Expert: autohelp - 8/22/2009

Question
In auto mode demanding cooling there is delay in compressor clutch engagement.  Sometimes a minute or even longer before the compressor starts.  Sometimes it just will not engage at all. High side is about 200 psi and low side runs about 37 after clutch engagement.  Static system pressure with ambient temperature of 100 degrees and engine bay hot is about 110 psi.  Service AC light on the panel is not illuminated.  When it is working vent temperatures are about 50 F and it cools the car very well.  This problem just came on all at once and gave no other indications of trouble.  High pressure sensor has been disconnected and the same symptoms persist, thought it may be giving an over pressure value and not allow compressor clutch power on.  The high pressure sensor put out a value of 1.4K ohms static and about 800 ohms under pressure (200 on gage). I have servicing capabilities but no recovery unit to do a thorough check of weight of charge but it does not seem to be low on R12 or leaking.  Thought I was fairly good at troubleshooting but this one has me stumped.

Answer
I know just the expert you need to e-mail as I am also a little stumped as to what it could be without personally doing some hands on testing of your system. The person that I am having you e-mail has more years of AC expertise than I do and I am sure that he can tell you what your problem is.

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