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A/C Expansion Valve Failure? Posted by Gene N [Email]  (#1094)  [Profile/Gallery]
(more from Gene N) on Mon, 5 Aug 2002 12:52:18
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Has anyone had a replaced expansion valve fail after a month and half?
Here is the situation on my 1991 9000T. I replaced the condenser (corrosion and a lot of rock dammage on the bottom tubes), the compressor hose (the hoses turned on the fittings and showed some sign of leaks), the compressor (weak and was the original, also showed some signs of seal leakage), the receiver-dryer, and the expansion valve. I flushed the remaining parts (one hose and the evaporator) with HC-141b, a standard A/C flush. New oil (5 oz.) and 38 oz. of R-12 (charged by weight). I fired the system up and it cooled great. 48 degree air at the vent and pressures around 26-28 psi on the low end and around 220-240 on the high end. The system continued to work very well for a month and a half in 90 to 100 degree weather. Last week, one day, it worked fine in the morning, and then I got almost nothing at lunch time.
Checked the pressures the next day after things had settled overnight and the low side was 10 psi and the high side was 200. The air was about 5 degrees cooler out of the evaporator and the expansion valve was slightly cool. The sight glass was clear--no bubbles. I added 4 oz. of freon and the intake pressure went up to 15 psi and discharge pressure started climbing to over 300 psi, so I could see that the system was probably not low on freon. I pulled about 8 oz. of freon out the system to see if the system was overcharged, and the high pressure went down, but still no cooling. The sight glass remained clear.
The reason I suspect the expansion valve is the problem is that sight glass is clear. If the receiver dryer was clogged, I would expect bubbles in the sight glass, because the 10 psi suction pressure would boil the freon downstream of the receiver dryer, and probably frost the lines.
How's my reasoning sound? If it's correct, why would the expansion valve fail so quickly?
posted by 140.188.64...
, Mon, 5 Aug 2002 12:52:18 <-- Viewing This Message, Mon, 5 Aug 2002 14:39:06, Mon, 5 Aug 2002 15:20:47, Mon, 5 Aug 2002 14:45:53, Tue, 6 Aug 2002 14:10:58
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