A/C problem

Tiny
LAURENCE1
  • MEMBER
  • 2005 JEEP LIBERTY
  • 89,000 MILES
My a/c started blowing hot air on the way home from a long trip out of state. There was also a burning smell. I stopped at a 7-11 and a man there looked under the hood and said the compressor was locking up and it might need a new compressor but he said if I turned the a/c off I would probably be ok to make it the rest of the way home. I was afraid of breaking down so I stopped into a franchise auto shop but they were really busy and said they couldn't look at the car for several hours. As I was outside deciding what to do, one of the mechanics came out and I told him what the man at 7-11 had said. He looked under my hood for less than 2 minutes and said I needed a compressor. He did no other diagnostics whatsoever on my car, he went inside and ordered the part. A short while later, the part came and he took my car inside and installed it. I paid a lot of money and left. Two hours later, I stopped to get something to eat. I went inside and my wife stayed in the car while it was running. It was then that she noticed the a/c started to blow hot air and the burning smell returned. I popped the hood and the new compressor was locking up. We drove for a few minutes and then the car began to overheat. We stopped and turned the car off and let it cool for awhile. Then we started the car up and left the a/c off and drove home an hour away. The car didn't overheat when the a/c was off. The next day, I took it to a mechanic who said it had a bad radiator fan assembly. My question is: was the first mechanic wrong to not have done any diagnostics to inspect the a/c system thoroughly to determine if I really needed a new compressor or not. Is it possible to determine if I needed a new compressor by looking at it for less than two minutes? Thanks for your help.
Friday, August 31st, 2012 AT 4:09 AM

40 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Without any testings, it is not possible to know if the compressor is wrong.

Unless the compressor is tested to be seized do you require a new compressor. Other than that it could be the clutch that is faulty or wiring problem.

When the cooling fans don't work, the cooling efficiency of the compressor would be affected.
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Friday, August 31st, 2012 AT 4:28 AM
Tiny
TELISIA
  • MEMBER
  • 1 POST
  • JEEP LIBERTY
Until now the air worked fine. It has 113,000 miles on it. The air blows extremely hot air. I had it Freon put in it and it still doesn't work. Then someone told me it might be my air compressor. How do I know if its my air compressor?
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
If the system checks out full, run a jumper wire to the compressor and see if it runs if not. If the compressor doesn't start bypass the high pressure switch too, if it still dosent start make sure all fuses are good then swap out the compressor. This guide will help

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

and

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Please run down this guide and report back.
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
HEAVYDUTY
  • MEMBER
  • 60 POSTS
If someone added freon I would guess they checked the A/C compressor operation. Have someone pinch off one of the heater hoses near the firewall and see if the air gets colder. Possible water shut off or air diverter door problem then.
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
WOOLSEY
  • MEMBER
  • 3 POSTS
I had this problem and had to replace the compressor cost me $324.00 all set I love this site.
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
MIKEHUGHES
  • MEMBER
  • 1 POST
  • 2002 JEEP LIBERTY
Air Conditioning problem
2002 Jeep Liberty 6 cyl Four Wheel Drive Automatic 130k miles

AC not blowing cold air, compressor just keeps clicking on and off. What might be wrong and what is range of repair costs?
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
If the compressor is cycling quickly, chances are it is low on freon. I would estimate around 100.00 to have it recharged. However, I'm not sure of the average labor rate where you live so that could be a little off.
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Tuesday, July 9th, 2019 AT 3:12 PM (Merged)
Tiny
CCOURTRIGHT
  • MEMBER
  • 13 POSTS
  • 2002 JEEP LIBERTY
  • 140,000 MILES
When using AC for the first time this year, worked great for about 15 minutes then stopped blowing cold air. Turned the switch to vent. Turned back to AC after about 15 minutes and it worked again. Again it stopped working after about 15 minutes. Sometimes it will work for anywhere between 10 and 20 minutes. When turning the vehicle off and restarting, it works then too. Again for anywhere between 10 and 20 minutes. Each time, I turn the switch to vent and then back after a certain period of time. What would cause the AC to shut off after a certain period of time?
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Get the refregrant level checked it may be low, if so there will be a leak that needs attention, do not add refregrant your self as over charging is a bad as under charging the system.
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
RICK59
  • MEMBER
  • 4 POSTS
  • 2004 JEEP LIBERTY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 104,000 MILES
Air conditioning not blowing cold enough inside. Checked vitals and found the following.

Ambient 88°F

With A/C on high for 10 minutes
Clutch engages and compressor turns without unusual noise. (Maybe too quite)
Low Side PSI 63
Hi Side PSI 210
Center Vent Temp 70°F

Turned AC Off and got the following
Hi Side PSI 130
Center Vent Temp 105°F

The compressor is obviously doing some work.
Compressor Bad?
Orifice Bad?
Other?

Thanks for any help you can give me.

Thanks
Rick Hawkins
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
By these readings it sounds like the compressor is weak and needs to be replaced here is a guide to help walk you through the repairs.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Please run down this guide and report back.
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
RICK59
  • MEMBER
  • 4 POSTS
Low on charge?

Wouldn't the low pressure be below the normal of 35-40 psi not way over at 63 psi if the refrigerant was low?
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
That's why I asked about system beinging open and repairs. Low side is high due to moisture or faulty blend door allow heat to enter evaporator. High side to low either low charge or compressor fault. So has system been opened or repaired?
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
RICK59
  • MEMBER
  • 4 POSTS
System has not been opened or repaired during the two plus years I have owned the vehicle. Air conditioning worked great until the recent past.

Any easy way to check the blend door function?

Took a reading of the vent temp with the air off the other day and it was 105F even though the ambient was 88.
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Please add some 134A I believe you will see low side go down and high up
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
RICK59
  • MEMBER
  • 4 POSTS
I had originally added refrigerant, a whole can, and the suction pressure was still high. So then, thinking I had overcharged I let some out, now who knows how much refrigerant is in there.

So since the last poste I did a complete recharge on the system.
Followed all of the correct procedures, using a very good vacuum pump and high accuracy vacuum guage.
Actually weighed the refrigerant going in and the charge is about 10 grams short on an 650 gram charge. (I don't remember what the exact number was but I charged per the number under the hood)
The system now has the correct charge.
To diagnose the system I connected several temperature probes to the system lines.
The temperature probes were taped down on metal lines and insulated.
Following the system from the compressor.
The discharge line travels about 12 to 18 inches and enters the condenser.
The DISCHARGE PRESSURE port is in this span a few inches from the condenser inlet.
The CONDENSER INLET TEMPERATURE was taken a couple of inches from the condenser inlet.
The CONDENSER OUTLET TEMPERATURE was taken a couple of inches from the condenser outlet.
From here the line travels about 8 inches to the orifice tube.
The SUCTION PRESSURE port is a few inches after the orifice tube.
The SUCTION TEMPERATURE was taken adjacent to the SUCTION PRESSURE port.
From here the line travels (uninsulated) about 2.5 feet to the evaporator inlet.
The line exits the evaporator and goes directly into the suction accumulator.
The line out of the suction accumulator travels about 12-18 inches to the compressor.
The EVAPORATOR OUTLET TEMPERATURE was taken just after the suction accumulator.
The following are the readings taken after the recharge.
-At Idle
-Fan on high
-System running for 10 minutes or more
-Several sets of readings taken and remained constant.

DISCHARGE PRESSURE 225 psi
CONDENSER INLET TEMPERATURE 171 °F (About 32 ° Superheat)
CONDENSER OUTLET TEMPERATURE 120 °F (Good heat rejection across condenser)
SUCTION PRESSURE 64 psi (This is too high right? )
SUCTION TEMPERATURE 71 °F (Chart says says PSI should be 71 so maybe slight superheat here but maybe temp and/or pressure gage slightly off)
EVAPORATOR OUTLET TEMPERATURE 102 °F (This shows that the evaporator is absorbing heat)
CENTER VENT TEMPERATURE 76 °F (My Plymouth van was making 62 ° immediately prior in the same ambient conditions)
AMBIENT TEMP DIRECTLY IN FRONT OF THE CONDENSER 93 °F

Later I went out and took temperatures in three places.
1. Directly after the evaporator (which is directly before the accumulator)
2. Directly after the accumulator
3. Directly before the compressor
This showed about a 10 °F rise in this span which may indicate that the refrigerant is leaving the evaporator as a gas and picking up superheat along the way to the compressor.
The compressor is quiet and doesn't seem to make excess noise.

Sure would like to know for sure what is wrong with the system so I can replace the right thing the first time.

For what it's worth,
This system is somewhat different from my Plymouth Van which is as follows.
The compressor outlet goes into the condenser
From the condenser the line goes into some kind of small vessel. Possibly a drier.
From there the line goes into a TX valve which is directly before the evaporator. The high pressure port is located in this line after the condenser and before the TX valve.
The line then goes directly to the compressor with no accumulator. The suction port is in this span between the evaporator and the compressor.
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
I show a fixed Orfice tube not a TVX. Two possibilities for elevated Suction blend door not shutting allowing heater core to warm evap. so acess through glove box see diagram


https://www.2carpros.com/forum/automotive_pictures/198357_Graphic_526.jpg

see if motor operates from warm to cold. other but have not seen in CCOT is Orfice tube damaged not droping pressure entering EVAP. any TEMP differential befoe and after Orfice?
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
HLACEFIELD
  • MEMBER
  • 0 POST
I had this problem and had to get a new compressor cost me $340.00 all fixed I love this site.
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
JEEP7L
  • MEMBER
  • 2 POSTS
  • 2007 JEEP LIBERTY
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 78,000 MILES
My a/c only works when blowing from the bottom the top blows out warm what could be wrong with it?
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
You need to open it up and investigate the air blend/mix/mode actuators/vacuum operation and check the HVAC control module
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Tuesday, July 9th, 2019 AT 3:13 PM (Merged)

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