AC Relay Stuck ON

[UmmScott]

In theory... if u had the pressure switches disconnected, no call for AC from the control head, had your power meter backprobed into the pin right on the PCM that provides either ground or power to the AC relay and you...indeed have either ground or power there...
Then that would be an internal issue with the PCM.

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[UmmScott]

Reason i say that..
Is disconnecting any AC pressure switch should kill any AC signal from the PCM regardless...

You could send that AC request signal all day long a million times and should not have the PCM command the relay on because its missing the inputs from the safety switches.
The way you're describing it sure sounds like the PCM is messed up somehow. Pressure switches disconnected but still having a command out to energize the AC clutch relay from the PCM = bad PCM. [emoji846][emoji106]

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[east302]

Reason i say that..
Is disconnecting any AC pressure switch should kill any AC signal from the PCM regardless...

You could send that AC request signal all day long a million times and should not have the PCM command the relay on because its missing the inputs from the safety switches.
The way you're describing it sure sounds like the PCM is messed up somehow. Pressure switches disconnected but still having a command out to energize the AC clutch relay from the PCM = bad PCM. [emoji846][emoji106]

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Agreed. Removing the high pressure switch should kill the signal from the dash panel. Does it still show voltage on green/white wire (circuit 762) with the switch disconnected? I cannot remember which one that is... the one on the back of the compressor or the one on top at the hose manifold.

 

[UmmScott]

Agreed. Removing the high pressure switch should kill the signal from the dash panel. Does it still show voltage on green/white wire (circuit 762) with the switch disconnected? I cannot remember which one that is... the one on the back of the compressor or the one on top at the hose manifold.

Thanks east302!
So it is a ground side switched relay and the PCM grounds the coil internally.

Something is probably failed in the PCM somehow.

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[liquify33]

Re-check the 0411 swap segments for AC?