A/C Blowing Warm in Town

[Hydrospec2001]

Hey y’all,

I’m new to the site and I’m really hoping somebody can help with this. I know there’s other posts based on the a/c blowing hot in town but I have strange circumstances that don’t really fall under the other posts I’ve read.

I have a 2002 Escalade and when I run down the freeway it blows cool. Between the front and rear units it cools of but not to the point I can take it off max. In town it is outside temperature hot as if it is not on and only the blower is working. My first thoughts were a bad fan clutch. I replaced it and it was the same. I checked the pressures and it appeared a little low on Freon so I bumped it back up. The current pressures were 50/250 between high and low. It didn’t make any difference. When I looked at the compressor it was engaged. I turned the a/c off and the clutch disengaged as it should. When I turned the a/c back on the compressor engaged. I did notice that the compressor does not seem to disengage when the a/c is on but it still blows hot.

Well I went to a shop to have it looked at and they told me it was low on Freon and my compressor was leaking out. Interesting. I told him I just serviced it and my pressures were 50/250. He told me that I only had 12oz of Freon in the system. WHAT??? Then why was my compressor engaged with 12oz of Freon. I’m not sure at what pressure the cycle switch shuts off and on but I wouldn’t think the compressor wouldn’t engage with it being only 12oz on a 43oz system. Anyway the mechanic told me I needed to replace the compressor, drier and the orfice costing me near 1200.00. I’m fully capable of doing the work and servicing it myself but has anybody else had an issue like this. I don’t want to throw money at a bunch of parts that I’m not sure will solve it. I could sure use some help.

 

[sumo]

As long as There’s charge in the system for the pressure switch to see, it will still allow the compressor to engage. Definitely your description sounds like a undercharged issue. What you could do is have the system evacuated and recharged with dye. Once it starts blowing warm again, you can take a UV light and track down the source of the leak. This will tell you if your mechanic was right with the diagnosis that he told you.
From there if it is a compressor, just replace it yourself and recharge it with cans from the auto store or use a professional ac certified shop for the recharge

 

[retiredsparky]

The important step that Ian mentioned above is to have dye added to the system. A UV flashlight is very cheap. Use it after running the AC for even a short time (15 minutes) in a darkened room or at night. You don't have to wait until the system is running warm. At 250 psi, it won't take long for the dye to leak out and show up. It has a fluorescent yellow/green color that is easy to spot, unless one of the evaporator coils is leaking.

Often the flexible rubber hoses develop a leak at the connection to the rigid tubing, or an o-ring has shrunk at a connection. Another common problem is that the compressor front bearing gets worn, causing the seal behind the clutch to leak. If a previous owner tightened the belt too much, the side loading will wear that bearing.

If a compressor is replaced, the recommended orifice and dryer replacement is correct. As internal wear occurs in the compressor, small particles can slowly clog the orifice, reducing flow and efficiency. The new dryer takes out any moisture that the vacuum pump doesn't remove. (Moisture reduces the efficiency.) Leave the vacuum pump valved off (and turned off) after pulling the specified vacuum reading overnight to verify that there are no further undetected leaks.
Larry

 

[Hydrospec2001]

Well I went ahead and swapped the compressor drier and orfice because no leaks were observed around the front of the compressor or the lines. Could the compressor bypass internally? I’m not sure. Turned out The compressor was the wrong compressor! I just bought the Escalade and when I got back to the house I was crawling around under it I noticed a pig tail plug dangling underneath. I looked for about 20 minutes but couldn’t find the connection for it. Well I removed the old compressor and it turned out it was supposed to plug into the back of it but the bad compressor had no place for it. I’m not sure what the rear plug does but I put it all back together after flushing out the lines and condensor, pulled a vacuum and charged it and now it’s blowing cold at idle and while driving. It seems to be sealed up and holding charge now too. Thanks for the advice y’all!

 

[petethepug]

Sounds like the compressor you pulled had a plug in the high pressure sensor on the back of the a/c comp’r. If there was a plug screwed in instead of the sensor, the tech should of swapped them out. Congrats on making nice work of things.


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