Fixing my AC and retrofitting to R134A, do I have this right?

[Ryanb56]

I have a 92 explorer that appears to have not yet been retrofitted yet. The AC didn't work when I bought it and has no charge in it. After a reading through on here I think I have a plan. First is to flush the system after removing the compressor. I haven't found a lot of detail about this but it sounds like you can spray a bunch of brake cleaner in the condenser and evaporator, then blow it out with compressed air and this will remove the residual oil, is that correct? Then I figured on replacing the compressor, o-rings, orifice tube, and drier since I have found these as a kit for $200. Then I hook up a manifold gauge kit and vacuum pump and evacuate the system, leave it on for 30 min or so to remove the air and residual moisture in the system. If once I disconnect the vacuum pump and it holds vacuum for a couple hours after that, hopefully there is no leak correct? Then I can follow the specifications for recharge with R134A. Do I have this process correct? Also, about vacuum pumps, the Robinair ones look like they are about $200 but there are some other brand ones on ebay for around $100. Anyone have any advice on this? I want to get one that will do the job correctly but I don't want to spend too much considering I only plan on having to use it a handful of times ever. Thanks to anyone who has done this before or you AC guys that can set me straight on this. I really appreciate it.

 

[Earl43P]

Should be able to do the leak check with the vaccum pump and gages still hooked up. Other than that, your plan sounds solid. We used to flush with isopropyl alcohol when we converted R-12 systems to R-134a (aircraft). Cheap stuff compared to how much brake cleaner you'd need. One gallon ought to do it.

Disassembly should reveal how bad it is. If you find a lot of black stuff, figure on replacing the compressor.

The Haynes manual has a very detailed procedure to fine tune its cooling output, using a thermometer in the outlet duct. It's easy to overservice with r-134a.

 

[4x4junkie]

I used lacquer thinner to flush mine out (probably 1-2 quarts worth... mine was pretty clean inside already when I took it apart).

Whatever you use, you don't want it to leave any residue inside the coils (brake cleaner isn't completely residue-free, I've found). Blow it out a few times, waiting 30 min to an hour between each time.



$200 for a compressor and the accumulator sounds awfully cheap... I'd make sure to get a quality (new, not rebuilt) compressor if it's to last awhile. If the hoses are original, I'd probably swap those out for new ones as well.

 

[Ryanb56]

Do you think that $200 is too good to be true? I have seen quite a few places that have compressors for around $150 so I thought this was a good deal but not too good to believe. It says all parts are new. Thanks for the replies guys. I really appreciate it. Also I saw some vacuum pumps on ebay for $100 shipped that I think are the US General brand. They say they pull down to 75 microns, do you see any reason one of these wouldn't work for me? Thanks.
Ryan

 

[4x4junkie]

Unless they've come WAAAYY down in price (not sure), a NEW OEM-quality compressor was a minimum of like $300.
When I redid the A/C on my BII, my research found that Ford FS-series compressors fared particularly bad as rebuilds, so is why I would say don't even bother with rebuilt ones, get an all-new one from a reputable manufacturer (Visteon makes the OEM ones).

US General is a Harbor Freight brand (made in China). Like many products from that place, they'll usually work, but you might need to tinker or modify them somewhat to maximize their performance because of deficiencies in their quality of manufacture. If you're good with doing that kind of stuff, then I'd say go ahead and get it (quality-made vacuum pumps are generally $400 and up).