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.

Good troubleshooting!

I data logged my AC pressure sensor and it was also 1.0 volts with the AC on and blowing cold with outside temps at 32C / 86F.

Please update us when you know more.

Will do!

So Nissan dealer wants to replace the compressor for $1700, with no guarantee that will fix the problem!!

In your first post you said:
"I can run 12v to the compressor and clutch will pull and a/c runs."
Did the air get cold?

If it did, I don't think the compressor is bad.

Have the AC pressures been checked?

So the dealer had the car for 2 weeks. They replaced the compressor after they claimed they had power going to the mag clutch, still no clutch engagement.
They took the new compressor off, put original back, recharged system, and I took the car back without paying a dime. Still no a/c.

Nissan Tech Support claims this is not the first time they have come across this in a 370Z.

This shouldn't be this difficult to figure out... it seems like the dealerships are lost unless they have a trouble code.

For example, changing the compressor was throwing parts at the problem. If the old compressor did engage when the clutch had 12v, it makes no sense to replace it with a new one.

If this was my car, I would:
• Verify the compressor ground with an ohm meter.
• Measure the current in the wire going to the compressor clutch using a current clamp. (very easy to do)

If the A/C relay (soldered to the inside of the IPDM/ER) has pitted contacts, you can measure the proper voltage, BUT the contacts may arc and create a high resistance, greatly reducing the current and the clutch can't engage.
- just like when the battery has corroded connections and you try to start the car.

Have you tried the IPDM/ER "Auto Active Test"?
This will verify if the IPDM/ER can control the clutch.

In auto active test mode, the IPDM E/R sends a drive signal to the following systems to check their operation. • Oil pressure warning lamp
• Front wiper (LO, HI)
• Parking lamps
• License plate lamps
• Side maker lamps
• Tail lamps
• Front fog lamps
• Headlamps (LO, HI)
• A/C compressor (magnet clutch)
• Cooling fan (cooling fan control module)

Operation Procedure
1. Close the hood and lift the wiper arms from the windshield. (Prevent windshield damage due to wiper operation)

NOTE: When auto active test is performed with hood opened, sprinkle water on windshield beforehand.

2. Turn the ignition switch OFF.
3. Turn the ignition switch ON, and within 20 seconds, press the front door switch (driver side) 10 times. Then turn the ignition switch OFF.

CAUTION: Close passenger door.
4. Turn the ignition switch ON within 10 seconds. After that the horn sounds once and the auto active test starts.
5. The oil pressure warning lamp starts blinking when the auto active test starts.
6. After a series of the following operations is repeated 3 times, auto active test is completed.

SonicVQ that is all GREAT info!!

You are the first person that I have found that even knows where the A/C relay is. I took the IPDM E/R apart, but saw nothing that looked like an A/C relay.

It is acting exactly like you say, the dealer said he had power to clutch with test light, but not enough current to engage clutch.

I will try the test tomorrow and report back.

Is the best option for the relay to just get another IPDM E/R off eBay or something?

Thanks again for the good info!!

I'm glad you found my post helpful.

I think an IPDM/ER from the scrap yard or ebay would be a cost effective choice.

Here is the link to the Nissan part 284B7-1BN6B:
https://parts.nissanusa.com/p/Nissan...4B7-1BN6B.html

Click on "What this fits" and it shows "Nissan 370Z 2011, 2012, 2013"

To avoid paying the "Z tax" the same part number is also used on:
INFINITI EX35 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017
INFINITI EX37 2013, 2014, 2015, 2016, 2017
INFINITI G25 2011, 2012, 2013
INFINITI G37 2011, 2012, 2013, 2014, 2015
INFINITI G37X 2011, 2012, 2013
INFINITI Q40 2014, 2015
INFINITI Q60 2014, 2015

(from: https://parts.infinitiusa.com/p/8958...4B7-1BN6B.html)

Now you have some options and I suspect the G37 IPDM/ER will be a lower cost, more available and it's the same part. :)

I was thinking the same thing! That is about all that is left to make it not work.

Thanks for the part numbers! I'll report back with results.

So we ran the Auto Active Test today, and guess what?? The a/c relay clicks on/off 3 times after the headlights!!

Makes no sense why clutch won't engage. A/C pressure at 75F is 110 on both high and low side.

Still think a IPDM E/R swap may fix it?

I'm totally at a loss.

Got a IPDM E/R on the way to try out, not getting my hopes up!

So I put the new/used IPDM E/R in and the car would not recognize the key? It had the steering wheel icon come up and would not do anything.

Any ideas?

I did not disconnect the battery and try again for fear the original one would not work again and car would be disabled.

After spending weeks at the Nissan dealer they found a couple broken wires from pressure switch and a bad Auto Amp. A/C blowing cold now!

Reviving this thread to hopefully get some diag help myself.

The A/C Clutch won’t engage when commanded from inside the car.
When using the IPDM test I do hear it toggle on/off.

I think that my problem lies with the outside air temp sensor. It shows an “open circuit” as is indicated by the three blank lines “—-“ on the display. Using a multimeter I determined the sensor is good, and that the return wire doesn’t measure any voltage.

I can’t find where this wire terminates on any of the pinout diagrams, I assume it ends up somewhere in the fuse box or IPDM.

I’m almost certain this is the cause as the a/c stopped working when the damage to the wires happened.

Does anyone know a better way to chase this open circuit down? I’m not the most familiar with electrical work.


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