A/c Hot At Idle

challengerpilot · June 20, 2008

I have a 2002 Yukon XL with the 5.3L flexfuel. Just rolled over 100,000 miles. During city and highway driving the a/c is ice cold. When in stop and go traffic or parked and idling the a/c starts getting warmer. You could feel the humidity change in the car. I live in Dallas and the outside temps are around 100F. I added a can of r134a and when I was done the guage was in the red at I think 60 or 70. I have changed the compressor belt. I also flushed the engine coolant because in stop and go traffic the engine temp was approaching 230. Any help would be appreciated. Thanks.

gabbypig · July 31, 2008

I had the same problem. The issue was not enough air getting thru the condenser up front. I installed a supplemental 10" electical fan in fornt of the condenser (just fits) and wired the relay to the compressor switch. I kept the fan cluch behind the radiator. Problem soved!

Norseman · June 20, 2008

I have a 2002 Yukon XL with the 5.3L flexfuel. Just rolled over 100,000 miles. During city and highway driving the a/c is ice cold. When in stop and go traffic or parked and idling the a/c starts getting warmer. You could feel the humidity change in the car. I live in Dallas and the outside temps are around 100F. I added a can of r134a and when I was done the guage was in the red at I think 60 or 70. I have changed the compressor belt. I also flushed the engine coolant because in stop and go traffic the engine temp was approaching 230. Any help would be appreciated. Thanks.

Looks to me like, you over charged that bitch!!!

Did you check the guage reading before you started pumping more 134 into it?

challengerpilot · June 20, 2008

I have a 2002 Yukon XL with the 5.3L flexfuel. Just rolled over 100,000 miles. During city and highway driving the a/c is ice cold. When in stop and go traffic or parked and idling the a/c starts getting warmer. You could feel the humidity change in the car. I live in Dallas and the outside temps are around 100F. I added a can of r134a and when I was done the guage was in the red at I think 60 or 70. I have changed the compressor belt. I also flushed the engine coolant because in stop and go traffic the engine temp was approaching 230. Any help would be appreciated. Thanks.

Looks to me like, you over charged that bitch!!!

Did you check the guage reading before you started pumping more 134 into it?

Yes. It was barely in the red when I hooked it up. The temp to pressure chart topped out at 90 degrees so at 100 degrees outside i figured it was okay to be a little in the red. I added about a can and the pressure did go up a little. I felt like it must need it since it was hot at idle. I guess I am not the sharpest tool in the shed Any thoughts?

Norseman · June 21, 2008

I have a 2002 Yukon XL with the 5.3L flexfuel. Just rolled over 100,000 miles. During city and highway driving the a/c is ice cold. When in stop and go traffic or parked and idling the a/c starts getting warmer. You could feel the humidity change in the car. I live in Dallas and the outside temps are around 100F. I added a can of r134a and when I was done the guage was in the red at I think 60 or 70. I have changed the compressor belt. I also flushed the engine coolant because in stop and go traffic the engine temp was approaching 230. Any help would be appreciated. Thanks.

Looks to me like, you over charged that bitch!!!

Did you check the guage reading before you started pumping more 134 into it?

Yes. It was barely in the red when I hooked it up. The temp to pressure chart topped out at 90 degrees so at 100 degrees outside i figured it was okay to be a little in the red. I added about a can and the pressure did go up a little. I felt like it must need it since it was hot at idle. I guess I am not the sharpest tool in the shed Any thoughts?

Hate to say it but, you may want to think about taking it to a A/C shop and have it checked out. I know that's not what you wanted to hear but, so you don't risk real damage to the system it would be a good idea to let a pro take a look.

Good luck!

minibike132 · August 2, 2008

There is a GM TSB for this problem w/ the a/c not functioning at or near idle speeds, it's a test that says to simply unplug the low pressure sensor and then "hotwiring" the plug w/ a jumper wire

Where did you find this bulliten? I can't find it applying to a C\K truck It is pretty common for a S\T (Envoy or Trailblazer) but I have not seen it for a C\K. We do have issues with alot of our pressure switches but other than the S\T issue it is usually a shorted sensor dragging the reference circuit low and causing all kinds of other problems (other than A\C issues, they usually cause an SES light from other sensors on the same 5V line loosing power). Could you post a bulliten# I hate when I miss one but we cant catch them all.

gad723 · June 25, 2008

hello challengerpilot, i have the same issue with my truck it is a 2003 5.3 flex fuel yukon with close to 90,000 miles. i live in Laredo, Texas so i know how hot it gets in Dallas. my truck does the same thing at idle or stop and go traffic it sucks but when i get to 20 miles or above or if a increas the rmp when parked the a/c gets super cold. I remember my truck didn’t have this problem before, it used to blow ice cubes when it was park or in stop and go traffic. I took it to an a/c repair shop where they told me it was the compressor and they wanted $700.00+ to fix it. I’m a pretty good DIY’er so I replace it my self did all the nine yards as for an proper steps. I got all the parts on ebay even the gauges and vacuum pump. Well guess what it does the same freaking thing, I even changed the fan clutch (the truck never got past 210 degrees before I changed it) for one that is engaged (heavy duty) at idle and disengaged at 1800 rpm. Well that also didn’t fix the problem. I have changed the low pressure sensor and the ambient temp sensor the a/c belt. Anyone please help the only option that I have left is to go to the dealer where I have called already and they think that the a/c parameter might be off, whatever that means. I just don’t what to pay for something that they are not even sure about!!!

Fortune50 · August 2, 2008

There is a GM TSB for this problem w/ the a/c not functioning at or near idle speeds, it's a test that says to simply unplug the low pressure sensor and then "hotwiring" the plug w/ a jumper wire

Where did you find this bulliten? I can't find it applying to a C\K truck It is pretty common for a S\T (Envoy or Trailblazer) but I have not seen it for a C\K. We do have issues with alot of our pressure switches but other than the S\T issue it is usually a shorted sensor dragging the reference circuit low and causing all kinds of other problems (other than A\C issues, they usually cause an SES light from other sensors on the same 5V line loosing power). Could you post a bulliten# I hate when I miss one but we cant catch them all.

It's out there, I think it's a bit of an older one. It does cover S/Ts, Escalades, Yukon/Tahoes, Sierras/Silverados, even Bravadas & H2s. I just read about it this summer. I believe the more accurate description is a "low pressure cycling switch". And it described the symptoms as the a/c compressor not running at times intermittently. I believe tapping on the switch was also to be performed to see if it frees up and then using a fused jumper to try and get the compressor to run.....

C & A s Dad · August 2, 2008

I have a 2002 Yukon XL with the 5.3L flexfuel. Just rolled over 100,000 miles. During city and highway driving the a/c is ice cold. When in stop and go traffic or parked and idling the a/c starts getting warmer. You could feel the humidity change in the car. I live in Dallas and the outside temps are around 100F. I added a can of r134a and when I was done the guage was in the red at I think 60 or 70. I have changed the compressor belt. I also flushed the engine coolant because in stop and go traffic the engine temp was approaching 230. Any help would be appreciated. Thanks.

Eventhough someone else tried the fan clutch and it did not help, I would suggest you look at yours. My 02 Yuk XL has ice cold air at idle and driving. If the fan clutch is working properly and the condensor and radiator are free from debris, the fan will pull small animals and children into the grille at idle.

Fortune50 · August 1, 2008

There is a GM TSB for this problem w/ the a/c not functioning at or near idle speeds, it's a test that says to simply unplug the low pressure sensor and then "hotwiring" the plug w/ a jumper wire. If the a/c is now cold all the time, then the problem is w/ the low pressure sensor (located in the accumulator). It's a simple unscrew the old one and screw in the new one deal, supposedly no need to evacuate the refrigerant...

minibike132 · August 1, 2008

Looks to me like, you over charged that bitch!!!

Did you check the guage reading before you started pumping more 134 into it?

X2 on this. You were looking at a static charge and that isn't always a good indicator of what is going on in the system. What do your running pressures look like? That and pumping more in without having an educated guess on how much PAG oil you might need is asking for compressor trouble down the road.

I had the same problem. The issue was not enough air getting thru the condenser up front. I installed a supplemental 10" electical fan in fornt of the condenser (just fits) and wired the relay to the compressor switch. I kept the fan cluch behind the radiator. Problem soved

The issue of air not getting through is very common but I've never needed to install a fan to fix that. It blew ice cubes before so an extra fan isn't necessary here, a proper operating system is. The most common problem on these trucks is debris buildup between the condensor and radiator. The cover is easily removed with the push rivets, then just hose er out. Hose off the front of the condensor while your at it, and if your feeling really anal you can buy a fin straightening tool for cheap. These trucks are designed with plenty of airflow for good A\C operation without add on fans.

I just don't what to pay for something that they are not even sure about!!!

Edit: I was going to go on about how you've already wasted a bunch of money and how you might have some of that in your pocket if you had someone qualified do it right the first time, but that always ends up in some "Dealers are morons and always trying to screw us" war.

But back to the OP, at the very least I would have the system evac and recharged just to know you have the proper amount of 134 in the system. Even if you find something that fixes you here you should still have the proper amount in the system, overcharges hurt compressors and thats not the cheapest part to sacrifice. After that some running gauge readings could help us point you in the right direction. If you decide to go it alone and post the readings here then give the readings with vehicle at idle, windows up, A/C obviously on and Recirculation on. Post minimum and maximum readings for both high and low sides and the temperature output of the vents. Also take note of any irratic needle fluctuation, the needles should flow smoothly in one direction till the compressor shuts off then there will be a sharp change but no fluttering should be seen.