A/C Clutch not engaging
 

Hello, I have a 2011 Nismo that a/c clutch won't engage when a/c selected. The light in the button turns on, and my scanner says the control is sending signal to the IPDM.
I can run 12v to the compressor and clutch will pull and a/c runs.
I am thinking its either the pressure switch or a/c relay, which I think is buried in the IPDM?
I have checked all the fuses and they are good.

Any thoughts before I go to dealer for diagnosis?

Pull the IPDM, find the A/C clutch relay (you can download the FSM - link in my sig - if you have problems locating it). Hold you finger on the relay and have someone cycle the A/C on and off. You should be able to feel a "click" when the relay de/energizes. No click = bad relay.

How did you check the fuse(s)? A visual check is not always accurate. Use a meter.

Check for voltage at the A/C clutch. If you have power when called for, the relay is OK and the clutch is bad.

Wiring diagrams, connector pin outs, system operation description, etc are in above-mentioned FSM.

Thanks, I have the FSM but there is no where that I can find that shows the location of the A/C relay. I have google'd as well with no real answers. I think it is buried in the back side of the IPDM, and is not meant to be serviced.

I checked the fuses with meter.

I don't have voltage at the clutch, or pin 49 in the IPDM, which is the clutch wire.

The clutch and compressor works, as it will engage and run when I put the 12v from the heated seats spot in the relay box directly to it.

I may pull the IPDM and try to open it up again. I see they only run about $80 on Ebay if I screw it up.

Jump the high/low pressure switch and see if that corrects your issue. If that works, you have a bad switch or a low charge.

The pressure sensor plug has 3 wires, not sure which 2 to jump. I don't want to wreck anything electronic wise. I do know which one is the 5v reference wire, guess it would be that one to the one back to ECM?

Any ideas on which wires to jump on pressure switch?

I'm glad you didn't try to jump any wires... It isn't a switch, but a pressure sensor.

I suspect your A/C refrigerant is low and the ECU isn't turning on the A/C clutch to prevent damage. If the pressure sensor detects less than 17 psi or more than 452 psi, the ECU will not turn on the compressor.

If your scan tool has advanced diagnostics, it can show you the voltage, or use a meter to check. It should be between 1-4 volts.

The center wire is the 5 volt sensor output. The outside wires are ground and 5 volts. Use a meter to determine the polarity and check the voltage between the sensor ground and the centre wire.

I'll plug it in and take a look.

I had the system evac'd and refilled and and compressor still would not start.

I have 5v on the outside to outside wires checked with meter.

I also ran the data on my Snap On Solus Ultra scan tool and it does show the A/C Comp request signal being on, and the light on the A/C control button is on as well.

Ah, they changed them up. Time to get out a gauge set and check the charge.

If you have the Stillen G3 intakes they will rub through an A/C line on the drivers side. You might want to check that.

I have 90psi on both high and low sides with the compressor not running, obviously!

It is 80 degrees here today.

The car is bone stock.

The older cars had a amplifier on top of the evap that would go out and cause this problem. Not sure how it is these days. If you are at 90psi, that is not your issue. It is possible that it is the compressor clutch. Ohm out the clutch trigger wire and see what that tells you. Clutch may be bad.

I can get the clutch to engage and compressor run when I put 12v to the wire, so I don't think its clutch.

So I just made a harness to check in between pressure switch and ECM, I am getting 5v into the switch and 1v out, which seems to jive with the chart in the manual for 90psi of pressure. I also pulled the IPDM E/R again and took it all apart, the only relay I could find is the start control relay.
I have an appointment at Nissan to diagnose for $139, but not until the 10th. I'm at a loss.