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Can you prove/test an AC expansion valve? Posted by StoicBlue87 [Email]  (#1829) [Profile/Gallery]
(more from StoicBlue87) on Sat, 7 Sep 2024 15:03:13
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I'm trying to resurrect the AC system on my 92 900s.
Everything that's new:
compressor, hoses, condenser, receiver/dryer, expansion valve.
The system holds a vacuum but upon charging, the pressure readings aren't great; 104psi on the low side and around 190 on the high side. My reference chart indicates these numbers should be around 55 on the low and 300 on the high; my low side is too high and my high side is too low.
The system barely sucks in any refrigerant (r134) and seems to settle out with about .3 lbs. drawn in before stopping any further ingestion.
I've been going through charts and guides and it seems that one likely item is my expansion valve; in my case the valve is stuck open and thus not allowing the refrigerant to change from a liquid to a gas around the evaporator area. I see mentions of people having problems with the valve in these archives and it seems to be simply outright replaced. Some people describe blowing/cleaning them out and I've performed the equivalent with no signs of debris or blockage.
But is there a way to prove that a valve is truly bad?
I have a practically-new spare valve for comparison and both allow me to blow through them with minimal effort when they're at room temperature.
I read that if you place the valves in the freezer for a couple of hours, they'll adjust to closed and block any air when doing the blow test. So far, this test isn't producing a blocked effect.
Is this a valid test? Are there any other things I could check? I'm suspicious of my own impression because both of my valves are new.
The only other thing that might have been causing a problem was a slight over-fill in oil; I opened and drained the compressor of about 1.5 fluid oil ounces...I think the correct amount is 5 oz. and I had dumped in a little more than 6. Maybe the oil was causing the charge issue but...I don't consider myself an AC expert in any way.
Opinions welcome; thanks.
->Posting last edited on Sat, 7 Sep 2024 15:50:58.
, Sat, 7 Sep 2024 15:03:13 <-- Viewing This Message, Mon, 9 Sep 2024 14:51:26, Tue, 10 Sep 2024 06:28:45, Tue, 10 Sep 2024 17:04:42, Fri, 13 Sep 2024 16:10:07, Fri, 13 Sep 2024 18:12:04, Fri, 13 Sep 2024 21:39:30
, Sat, 21 Sep 2024 05:48:23, Fri, 13 Sep 2024 21:53:39
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