1987 325e A/C Compressor Cycling Too Quick

[RBeard3447@xxxxxxx]

I just had my son's 325 converted over to R134a (expansion valve had gone 
south).  It will actually cool quite well, however the compressor cycles too 
frequently. Like OFF 10 seconds and ON 5 seconds.  

The power for the compressor clutch is being cycled from the dash as the 
dryer switches are not opening (multi-meter verifies this). My first suspect 
is the  bulb thermostat, but the guys at Nashville AutoHaus think it could be 
the electronic control module (though they've never had to replace one.

Something interesting in their BMW repair book (genuine BMW) though.  It 
shows a control line from the Motronic unit going to the A/C  control module 
for purposes of turning off the compressor if the engine is under load.  I 
had never heard of this.

So three possible culprits: 1.) bulb thermostat, 2.) A/C control module, 3.) 
Motronic ???

Has anybody had experince with this?  What happens is the compressor doesn't 
stay on long enough to really cool like it should.

Regards,

Ritchie K. Beard

ritchieb@domain.elided

------------------------------