AC compressor clutch not getting power

[SuffolkD@aol.com]

Ben:  I'm NO A/C expert. 
But I'd guess there is a temp or WOT sensor that keeps the system from 
engaging.............Just an idea.
If you drive a Chevy Malibu at 70 MPH in second gear long enough, the A/C 
goes warm............... :-)  4000's had a "cut out switch"....WOT.

> From: "Ben Swann" <benswann at comcast.net>
> 
> Two '91 200Q20V sedans with apparantly the same problem.  The AC system has
> full charge -  approximately 90PSI static/35PSI low and 180 PSI high
> pressure side during operation and outside temp around 80 deg. F.  Climate
> control set to low and everything operates except for compressor clutch is
> not engaging.  Applying power directly to compressor engages clutch and
> system blows nice and cold.
> 
> I noticed on the one I was just working on that there was no relay in
> position number 6 where the fuse box cover indicates AC relay should be.
> Inserting relay makes no difference.
> 
> Any clues as to what is going on?  BTDT on common culprit(s)?
> 
> Ben
>