Automotive Air Conditioning Information Forum

Hey y'all, I will appreciate any advice I can get here. I have a 2007 Nissan Murano. In the process of replacing the alternator a few weeks ago, there was a mistake in which the a/c compressor oil drain plug was loosened and let all the freon out. My boss has a vacuum pump and told me what kind of freon/oil to get and proceeded to vac the system. It wouldn't hold pressure so we knew there was a leak (the ac worked fine before the freon was let loose). So he realized the compressor oil drain plug was loose and when he went to tighten it, it snapped off. He was able to get the other half out with an easy out. Lo and behold he had a compressor laying around in his garage and used the oil drain plug from it. Here's where the problem lies:

The original plug is what I would call a fine thread and the one he used from his compressor is a course thread. He started it, said it wasn't resisting, so he went ahead an put it in. At that point when we went to charge the system, the shrader valve was not working, so he sent the pump home with me to vac and fill the system after I put in a new shrader valve (as a side note, it's amazing how many people work in auto parts stores don't know what a shrader valve is...)

Last night i put the new valve in and vac'd the system, could see it wasn't holding the pressure, gave it a shot of the freon and sure enough it's coming out the oil drain plug. I don't know if it's because the threads are different, if it's not tight enough and now am worried that the threads are messed up on the compressor if I were to even get a plug that matches the original. Any thoughts? Or am I as screwed as I think I am?

Again, any help you can offer, including where I might even find just the drain plug, is greatly appreciated.

kimmiemom wrote: I have a 2007 Nissan Murano. In the process of replacing the alternator a few weeks ago, there was a mistake in which the a/c compressor oil drain plug was loosened and let all the freon out.

Actually, it wasn't freon that was lost in your 2007 but R134a. If a shop did this, they should handle the repair for no charge.

kimmiemom wrote:The original plug is what I would call a fine thread and the one he used from his compressor is a coarse thread.

Huge mistake, a panic mistake. Of course even the originally-correct fine thread drain plug won't thread in now, the coarse plug damaged the compressor threads. I think you're looking at a brand new compressor.

That plug was the high pressure relief valve. It needs to be there, or a high pressure event could shatter the compressor case.

Given that it was overtightened & broken, the pieces dug out - and then replaced with the wrong thread pitch?

It is very likely that the sealing surface and/ or threads are damaged.

I would remove the compressor, remove the wrong valve & carefully inspect the threads & sealing surface. A deep scratch in the surface where the valve seals to the compressor is enough to make it leak.

A new valve may be hard to find. Removing one from a core compressor at the junkyard may be your only choice.

If the threads are badly damaged from screwing in the wrong part, and you can't get the right part to seal up? Yeah, you are buying a new compressor.

A new Denso unit should be under $500

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