Formula94lt1

Well power at the switch was 10.6v. I forgot where to test the head unit at and cannot find the thread.

One thing that worries me is the fact that I found no volts at the freeze switch, I may have to go recheck that, as I found 10.6 at the a/c switch with the car not running but Zero at the freeze switch, but that was when the car was running...

I guess that could also mean that the switch itself is bad, how could I test this?

Speedtoys

*bump*

Mrmerlin

did you replace the AC relay switch that is controlled by the AC switch?? if you did then it may be miswired otherwise it probably is bad

Mrmerlin

read this found with a search of "ac relay"
https://rennlist.com/forums/928-foru...ight=ac+relay+

Speedtoys

Im 99% sure my relay is fine, fans come on with AC switch, AC switch lights up, nd on defrost the system blows on high fan.

I have about 45psi of R134 on the high and low side..but no compressor spinny uppy.

Will take the 12v feed of compressor to ground next in the next few days, if not tonight.

SQLGuy

Based on what are you so sure about the A/C head relay? The pair of contacts in it that typically burn up don't power the fans or the blower. They only feed power to the clutch (through the freeze and low pressure switches).

You should take a meter and check for 12V (relative to ground), first at that the clutch wire (near the air pump), then at the low pressure switch (near the receiver drier - I think it's the bottom one), then at the freeze switch (under splash guard between windshield and firewall). If you don't find 12V at any of these points, then the A/C head relay (see links earlier in this thread) is a very likely culprit.

Paul

dprantl

45psi on both low and high side when the compressor is not running means there is not enough refrigerant in the system. Depending on ambient temperatures, you should be seeing at least 75psi on both sides.

Dan
'91 928GT S/C 475hp/460lb.ft

SQLGuy

Probably true, but the low pressure switch is supposed to close at 2.2 bar (about 33psi).