A C Cutting off

[chipper]

I recall a topic on this forum a few weeks ago about A C cutting off on hot days & the answer to the problem was a pressure switch I think. Mine is now doing it at temps over 85F.Does anyone recall the fix as I can't find it in the search system?

[cowboywildbill]

Try checking the A/C relay in the fuse box under the hood. It might be the culprit.

[roger350]

I didn't see the old thread you are talking about, but if your AC cuts in and out intermittently, from cold to nothing, back to cold, try replacing the pressure switch that is located on the accumulator-(the cylindrical tank near the firewall). I forget if it is called a low/high pressure cycling switch, or what? But it is about a $2 part and takes 35 seconds to change. I believe, when the pressure is not within proper range, it cycles the compressor off. My old '90 Chevy went from freezing cold one day, to this on again off again syndrome. After a while it would stay off longer than most. I knew I didn't have a leak, because when it worked it was ice cold. It was this pressure cycling switch. After changing it out, everything was great, but I ended up having to replace it two years later again. I'm no AC man, but give it a try, it worked for me, and I don't think you have anything to lose.

[chipper]

Roger350 hit it right on the head. That switch was causing all the problems. The service mgr said he has replaced dozens of them, especially on 2003 models that came from the factory with the wrong one installed.Also there is a improved version out, part #8904-0362. :D

[jbplock]

I was having the same problem – lousy cooling when outside temps in the mid 80’s and above. I printed out the first few pages of the thread 03 Weak AC Solution (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=005185) that describes the 02-01-38-007A TSB. The warranty work performed as listed on my service invoice was as follows:

“Owner states AC will not cool when temp is above 80 degrees.
CAUSE: Intermittent open in pressure cycling switch (89040362)/ Air deflector not installed correctly. New calibration of Actuators and module reprogramming.”

The service writer also said they evacuated the system and recharged with 1.6lb of R134.

My A/C is working great now... :D

[wushaw]

Low pressure switch on the accumulator is the culprit.