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  • DILYSI Dave

    June 20, 2009 11:18 p.m. DILYSI Dave SuperDork

    So, the WRX AC has decided to go caput. Replaced an O-ring and schrader valve on the high side last month and in only a month it leaked back down. AC shop says that high-side pressures are too high and that points to a clogged expansion valve, and is what is causing my blown high side seals.

    The expansion valve is apparently the first part the put in the car before they build the entire damn thing around it. This means stupid amounts of labor to replace it, which either means $$$ or my lying on my back under the dash board. Neither is appealing.

    Now, if I understand correctly, the expansion valve has no moving parts. It's basically just an orifice - right? If that is the case, and it's got crap in the orifice that won't pass, then it seems like back flushing it could clean it out, without having to disassemble the dash.

    I'm tempted to just keep adding 134, but if the high side pressures are really that high, then I don't want to cause other issues. Thus looking for the quick-n-easy on the expansion valve.

    Am I off base here?

  • ignorant

    June 21, 2009 4:21 a.m. ignorant SuperDork

    the expansion valve is just an orifice and about $0.0003 worth of plastic/mesh. I don't know about blowing the tube out, but I know that during any service they always recommend replacing that valve.

    I do know that adding too much R134a can blow the shaft seal in the Compressor. I found that out first hand..

  • curtis73

    June 21, 2009 11:08 a.m. curtis73 Reader

    You can try backflushing, but 9 times out of 10 is corroded or you'll just end up reclogging it.

    Replacing it is easier than you think. Take out the glove box, then the evaporator core is in the box that is held in with two straps. Undo the straps, pull out the evaporator, replace the expansion valve, done.

    Make sure you evacuate the system first :) Also make sure you replace the drier at the same time. Its in front of the driver's side wheel well, partially accessed by pulling back the inner fender well lining.

  • driver109x

    June 21, 2009 10:52 p.m. driver109x Reader

    Back flush with air first to see if it's clogged then with a/c flush?

  • DILYSI Dave

    June 21, 2009 11:43 p.m. DILYSI Dave SuperDork

    driver109x wrote:

    Back flush with air first to see if it's clogged then with a/c flush?

    That's sorta what I was thinking.

  • shuttlepilot

    June 21, 2009 11:46 p.m. shuttlepilot New Reader

    If it is truly clogged, the low side should be reading some sort of vacuum while the high side spikes.

  • DILYSI Dave

    June 22, 2009 9:10 a.m. DILYSI Dave SuperDork

    shuttlepilot wrote:

    If it is truly clogged, the low side should be reading some sort of vacuum while the high side spikes.

    He didn't give me a low side spec, but said that the high side was over 400 psi, and he implied that that was real high and the cause of me busting high side seals.

  • curtis73

    June 22, 2009 11:50 p.m. curtis73 Reader

    High side pressure spikes are not simply created by restrictions. You'd be surprised how many A/Cs come into our shop after coming from a reputable A/C shop. I'm a relative noob with A/C, but I've fixed many an overcharged system. It makes me wonder when these cars come from a reputable shop and I am able to identify an overcharged system, it makes me wonder.

    Many shops toss in some freon until its cold, or the watch the sight glass until its not frothy anymore, or they charge it on a cold day and expect it to not spike on a hot day. Like many shops they are more concerned about getting the car out the door in operating condition so that it doesn't come back to haunt them. They're not worried about doing it right, they're worried about making it ice cold when you accept delivery of your car.

  • June 27, 2009 8:20 p.m. ehigazy

    I have a 2003 GS 300. Sometimes the A/C will work other times it will not. It is fully charged with refrigerant. Any idea what is wrong. I would greatly appreciate a reply.

 
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