Should I drain the oil from my new AC compressor?

[Gareth Randall]

Slightly rambling story, please stay with it, I’ll keep it as brief as I can…

I am about to install a new AC compressor. It came *without* PAG oil, but it has been pre-treated with something called ICE32, which is some sort of assembly lube/additive. The installation instructions specifically state that the ICE32 should NOT be drained, you just fill with PAG oil as normal.

So I filled the compressor with oil on Wednesday, swapped over the manifold from my old compressor, and went to install it. That’s when I found that my receiver/dryer and discharge hose wouldn’t fit, because the manifold was wrong. I’ve now sourced a new manifold, and during that time the compressor has spent a few hours with the ports open to the atmosphere.

I’m now ready to install again, so should I drain the PAG and refill it? Obviously that would mean some/all of the ICE32 would come out as well, but is it that big of a deal? Or should I just go with the oil that’s already in there, because when the vacuum gets pulled, any moisture will get boiled away anyway?

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[Mike]

It really depends on if you will be able to properly (pull and hold 30″) vacuum the system. See, PAG oil is severely hygroscopic and sucks moisture out of the air like it’s its job. If you fill a clear container with it and mark the level, it will just go up as takes on moisture from the air. Point being, the PAG oil that’s been left in the open compressor will have more moisture in it than new stuff. Some ICE32 coming out with it is probably not a big deal. If you’ll be able to hold 29-30″ of vacuum on it for 20-30 mins before you charge it with refrigerant, that will take the moisture back out of the oil and the system. This is because at that lack of pressure, water boils at room temperature. This is why vacuuming A/C systems is part of a basic A/C service and major repair alike.

Edit: missed your last line there, sorry if I’m over-explaining the vacuum thing.

[Gareth Randall]

Thanks for the input. On the grounds that the ICE32 is really just an additive, like Slick 50, and isn’t actually necessary to the operation of the compressor, I’m going to drain and refill.

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