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Intermittent compressor function - how to test/rule out clutch

James89dx on Fri March 13, 2015 4:41 PM User is offline

Year: 1992
Make: Nissan
Model: Maxima
Refrigerant Type: R134

This may be uselessly long but I want to provide the full back story:

I have two 3rd gen Maximas. A 1992 and a 1993. The 92 was factory R12 and the 93 was factory R134. The 92 had a big leak somewhere and rather than throw R12 at it and mess with it I just decided I wanted reliable good air in it. Thankfully since the R134 crossover happened in the middle of the model run I could just get a true R134 system from a 1993 or 1994 Maxima.

So I went to the JY on 1/2 price day and pulled a complete good R134 system from a 1994 Maxima. Interestingly, all the hard parts (evap, condenser, etc) all appear to be totally identical between the R12 and R134 models even though the 134 stuff is all labeled "R134 only".

My swap did include me wiring in the R134 system's thermo control amp and bypassing the R12 outside ambient temp sensor. The two systems also had different pressure switches and I wired in the R134-specific switch. All went well, and I had perfect ice cold air in the 92 Maxima at this point. Cycled normally, got ice cold, perfect.

As I drove it more and more over the past year it would intermittently and randomly develop a condition in which the compressor would not engage. It will work perfectly for days/weeks then out of the blue not work for 5 or 10 minutes, or a day, or two totally intermittently. It would be as sporadic as to not work at all on my lunch hour drive to a restaurant, then work flawlessly on the drive back. I swapped around relays, swapped in a complete different climate control unit, all sorts of stuff.

When the AC won't work it's because the compressor will not kick on. My ideal scenario would be able to test at the compressor during one of its "outages" to see if it's getting 12V at the time it's acting up, but I cannot ever get it to not work when I'm in the driveway with all my tools. It always happens when I'm out driving it unable to test.

I'm leaning toward the clutch as the culprit. If I ever am lucky enough to repeat the no-AC problem in my driveway - and during this time I disconnect the AC harness at the compressor and do have 12V at that connector, does that definitively mean the clutch is the culprit? How could I rule the clutch in or out if I'm not able to repeat the no-AC condition in the driveway?

Dougflas on Fri March 13, 2015 5:06 PM User is offline

You could wire in a small 12v lamps with a long set of leads and place it inside the vehicle. When the problem occurred, see if the lamp is lit while it is wired at the clutch. KISS

James89dx on Fri March 13, 2015 5:28 PM User is offline

Interesting. I could hook this up to a little 12V LED or something.

Just so I understand, are you saying wire the lead in-line on the actual compressor wire? It is just a single wire like this:



In that case, does the compressor see a constant 12V anytime the AC button on the dash is enabled? Meaning if so, that anytime the LED would not be lit that I know the clutch is the culprit?

OR does the 12V source to the compressor get interrupted from other entities like the pressure switch etc




Edited: Fri March 13, 2015 at 5:29 PM by James89dx

Jag987 on Sat March 14, 2015 3:08 AM User is offline

Quote
Originally posted by: Dougflas
You could wire in a small 12v lamps with a long set of leads and place it inside the vehicle. When the problem occurred, see if the lamp is lit while it is wired at the clutch. KISS

That is just what I was thinking.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

GM Tech on Sat March 14, 2015 11:42 AM User is offline

Sounds like a wide air gap- next time it is off- pull over and tap on front of clutch plate- see if it kicks on- be careful of moving parts- use a long probe- like a hammer handle

Clutch voltage is switched on and off by switches and sensors- not only by a/c request from control head.

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Cussboy on Tue March 17, 2015 1:24 AM User is offline

Quote
Originally posted by: Dougflas
You could wire in a small 12v lamps with a long set of leads and place it inside the vehicle. When the problem occurred, see if the lamp is lit while it is wired at the clutch. KISS

I have such wire soldered-in to my AC clutch wire on my truck. It feeds a blue dash light when the compressor gets voltage. It helped me diagnose a clutch slippage issue a few years ago.

James89dx on Tue March 17, 2015 12:10 PM User is offline

Quote
Originally posted by: GM Tech
Sounds like a wide air gap- next time it is off- pull over and tap on front of clutch plate- see if it kicks on- be careful of moving parts- use a long probe- like a hammer handle



Clutch voltage is switched on and off by switches and sensors- not only by a/c request from control head.

I will try that, thanks. I have read on some Subaru forums that they have a common issue with the gap being too wide and causing the compressors to suddenly stop working. A common fix for those guys is to simply remove one of the shims. I wonder if ultimately I could just do something like that.


Quote
Originally posted by: Cussboy
Quote
Originally posted by: Dougflas
You could wire in a small 12v lamps with a long set of leads and place it inside the vehicle. When the problem occurred, see if the lamp is lit while it is wired at the clutch. KISS



I have such wire soldered-in to my AC clutch wire on my truck. It feeds a blue dash light when the compressor gets voltage. It helped me diagnose a clutch slippage issue a few years ago.

How do you have it wired? Is it just simply teed in to the compressor power wire?

Cussboy on Tue March 17, 2015 2:46 PM User is offline

Quote
Originally posted by: James89dx
Quote
Originally posted by: Cusser


I have such wire soldered-in to my AC clutch wire on my truck. It feeds a blue dash light when the compressor gets voltage. It helped me diagnose a clutch slippage issue a few years ago.

How do you have it wired? Is it just simply teed in to the compressor power wire?

I have a single wire on mine that goes to the AC compressor clutch. Just before the conenctor to the compressor, I stripped back some insulation on the wire and wrapped a new wire around that, and soldered it, and wrapped with electrical tape; I feel that's way stronger than cutting the wire and using a crimp-connect. That wire feeds through and under the dash to the $5 panel light assembly, from Autozone or O'Reilly, in several colors, so I chose blue. That light has two feeds, one for positive and the other to ground. So every time the AC clutch gets power, the light also comes on. I guess being in the Arizona desert, it's comforting to see the little blue light on !!!


Edited: Tue March 17, 2015 at 2:46 PM by Cussboy

James89dx on Wed March 25, 2015 12:59 PM User is offline

Very cool. I will have to try this out. Thanks

James89dx on Sun April 19, 2015 11:18 AM User is offline

Okay, so I wired up an LED just as described above and have been driving around waiting for the AC to not work so I can test it.

Yesterday it finally happened - compressor would not engage and my LED was NOT lit up at the time, which means my whole problem here isn't the clutch. I was really hoping that would be the problem :/

Where shall I go from here?

wptski on Mon April 20, 2015 8:08 AM User is offline

Back track the circuit using your LED.

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