature mix door actuator which is on the side of the HVAC system box under the dash. It has a potentiometer just like a throttle position sensor, where it has a 5volt reference, signal wire and ground. And when switching the temperature control knob from hot to cold, there should be a change in voltage from that actuator. It should range from 0.5v to around 4.5v roughly as the door travels.
You brought up the control valves at the top of the page in your post, the electrical control valve is supposed to be controlled by the HVAC control module. I'm looking on All Data and on Mitchell1 now for service info and they are both the same. Both have the Manual A/C system showing can bus network wires, which yours isn't supposed to have. I believe the compressor works on both of those controls. The internal one is mechanical and moves the swash plate by pressure.
I've found the voltages for the Temp Control Actuator, it's pretty easy to test, granted you can get to the actuator. You just have to monitor the 0 to 5v signal while changing the temperature control. I think it's something to check, just to rule it out.

Below you can see its location, it should be on the passenger side under the dash, where the passengers left foot will be. It's a 5 wires connector to the actuator. I'm getting the testing diagrams for you to check that the mix door is moving fully to the hot position and the full cold position. Disregard the replacement section, we're just going to test the signal wire to the ground wire. See if you can locate the actuator. And I'll post the testing diagrams in a couple minutes.

The 8th diagram is the testing to see if the temperature door is moving to its full position. Hopefully you can find the actuator pretty easily. This service information on this vehicle has been difficult from the start.