AC Compressor replacement

[jiannichan]

So, it looks like the AC compressor is dead. A mechanic friend helped me troubleshoot the issue to determine that. I understand that I will need to have the refrigerant recovered so I will be taking that to a shop to get done. Has anyone ever replaced the compressor themselves on a 2000 3.3L QX4? How lengthy or difficult will it be to do myself? I found a few sellers with them on eBay. Summer weather is approaching so I'd like the luxury of AC during my drives. Fortunately, I work night shift so it isn't too bad but there will be times I need to stay late where the DFW heat is unbearable. Thanks for the help in advanced!

[Blindaviator]

First thing you need to do is determine exactly how it failed. If the impellers inside fragmented then you have metal particles through out the system & if you throw a new compressor on there it will implode in no time.

Most modern A/C systems have an Orifice tube and some have filters. The orifice tube can act as a filter. You will need to remove one or both (not sure which these systems have) and look for metal particles trapped by them.
Take a look here for more info:
http://www.autoacsystems.com/fasttrack/ ... tube1.html

[jiannichan]

Everything on my ac lines are fine. The compressor just doesn't come on with power applied to it, so it is dead. I've had the system already completely checked out. The compressor just one day decided to not come on after 6 months of not being used, even when it was used during the summer every day before that and worked fine.

[Blindaviator]

Everything on my ac lines are fine. The compressor just doesn't come on with power applied to it, so it is dead. I've had the system already completely checked out. The compressor just one day decided to not come on after 6 months of not being used, even when it was used during the summer every day before that and worked fine.

Ok so the clutch stopped working then?? You tried jumping power directly from the battery to test the compressor??
I assume it still holds pressure in the system??
If so you are in luck then... When you put R134 back in it make sure it has sufficient oil (don't overfill)...

[BubbaFL]

Fairly straightforward job on these trucks. The compressor is easy to access from underneath.

Be sure to replace the recevier/dryer and expansion valve. and any o-rings you can while you have things apart.

You'll need a vacuum pump and set of gauges to make sure it holds vacuum before recharging it. If you haven't done A/C work before, it'd be worth finding a friend who can walk you through this.

[jiannichan]

Everything on my ac lines are fine. The compressor just doesn't come on with power applied to it, so it is dead. I've had the system already completely checked out. The compressor just one day decided to not come on after 6 months of not being used, even when it was used during the summer every day before that and worked fine.

Ok so the clutch stopped working then?? You tried jumping power directly from the battery to test the compressor??
I assume it still holds pressure in the system??
If so you are in luck then... When you put R134 back in it make sure it has sufficient oil (don't overfill)...

Yes. It was tested like that and I verified with a meter that 2 pin connector was getting voltage when the AC was turned on. In another thread I created, I stated that I had the vehicle at a shop, and who knows what they were testing to incorrectly diagnose the issue (ECU is bad, ground is bad & climate control module failed). But I did watch them check for leaks and they vacuumed the lines and refilled it and found that everything with that was good. I just need to find a reputable place that won't try and rip me off to recover the refrigerant.

Fairly straightforward job on these trucks. The compressor is easy to access from underneath.

Be sure to replace the recevier/dryer and expansion valve. and any o-rings you can while you have things apart.

You'll need a vacuum pump and set of gauges to make sure it holds vacuum before recharging it. If you haven't done A/C work before, it'd be worth finding a friend who can walk you through this.

Glad to know that it is easy to get to. That was my main concern, having room to get to the compressor to remove it without taking a whole bunch of things out. I'll be ordering the parts soon to tackle this. Hopefully I can get it all done in a day.

[nickelghandi]

It is a pretty easy job on Pathfinders and Nissans in general in my experience (two Pathfinders and a Maxima), but are you sure that is really what you need?

Shops frequently overfill with refrigerant by accident (or on purpose) and then when the compressor still doesn't kick on, they recommend a new compressor. The easiest way to check is to start the car, start the AC, and then watch the compressor. If it clicks and acts like it wants to start, but doesn't, then it is good, but you either have too much or too little refrigerant. If it doesn't even try to start, then it could be bad or the shaft could be locked up from being unused for 6 months or more. Usually compressors don't just totally die from not being used for a while.

Why not just stick a screwdriver into the low pressure side and let it vent out? I am not recommending that officially, but it wouldn't hurt much. I am in KY where no one really cares about the environment so I could get away with it without someone complaining, but I still took mine to a shop to have it drained.

R134a is tetrafluoroethane which is technically a greenhouse gas and technically toxic, but the degrees of each are minimal. They actually use it as a vehicle in inhalers to push the medication into your lungs and in "canned air" computer cleaner. It is generally safe to work with unless you catch it on fire.

I almost always run the compressor when using the HVAC at all because the refrigerant actually acts as lubricant for the shaft. That is also why even a perfect AC system leaks over time. Some refrigerant will always slip out where the shaft exits the unit and over 5-10 years it can slip below the minimum pressure for the system to run.

I would do a little more self-diagnosis before replacing the compressor, but that is just me. At your mileage it could easily be the compressor itself and everything I have said could be useless.

[Blindaviator]

It is a pretty easy job on Pathfinders and Nissans in general in my experience (two Pathfinders and a Maxima), but are you sure that is really what you need

He said earlier that they tried direct power from the battery to the clutch and got nothing. Even if it was overfilled with 134 the clutch would still engage in that scenario.

If the compressor was seized then manually engaging it that way would cause it to make a lot of noise & possibly damage the belt as it slid around the locked up pulley trying to turn it.

With the engine off you could easily test the clutch the same way with direct power. Apply the power and listen for the clutch to engage. You can also test for a seized compressor by grabbing the clutch on the front end of the compressor (without the engine running of course) and turn it by hand. It should be stiff but turn under moderate pressure by hand.