AC purge

[Bri-Guy-GA]

I replaced my AC compressor and the drier and now need to get the system purged and charged. Should I install the oil in both parts or will it go in when they charge the system?

[J]

how hard was it to replace your compressor? It looks pretty strait forward. I would think it would go throughout when they charge it, but it wouldn't hurt to put a lil in both

[Bri-Guy-GA]

It came out pretty easy. The drier was a bit harder due to the air box and all being in the way, but once it was out, it was just a matter of having big wrenches. Took less than an hour.

[kuwaitliberation]

Depends on if you want to go back with R-12 (if that is what you had before) or retrofit to R-134a.

 

My suggestion would be, no matter what, to go ahead and use soap and water in all pipes to wash out any remnants of anything. Use 3 in 1 oil and slightly lube the o-rings to carefully fit the entire system back together. You must then take a vacuum on the system to purge any water that is in there (after washing it, there will be). You can't have one drop of water.

 

When you take the vacuum, it (of course) lowers the pressure in the system. This brings the boiling point of the water way down to below room temperature. The water will flash-boil and be drawn out through the vacuum hose. Hold a vacuum on there for about an hour (you really only need about 10 minutes, but better to be safe than sorry). After that, hook up your fill lines and start the car. Turn on the A/C to kick the compressor on. Then open the fill valve.

 

You can actually get the R-134a that has everything in it that you need. I mentioned it in another thread, but you go to walmart and they have this stuff that has R-134a coolant, an agent that adds 10 degrees more cooling, 1 oz of oil charge, stop leak and o-ring conditioner. You will need 3 to 4 cans of that stuff.

[shyguy164]

Just to clarify a bit, you've got to start charging before attempting to run the compressor. The compressor has a low-pressure cut-off switch to prevent damage to it. I'd also suggest using gauges with the vacuum pump. Not only should you run the pump for a half-hour or so, but make sure the system will hold the vacuum for at least an hour. If it doesn't, you've got a leak. There should've been instructions with the new compressor telling you how much oil it requires. It might also require a special oil fill procedure. Check your service manual too. I would not rely on a can of stuff from wal-mart to supply the compressor with enough oil. Replacing the system is one thing, properly charging it so that it doesn't break in an hour is another thing. If you've never done this before, I'd recommend going to an A/C shop to have them vac and charge the system. Afterall, there is a reason the EPA requires certification for working on A/C. I've got that certification, let me know if you've got any questions.

[Bri-Guy-GA]

I was planning on going to a shop since I don't have the equipment to purge the system and test it properly. When I took it apart I broke the connections and cleaned the fittings and O-rings. The instructions did say how much oil to put in the compressor and drier. I just forgot to do it at the time. Guess this weekend I will put some in and get it purged next week. Let you know how it goes.

[kuwaitliberation]

Just to clarify a bit, you've got to start charging before attempting to run the compressor. The compressor has a low-pressure cut-off switch to prevent damage to it. I'd also suggest using gauges with the vacuum pump. Not only should you run the pump for a half-hour or so, but make sure the system will hold the vacuum for at least an hour. If it doesn't, you've got a leak. There should've been instructions with the new compressor telling you how much oil it requires. It might also require a special oil fill procedure. Check your service manual too. I would not rely on a can of stuff from wal-mart to supply the compressor with enough oil. Replacing the system is one thing, properly charging it so that it doesn't break in an hour is another thing. If you've never done this before, I'd recommend going to an A/C shop to have them vac and charge the system. Afterall, there is a reason the EPA requires certification for working on A/C. I've got that certification, let me know if you've got any questions.

Agree, totally! I worked on A/C systems, but under commercial applications. I did swap the entire system out in my Olds 98 and upgraded to R-134a and I did use the walmart stuff. It was good for 2 years and I got rid of it with working A/C (there is the reason I got me a W-Body). Might have been luck or whatever, but I do have a vacuum pump and all, so it wasn't a big deal. I also tested the vacuum overnight and it didn't drop one bit. Like I said, may have been luck, but I have worked on A/C systems before. I would definatly listen to shyguy, seriously. I am all about taking the risks because I am one to not let anyone else touch my car. I might just sell it if it gets to the point I would have to take it into the shop.