awilli6

Hey gang,

Just finished the compressor, drier & expansion valve install on my 87 S4. Added the oil to the compressor while it was on the ground. Do I have to get someone to pull a vacuum on it and then add freon, or can I just add freon?

If I need vacuum pulled, I'll have to take it to someone.

Ducman82

Yes, you need a vacuum pulled or else a lot of moisture will eat all the new parts.

Mrmerlin

you will want to get a vacuum pulled ,
then let the system sit for a few hours or overnight to check for leaks.

Using the vacuum pump thats made for A/C system work is the best choice,
as the longer the pump is left pulling a vacuum the more moisture will be removed from the system.
SO its best to leave the pump running for a few hours.

awilli6

Thanks guys. I'll get set up with a local shop

Imo000

If you already hooked up the drier to your car then might as well go get a new one. Open to the atmosphere a drier will be ruinned in 8hrs.

FredR

The system is designed to fully condense the refrigerant- it cannot do this if there is air in the system as this is non condensible.

The drier is designed to absorb any moisture in the residual air and then some. If you installed the drier and boxed up the system immediately I doubt very much that the drier will be damaged but fully agree that the sooner the system is sealed and evacuated the better. For sure you do not want to leave these things open to free air ingress for too long. If you have any doubts ask an air conditioning specialist for their input.

The system should be evacuated to at least 29 inches Hg [the deeper the better] and must be able to hold that vacuum. The amount of time you need the vacuum pump is largely dependent on the efficiency of the vac pump itself to get to the desired value but I always ask the a/c tech to leave the system for at least one hour before filling with gas to test for any leakage.

Rgds

Fred

awilli6

Took the car to get vacuum pulled and freon added and was told I have a high side restriction. What do I need to do to identify where the restriction is. Could one of the lines I had off to install compressor, drier and expansion valve be restricted in some way?

SeanR

If there was any debris in the lines it would get caught on the small line leading to the expansion valve. This is usually where the drier desiccant goes when allowed to roam free.

awilli6

Thanks Sean. So if I remove the small line there may be debris that can be removed or do I need to blow it out some way? Where would that line originate to put compressed air behind it?

SeanR

That line goes all the way forward to the small/passenger side, connection on the drier. If you have debris at the expansion valve then I'd pull the valve and drier and clean that line real well. Compressed air and lots of brake cleaner until it's free of whatever is in there. I'd also put a new drier on there if this is the case.

One of the first indications that there is an issue on an A/C system is if the old TXV you pull out is cruddy or has a blockage, then it's a good idea to flush it.

awilli6

Thanks. I just put this drier on. Calling Roger...Again