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AC problems

Tiny
PATCARCRV
  • MEMBER
  • 2009 HONDA CRV
  • 2.4L
  • 4 CYL
  • AWD
  • AUTOMATIC
  • 92,000 MILES
AC blowing hot air when in city traffic on an above 80 degree day. Later on the same day, when out of center city and on a highway, AC will blow cold air after an hour drive at 50 mph.
Saturday, September 6th, 2014 AT 2:40 AM

16 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
This sounds like the AC is low. Here is a video to help you see how to recharge the system and a guide as well:

https://youtu.be/uZrQCGwXfek

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Also, check the radiator cooling fans to make sure they are coming on.

Please run down these guides and report back

Cheers
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Saturday, September 6th, 2014 AT 4:17 AM
Tiny
PATCARCRV
  • MEMBER
  • 2 POSTS
I believe that you are correct that the fans are not working so I checked the fuses and they are okay. The fans are not seized so it could be the thermostats or some control relay? If it is something other than the fans, can you explain where the control parts are located so I can judge if I can repair myself?
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Sunday, September 7th, 2014 AT 7:42 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Here is the wiring diagrams for the fans and a guide to help check the wiring and relays:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

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

Here are the cooling fan relay locations as well and the wiring daigrams

Check out the diagrams (below). Please run some tests and get back to us.

Cheers
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Sunday, September 7th, 2014 AT 7:57 AM
Tiny
PROHOVIE
  • MEMBER
  • 0 POST
Thank you. I replaced the relay now the AC works great! Thanks for the post. I love this site.
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Tuesday, July 31st, 2018 AT 6:56 PM
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
  • 2007 HONDA CRV
  • 92,000 MILES
When it is hot outside (90+) and the A/C is worked hard, it starts blowing hot air suddenly. This most often occurs when the max A/C button is selected but not always.

I have run the diagnostics by pressing the recirculate and rear defrost buttons, but no code is shown.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
They have been having a lot of problems with failed compressor relays on those recently. I would try swapping the relay with a like relay from something non-critical like the horn.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
Which relay? I went do do this and found 3-4 relays that appeared to be A/C related and none for the horn.

Also, to complete the diagnostics I mentioned earlier is a code scanner needed? I was looking at the dash control panel for any codes to flash.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
I swapped the A/C compressor clutch relay with the rear window defogger relay and the A/C condenser fan relay with the fan control relay.

The problem appears to be resolved but I do not have the heat that caused previous failures. I will update later if this does not work.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
You need to replace those relay/s with new ones now.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
Relays were not the problem. It started up again today. I tried checking the low side pressure, but the compressor wouldn't kick in so I know the reading is not correct.

I bought a can of r-134a with a gauge to check the levels, but the gauge does not return to zero after being disconnected. So I am not sure if it can be trusted once the problem goes away so the compressor will kick in.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
You do not want to be arbitrarily dumping refrigerant in there. That system requires a very specific weight of refrigerant. If you put too much, you can destroy a $1,000.00 compressor and a lot more. That needs to be checked by a professional.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
RFETESTED
  • MEMBER
  • 1 POST
I too am having this problem started about a month ago. Mine seems to work fine unless it has run for a couple hours and you stop for gas or something then when you restart the car the A/C will only blow hot air for thirty minutes or so. If I leave it off for thirty minutes or so it usually (so far) starts blowing cool air again.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Ensure the cooling coil is not frosted. That would occur when air leaks into cabin with thermostat set to minimum.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
Yesterday the compressor started working again and I could tell the true pressure. The gauge I was using has a high pressure when the compressor is not on because it was also charged by the can that is connected. I found there was only around 10 lbs of refrigerant so I added a fair amount. When I ran out the system was around 30-35 pounds and only 5-10 lbs below the optimal charge for the temperature.

Even with the new refrigerant, the system ran for a minute and then the compressor started cycling on and off rapidly, spinning up and stopping once full speed was reached. I tried to see if driving would help as the engine speed seemed to be affected. After driving two miles I heard what sounded to be a long release of air, similar to a truck with air brakes. I shut the AC down until today.

Today the compressor ran fine for the first minute then started cycling again. I was able to ascertain the refrigerant pressure is at 25 lbs so apparently I did not lose much yesterday.

I understand a mechanic will need to fix the leak, but I need to save every penny possible. Can I continue to diagnose the compressor? Is there a switch controlling the compressor that may have failed? I do not think there is time for the cooling coil to become frosted and it is not that hot today.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
TANIKIR
  • MEMBER
  • 6 POSTS
I am wondering if the schrader valves need tightening. Could that cause the release?
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If pressure is going down, it means there is a leakage somewhere and you need to perform test to find out. Speculating is not going to solve the problem. If you keep putting in gas, it is going to cost you a lot of money for nothing. You would also be contributing to pullution of the atmosphere.

Without specialized equipment and proper diagnostics, you should not be attempting A/C repairs, especially if it involves depletion of Freon.

For A/C diagnostics, you need to at least know the high and low pressure. Only one pressure reading is not going to tell you anything.
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Tuesday, July 31st, 2018 AT 6:57 PM (Merged)

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