What that tells you is that either the HVAC isnt comanding it on for some reason or there is a bad connection prior to the relay. (the fuse block gets replaced from time to time for failed terminals) On the upside your compressor is ok.

 

If Wheatley commands the compressor on with HPT and it comes on, that would narrow it down to the HVAC controls not sending the signal, correct? If it doesn't come on, that would be a bad connection somewhere? Am I oversimplifying?

 

Yea,, if he commands it on, and it turns on..
Then there might be a problem with the HVAC controls or a bad pressure sensor?

Should be able to check pins 85 or 86 for a signal?

 

Need to check this. Pin 87 from the PCM?

 

You need a tech 2 to definitively fix your problem in a minimal amount of time without just throwing parts at it. there are too many what if scenarios that could cause your problem.

 

You already cleared that up. Nonnieselman's last post was suggesting you check the other relay terminals for a signal from the HVAC controler.

 

I see, thanks

 

Woops.. should have mentioned that..

Pin 30 should have power
pin 87 should be outgoin power to the AC

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


Pin 85 should be ground
pin 86 should be signal

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


those could be backwards, its been awhile since i looked at a diagram.
so 30 and 87 can be swapped, same goes with 85 and 86.

30 or 87 should have 12v+, with the opposite goin to the AC Comp clutch

85 or 86 should be ground with the oppostie side 12+


on 85 and 86, if one is grounded and the other has 12v+ then it triggers and makes contact between 30 and 87.. so both sets can be swapped and it still works...


make since?

 

Yeah, I get it, I think. So by completing the circuit between 30 and 87, I've tested that one supplies power and the other runs uninterrupted to the compressor. Now I need to test that there is a ground and also voltage coming to trigger the relay. I'm guessing I need to bridge the low pressure switch again as I think that would prevent the trigger voltage.


When I have time, I am going to run it by Lloyd-TX's shop, which is actually only about 2 miles from me, and have him hook up a Tech2. I know it would have been easier to do that from day one, but I am a curious kind of guy and really enjoy learning how things work (and hopefully fixing it myself).

 

Yep,, completeing the circuit with a jumper from 30 to 87 your taking everying out of the system.
i think the pressure switchs are on the trigger side, not the power side.