Air Conditioning Poor Cooling at Idle

[CaptainXL]

I realize this was discussed a bit on the OS but I would like to start another session here so people have it for future reference.

Basically what is going is that my 05 Envoy XL has poor AC performance at idle. When I drive it a ways over say 40 MPH the air conditioning gets cooler but not icy cold like it should. A few months ago I added two small cans of refrigerant according to the instructions on the can and brought it up into the green. The AC seemed fine for a while.

Recently around here it has been over 100 degrees and high humidity. I was sure that the AC would be just fine but it has once again reverted to the same symptoms of poor cooling at idle.

So today what I did was replace the fan clutch hoping that that would be the last item to blame. Obviously I am here and it still doesn't work correctly. I am currently at a loss as to whats going on. I would have thought that replacing the clutch would have solved the problem because so many people with EXT/XL's on the OS said that putting a new Dorman clutch fixed their problem. I am going to go check the pressure again and see what I can see. In the mean time does anyone have any suggestions before I send it in to have a certified HVAC tech take a look at it? Worst case scenario is that I have a leak somewhere but lets hope not. If it is a leak its relatively slow. Thanks!

 

[essaycho348]

does air come out of it quickly? could it be a clogged cabin filter?

or

what type of a/c recharge did you use? did it have stop leak in it?

 

[CaptainXL]

does air come out of it quickly? could it be a clogged cabin filter?

or

what type of a/c recharge did you use? did it have stop leak in it?

Air comes out pretty good from the vents. No I didn't use the stop leak variety of R134A.

I just checked the low side pressures again both static and while running and they agree with service manual specifications. Scratching my head some more...

Temp: 95F and 65% humidity
Low side Static: 100 psi
Low side Dynamic: 52 psi

View attachment 21704

Looks good to me.

 

[The_Roadie]

Did you have or get the 2005 PCM update designed to address that exact issue? Assuming it's the poor fan airflow on startup when the cabin is hot and the engine coolant is not.

If it's just poor performance all around by the AC system, and your accumulator is not icy cold, I think you need a pro to evacuate and check for leaks, then refill it precisely instead of guessing. Also check the lines going to the rear for corrosion.

Nobody left on the OS knows this stuff?

 

[CaptainXL]

Did you have or get the 2005 PCM update designed to address that exact issue? Assuming it's the poor fan airflow on startup when the cabin is hot and the engine coolant is not.

If it's just poor performance all around by the AC system, and your accumulator is not icy cold, I think you need a pro to evacuate and check for leaks, then refill it precisely instead of guessing. Also check the lines going to the rear for corrosion.

Nobody left on the OS knows this stuff?

Hey Bill. I don't have any leaks that I am aware of. I am a pro. Just don' have pro tools

The particular TSB you are referring to states

"For 2004 model year vehicles and older, update the
Powertrain Control Module (PCM) with a software calibration that was developed to improve
coolant temperature gauge readings."

So since I have a 2005 there is no upgrade needed to the PCM. A year ago I also checked to see which PCM calibration was needed for this and I hooked up my scan tool using the software and it said I already have the calibration applied. So the only piece of the puzzle I was missing was the updated fan clutch.

 

[RayVoy]

does air come out of it quickly? could it be a clogged cabin filter?

We don't have a cabin air filter, however, air flow could be restricted by debris in the blower duct.

Air comes out pretty good from the vents..

This may rule out debris in the ducts.

I just checked the low side pressures again both static and while running and they agree with service manual specifications.

Looks good to me.

Low pressure was my first thought, you seem to have ruled that out.


I wonder if the temp door is in the correct position, maybe a fault in the actuator.

Although, it sounds like air volume is the problem, not the air temp.

Try the recir button, does this improve the problem?

 

[CaptainXL]

We don't have a cabin air filter, however, air flow could be restricted by debris in the blower duct.

This may rule out debris in the ducts.



Low pressure was my first thought, you seem to have ruled that out.


I wonder if the temp door is in the correct position, maybe a fault in the actuator.

Although, it sounds like air volume is the problem, not the air temp.

Try the recir button, does this improve the problem?

I am sure it would help if the recirculate actuator wasnt broken. Still need to fix that.

I stopped and got 3 - 12oz cans of 134a and added them. Whoever serviced this trucks ac before did not take into consideration the extra volume for the rear evaporator. Will keep an eye on it.

 

[Sparky]

We don't have a cabin air filter, however, air flow could be restricted by debris in the blower duct.

I do

My AC is pretty wimpy and struggles when it is this hot outside, so the OP isn't alone.

 

[RayVoy]

My AC is pretty wimpy and struggles when it is this hot outside, so the OP isn't alone.

I had an Extended '05 that I bought in '06, the AC worked grand......until, I developed a small leak in the rear lines. I had them repaired, but it was never as cold as new.............then, the compressor bearing failed, and I replaced the compressor.
I don't know if there was a difference in the capacity of the new compressor, but it was NEVER as cold as it was when new.

 

[CaptainXL]

Drove it around this evening and the compressor kept kicking off due to high pressure presumably. So I checked the low side again and it was at 70 psi. According to my chart at 100F that is good. But I still have very little cool air coming out of the vents. Gonna get me a set of gauges at harbor freight to see if the compressor has kicked the bucket.

 

[The_Roadie]

Is your accumulator frosty? That's the first thing I feel when somebody says their AC is weak.

 

[Menthol]

Took mine in for an estimate today.....it will cost $1200 to fix. I've been suffering for years now. Leak on high side and low side, I was told a line near the fire wall has to be changed + there seems to be a leak at rear (EXT) and new drier. They said the have to fix front first the to see the rest of the issues. Mechanic said these fixes for the TB/Envoy runs about 1200. This was a reputable shop .........no I can fix it with stop leak shop. If I seal the back off it will be about $400 cheaper.

 

[CaptainXL]

Is your accumulator frosty? That's the first thing I feel when somebody says their AC is weak.

The accumulator and line is hot. It wasn't this morning. I also notice that the left two dash vents have hot air coming out more so than previously (seems to be getting worse). The right two dash vents on the passenger side are cool. The rear second and third row vents are cool. Looks like an actuator or blend door issue?

Not sure if this is related but when I set the dash vent to full hot there only seems to be a little air coming out. So I guess I should address this first.

Edit: Is the drivers side temp actuator a common issue?

 

[Mooseman]

Took mine in for an estimate today.....it will cost $1200 to fix. I've been suffering for years now. Leak on high side and low side, I was told a line near the fire wall has to be changed + there seems to be a leak at rear (EXT) and new drier. They said the have to fix front first the to see the rest of the issues. Mechanic said these fixes for the TB/Envoy runs about 1200. This was a reputable shop .........no I can fix it with stop leak shop. If I seal the back off it will be about $400 cheaper.

I have a leak in my front evaporator and my rear has been permanently disabled because I had to cut the lines to replace the rear heater core. eBay has a rear line block off kit to disable the rear system and good shops should be able to lock it. Those that have blocked it haven't missed the rear air. If you really want to keep the rear air, eBay also has rubber line kits to replace the hard lines but are a PITA to install. I say block off the rear.

A leak near the firewall? That's what I suspected at first and wound up being my evaporator. Have all the parts but removing the entire dashboard is not a fun thing.

 

[Mooseman]

The accumulator and line is hot. It wasn't this morning. I also notice that the left two dash vents have hot air coming out more so than previously (seems to be getting worse). The right two dash vents on the passenger side are cool. The rear second and third row vents are cool. Looks like an actuator or blend door issue?

Not sure if this is related but when I set the dash vent to full hot there only seems to be a little air coming out. So I guess I should address this first.

Edit: Is the drivers side temp actuator a common issue?

If it's hot then I would suspect that it's now overcharged. I agree with having it evacuated and refilled with the exact amount.

 

[CaptainXL]

If it's hot then I would suspect that it's now overcharged. I agree with having it evacuated and refilled with the exact amount.

Well it looks like I need to do that. I lost almost all of my pressure today so something is leaking. Gonna pickup some gauges and a vacuum pump and test for leaks. Its got to be the schrader valves because thats the only place I have been working around the past few days. We'll see.

 

[Mooseman]

Vacuum testing won't pinpoint where a leak is and if you suspect the schrader valve, then having the gauge/vacuum pump connected will stop the leak if there is one there. What you would need is a leak detector like this one: Electronic Freon and Halogen Leak Detector . I bought one and it really helped me find the leak in the evaporator.

 

[CaptainXL]

Vacuum testing won't pinpoint where a leak is and if you suspect the schrader valve, then having the gauge/vacuum pump connected will stop the leak if there is one there. What you would need is a leak detector like this one: Electronic Freon and Halogen Leak Detector . I bought one and it really helped me find the leak in the evaporator.

In the evaporator ? sure you don't mean condenser in front of the radiator ?

 

[Mooseman]

Yep. EVAPORATOR in the dash is leaking. It happens. Maybe wet crud got on it and rotted it out from the outside.

 

[CaptainXL]

Just an update. I went in and got it checked at a shop. They found excessive water vapor in the lines and a leaking high pressure switch. So everything has been fixed and my pressures are at 85F is 50 low and 200 high. Right were they should be. The mechanic said the pump is good and found no other issues.

I took it on a 250 mile drive to detroit today and it was awesome. I noticed the air was much colder after only a miles worth of driving. Both front vent blow out icy cold air. Thanks everyone for the help!

 

[Menthol]

Got mine fixed too, repair lines near firewall and rear line, new drier, new switch near drier. Vacuum and recharge system, nice and cold. Will be blocking rocks from hitting the line under by sheilding with corrugated plastic boards (like the ones they use on the lawn signs)
From this
http://i184.photobucket.com/albums/x157/Menthol_03/th_PassRearQuarter.jpg

To This
http://i184.photobucket.com/albums/x157/Menthol_03/th_DSCF0762.jpg
This runs from halfway above spare wheel

will do some more near the crossmember and under driver side

 

[Sparky]

Just an update. I went in and got it checked at a shop. They found excessive water vapor in the lines and a leaking high pressure switch. So everything has been fixed and my pressures are at 85F is 50 low and 200 high. Right were they should be. The mechanic said the pump is good and found no other issues.

I took it on a 250 mile drive to detroit today and it was awesome. I noticed the air was much colder after only a miles worth of driving. Both front vent blow out icy cold air. Thanks everyone for the help!

I might not want to know, but how much did that run you? I do think I might want to get mine checked at some point as it certainly isn't anywhere close to icy cold. Cool, yes, functional, mostly, but it does leave a lot to be desired on hotter days.

 

[CaptainXL]

I might not want to know, but how much did that run you? I do think I might want to get mine checked at some point as it certainly isn't anywhere close to icy cold. Cool, yes, functional, mostly, but it does leave a lot to be desired on hotter days.

It was $125 to replace the switch and $125 for the recharge. Labor was included.

 

[Royalwapiti]

I had the system vacuumed and re-charged earlier this summer. I have been reading about the AC woes of others because mine was doing what Captain's was. I studied the fan issue, mine was made in Oct 2005, so it was after the TSB. I looked at the clutch shim threads, and a whole lot of others. I was ready to tear into my clutch shims this weekend and if that doesn't do it then the compressor and accumulator. Then I thought "I am going to re-check everything. Because the system works when I get it fully charged, it just fizzles after a few weeks."

Suffice to say I put the manifold on and actually revved it to 1500 rpms, both pressures were low. I thought it was only the Low side that was low before. I put two cans in and it works like a charm. My mechanic put dye in earlier this year, I couldn't find any leaks. I added a can of Stop leak hoping that does it.

If stop leak doesn't do it, I might take it in again, but to a different mechanic, the one I used just likes to do gravy work and lacks creativity to do real troubleshooting like find a leak.

I find myself jumping to conclusions after reading these threads, thinking my issue is the same as someone else and I end up doing a lot of stuff unnecessarily. It can be costly.