Roler

Summary to keep it short, following a few hours of diagnostics
AC clutch not engaging, did the following diagnostics on the relay and the low pressure switch (LPS)

With the low pressure switch connected:
Key ON or engine running. measuring at the AC clutch relay sockets: 86 has power, 85 has ground, jumping 30 &87: clutch engages (but no cold air)

With the lower pressure switch jumpered at the connector:
Key on (not running): power at socket 86 and ground at 85
Key in run/engine running: power at 86, ground at 85, aux fan comes on, clutched engaged the 1st time, but not on the 2nd test or the 3rd test

With the relay out and the LPS jumpered:
Key ON/or engine running: NO continuity in the LPS

With relay out and LPS jumpered:
key in RUN (ON): 86 has power, 85 has ground, jumped 30&87: clutch engages (no cold air)

Shortly pressing the low pressure service port shrader valve releases pressure, suggesting I have refrigerant (I don't have AC test gauges)
Tested the AC clutch relay with power probe and multimeter - it is doing all the right things


So my confusion here ( AC is not blowing cold air) re the following:
- no continuity at the LPS would suggest the LPS is faulty; however the PCM grounds at 85 with key ON , suggesting the PCM sees all the requirements and is happy to provide ground at 85 to 'activate' the coil on the AC clutch relay

- I measure NO continuity at the LPS (both without and with key ON or engine running) which suggest the LPS is faulty (or low in refrigerant, however pressure escapes the shrader valve when testing)-
how come the PCM still grounds 85 socket, which suggests the PCM is happy with the info it is getting from the LPS?

-With the relay out, I have power at 86 and ground at 85 and jumpering 30 and 87 engages the clutch- suggesting the AC relay is faulty while it tests perfectly fine with every single test on the relay (tested out of the vehicle)
It would suggest once in place, the relay is not functioning which would indicate a fault at the socket - but I have nothing suggesting this


I am a bit stumped at this - happy for any input!

Saudade

If you have one, hook up a manifold gauge. With the system off, both high and low side should read equal pressure. A "rule of thumb" says the measured pressure should be about ambient temp when the system is off and cold. You may hear some escape when you press the valve but there may not be enough to operate. Just like folks that press the fuel Schrader on the rail and think they have fuel pressure because it squirts a bit.

If you jump the clutch and compressor engages but it still blows warm air, you're likely low on refrigerant. I realize that may not address your issue/question, but if it's low, it needs recharging.

Roler

No I don't, that's why I mentioned I don't have them .

The shrader valve test was just to ensure I had at least sóme refrigerant in there- indeed no indication of enough pressure or not.
​​​ I thought that jumping the LPS would allow me to take it (low refrigerant) out of the equation during diagnostics.

Also, if the level was too low to operate it (and the low pressure switch would not have continuity ) why would the PCM provide ground (when it shouldn't)?

Roler

Giving this a little bump for some input