DIY Air Conditioning
Now to put everything back together. You want to try and keep dirt off of the o-rings. Even very small pieces of dirt can clog the expansion valve.
The first thing to do is to swap compressors and then remount the new compressor onto the engine.
Now install the new expansion valve. Be sure to use o-rings on the fittings or else freon will leak through this.
Put the cover back on the evaporator and then you can connect the compressor hoses.
Now install the new receiver/drier and connect the hoses to it.
The final step is filling the system with gas. You can do this yourself if you have some special tools. The required tools are the R134 gauges and a vacuum pump.
The gauges can be bought for $50 online or from a car parts store. The vacuum pump is expensive, so try to borrow it.
Hook up the vacuum pump to either side and let it run for at least 10-15 minutes. After this you can do a preliminary check for leaks by closing the system in a vacuum state
and watch the gauges. If you lose your vacuum then you have a leak somewhere!
Filling the system requires knowing about how much freon you need and reading the gauges to determine the pressure in the system. From what I've seen
the low pressure system should be around 30 psi and the high pressure should be around 250 psi.
You also need to add some oil into the system. If you don't your A/C compressor could sieze!
Some new A/C compressors come oiled by the factory and others do not. Just follow the recommendations in the box.
If you are using an old compressor, then you need to add oil for sure as the vacuum pump would have sucked everything out.