Ah ok.. just following orders lol

What's the next step then? I'm lost

Thanks!

 

Ok, I found how to check DTCs and...

Nothing.. everything there is working, just no power to the compressor.

So, what next? Put in a manual switch to turn it on and off while driving?

I'm almost serious! lol



Found an 06 diagnosis and if compressor wont run, but fans do, the only thing I havent checked on its list is "•Check compressor thermal limiter"

Where is it, and how do I check it??

Thanks!

 

Ok, I didn't know what else to do, so I got a long test lead and checked for an open between #3 on the relay and A27.. I got about 2ohms, so its getting thru.

I double checked for ground with AC on, and with just key on, I get nothing or a -1 reading on meter. With car running it gives -1938 ohms!?

Is the PCM bad or is it missing a signal from something else??

Thanks!

 

How did you check for HVAC codes?

 

Held the vent down and hit def 5 times fast and it went thru a diag and came back with no codes.

I pulled a plug and did it and got a code, so I know that part worked at least.

 

Some of your electrical tests are strange to me. Also you got the compressor to run when testing for ground.

Does your volt meter have two spots where you can plug in the red volt meter lead? If yes, which one is it plugged into?

 

I have the meterS correct. I'm not great at diagnosis, but I did take electronics way back in high school.

I mis-spoke about the ground WHILE testing, I should have said, I could ground the backprobe and it would run. (the other threads OP could get it to run while testing he said tho)

The Ohms I get from A27 are like I've never seen. the digital meter goes either blank , or gives a -2000 something if I switch the leads.. Never seen that before.. The Analog one does similar. It pegs either PAST infinity, or goes UNDER 0 setting. SO, peg far left, or far right!

And I have it set for 1000ohms (lower does not matter either) NOT Volts, like one might think would show this behavior. lol.

Really, I just need to know how to test the pressure switch AT the PCM, or anything else going there, to make sure its getting all its signals, and if so, then the PCM needs to be replaced. If not, then I track down that sensor.

Thanks! This is a lil bugger for sure.

 

The pressure switch is a binary switch w/ Low Pressure and High Pressure switches. See attached diagram. With AC Off, switch A should be closed and switch B should be open.

Sorry for earlier confusion on L4 diagram.

good luck

 

Other than the PCM, issue can also be possibly due to either the:

• Heater control panel (part of the audio-HVAC display module)
• multiplex integrated control unit (micu is part of driver’s under-dash fuse/relay box), or
• wiring between the heater control panel--> micu --> ECM/PCM.

Faulty A/C pressure switch (staying open) will cause the relay control module to send a signal through the multiplex integrated control system to the ECM/PCM. Upon receiving the open circuit signal, the ECM/PCM turns off the A/C compressor clutch.

How system works:
The A/C button at the heater control panel must be pressed to activate the A/C system. With the ignition switch in ON (II), the heater control panel grounds the A/C ON input of the ECM/PCM through the multiplex integrated control system and the A/C pressure switch. The ECM/PCM then grounds the A/C compressor clutch relay coil. This energizes the coil, which closes the relay contacts and provides battery voltage through fuse 12 to the A/C compressor clutch. The clutch then engages and begins turning the compressor.

The A/C pressure switch is located in the condenser outlet line where refrigerant is in a high temperature/high pressure liquid state. The switch
will sense abnormally high or low pressure, and open the circuit. When the circuit is open, the relay control module sends a signal through the multiplex integrated control system to the ECM/PCM. Upon receiving the open circuit signal, the ECM/PCM turns off the A/C compressor clutch.

 

Thanks for the diagrams. I will look them over and see if I can find something open that shouldn't be..

The pressure switch is closed 1-4 and open 2-3 when I tested it at the condenser. Gauges read 100lbs each side, unless I ground or jump compressor, then it drops to about 20lbs low side, as it only has one can of freon in it.. Once its working, I will put the rest of the 19oz in.

The buttons all work, and I think the clutch wont engage if the AC buttons are off, I'll check it again..

But if the pressure signal IS getting to the PCM, then the PCM is prob blown?

I can totally see the previous owner or one of his friends trying to jump it when the old clutch blew out and frying the PCM.

Eh.. thanks!

Where is "Relay Module 1"? maybe that's out, or the blu/red is open to it? (or should I check continuity from the switch to A26 and A15?)