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I have a vehicle that is not currently running from which I am pulling the engine. To do so, I need to remove the A/C compressor and condensor, but it is currently charged.

I have borrowed an A/C manifold gauge set and an A/C vacuum pump from AutoZone. I thought I could use this not just to put a vacuum on the system later when I swap to a different vehicle, but to evacuate the R134a refrigerant currently in the system. However, the instructions for the vacuum pump say not to run it on a pressurized system.

So what do I do? I can't take the car to a mechanic to have them properly pull out the refrigerant to a recovery system because the car is not mobile. I know you're not supposed to just dump R134a to atmosphere (though it's not as bad as R12).

Can I run the vacuum pump on the system anyway? Is that effectively the same as dumping it to atmosphere? Where do I go from here?


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up vote 2 down vote accepted

I don't need your end goal here, but in almost every vehicle I have worked on I have never had to remove the A/C compressor with the engine. They are designed to be disconnected from the engine and put to the side so you don't have to discharge the refrigerant from it.

If you absolutely believe you need to remove or discharge the system, take it to a shop which can draw out the r134a from the system in an environmentally safe way. You should be able to work out some kind of deal with them to bring the vehicle back to them for recharge after it's done. Remember, though, you will have to replace the dryer when you put it back together, as well as recharge the r134a.

Using the vacuum pump to remove the r134a will do the same thing as just dumping it directly into the atmosphere. If you cannot move the vehicle and only want to dump it, you really need to be careful of the r134a freeze burning you as it decompressed out of the system. Obviously, I don't recommend this approach if at all possible.

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