AC compressor problems? Can turn by hand but...

[Serdriver]

Hello,

New to the forum, but not new to fixing my own problems. I’ve been reading through the stickies and found lots of great info (how to fix my broken clock, the PÍA to replace the stock head unit, etc) so thanks in advance.

I just picked up a 2001 Pathfinder LE with non working ac and have a few questions.

Blows warm air really well, all fan settings work, and the heater works great, and I san move the air to different vents. so I checked the low pressure side to see if I needed coolant and it was HiGh, red zone high. So I released some pressure and a bunch of yellow/green dye came out. Got it back to the blue green zone so it’s not over pressurized. I can’t hear the compresor clicking, but (with the engine off) I can turn the clutch by hand but it doesn’t spin on it’s own (does this mean it’s NOT seized, right, because I can spin it by hand?)

This makes me think the ac lines are clogged but maybe the compressor is actually still Functioning? I think it’s clogged because the former owner tried to see if there was a leak with the ac dye but it didn’t really go anywhere, just stayed in the low pressure line.

I think I I have 3 options (and this is were I could use some advice).

1) vacuum out the ac lines to see if any moisture/air gets out and then refill the ac system to see if it works. This would be minimum cost because two cans of ac recharge cost about $30 and I can rent the vacuum from oreilly. I’ve never used one before , but doesn’t seem to difficult.

2) replace my compressor, along with drier for about $200. (And yes, Im changing my belts too!)

3). Replace the compressor, condenser and drier and expansion valve for $300. All these parts would come from Rockauto. I’ve done this before on a Subaru, so I’m familiar with the process and I wouldnt have to guess if anything works or doesn’t work.

Anything else I’m missing. Reading over this it seems the vacuum part is easiest and most cost effective, so I will probably try that first.

Any thoughts? Thank you in advance.

[laszlo1]

Your model has a V6 variable displacement compressor. That means that its displacement is governed by the high side and the low side pressure, as well as the RPM. The FSM (Factory Service Manual), downloadable on this site under tab "Service Manuals" above, has a lot of information about the a/c, including on how to run the automated self-test. The section on the a/c and heating in the manual is called "HA".

Because of the complexity, you probably want to do more diagnostics before replacing any parts or opening up the system.

[mdmellott]

I agree with laszlo1. Check the obvious first. (fuse and relay) A/C high pressure cut-off switch may have gone bad if it has been over pressurized for a long time and sitting idle. Like laszlo1 said, A/C systems can be complicated to troubleshoot for the DIY driver. Best of luck to you.

[Serdriver]

OK, thanks for the replies.

I looked at the FSM and looks like I will need the AC gauges to properly test the system because the self diagnosis doesn't check the cause of insufficient cooling, but good to know nonetheless. Once I have the time to test I will update here.

[Serdriver]

Also, after looking through the diagnostic check for insufficient cooling, I'm left with two choices: either bad blower motor or bad compressor. My blower is working fine from what I can tell because it can vary the speed and I can change the direction of the airflow, so I'm guessing it's the compressor. Also, I've been reading the longevity thread (post your mileage and year of your Pathfinder!) and I've seen many people who've had to replace the compressor, so I'm guessing that's it. But again, I will go through the testing procedures to make sure.

If I do need a new compressor, I'll go back to my original question: should I replace all components (compressor, condenser, expansion valve, o rings), or just the compressor?

Thanks!

[mdmellott]

Never had to replace a compressor on either one of my Pathfinders but did so on an old Ford I once had. Only replaced the compressor. Nothing else was broke so there was no need to replace other parts. Having a service tech with the right tools to recharge the empty system is highly advised so they can draw a vacuum on the closed system to purge all the old PAG oil for one and assure there is the correct negative pressure in the system before fresh oil and R134 are added back. I skipped the service tech on my old Ford and never did get the A/C as cold as it should have been. I had to dismantle my old '91 Pathfinder's A/C system and put it back together with the same parts when I rebuilt part of my engine. Had the system recharged by a service shop. The A/C put old the chill better after that recharge than it had ran before I took it apart.

[Serdriver]

I think I fixed it!

I completed the self diagnose, everything was working as it should. Then I got a loaner AC gauge set from O’Reilly and tested the the low and high pressure with the car off and then running. The low and high sides had equal pressure while the car was off and while running, so yes, the compressor wasn’t running.

Next I evacuated the remaining pressure and listened to previous advice in this thread and replaced the pressure switch ($13 on Amazon), refilled with refrigerant and Viola! the compressor came on and I have cold air! I drove it around for about half an hour and it stayed cold. I’m going to recheck the pressure today and hopefully it’s still good, meaning it’s not Overpressurized.

I think the previous owner overpressurized the system by putting in too much refrigerant, causing the pressure switch to fail after the car sat for months.

Thanks for the advice.

[rgk]

How did the loaner vacuum and gauge set treat you? Did you refill the oil in the compressor?

[Trinikilla]

Any part numbers for the pressure switch

[mdmellott]

Any part numbers for the pressure switch

You have listed in your profile a 2001 Infinity QX4 so I assume you're asking about the A/C pressure switch for that. If you have the '01 QX4 model with a 3.3L engine, the pressure switch part number is 92137-0W000. If you have the 3.5L engine, the part number is 92136-3Z600.