hello all,
so I am not getting any juice to the compressor.... here's what I have done so far. this is a conversion to 143A and so have flushed the system and replaced the compressor, the switch control unit (but it was a used one!! ) the temp switch for the aux fan, the low pressure switch, and the expansion valve under the dash. As some of you might know I am still trying to find the A/C compressor relay which is somewhere other than the fuse block on the drivers wheel well (must be something specific to the '85 300TD). I thought maybe it could also be the ETR valve so I pulled the glove box and bypassed the ETR valve circuitry and still nuthin, anyway so I was thinking as I do some research on where that relay is, it could also be something wrong witht the used switch control unit I got. everything works fine with the entire system except the compressor wont turn on. while I was bypassing the ETR switch I did some checks for power there and there is no power at the ETR switch, there is also no power at the pressure switch (neither side) so i am now questioning the switch control unit. so with the background said here's my question........ does anyone know how to test the pushbutton switch unit to see if it is actually sending out the power to the compressor?? thanks all for sticking with me on this. specifically I would like to know which terminal on the control unit I should be testing...

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Thanks! Scott
sdpettitt@yahoo.com