Is my expansion valve bad?
10-24-2005, 11:46 PM
#1
Three Wheelin'
Thread Starter
Is my expansion valve bad?
Overnight, my AC no longer blows cold--it's a little cooler then fresh air, but not much. I have determined that it's not a vacuum leak allowing the heater valve to open.
I found 12V on both sides of the freeze switch, but jumpered it anyway.
My compressor engages, because the expansion valve gets cold to the touch...
I heard some hissing behind the dash when I turned on the AC...which I assumed was the expansion valve. I think hissing is also symptomatic of a low charge, but my pressure, even at these lower fall SoCal temperatures is enough to still engage the compressor.
I figure that maybe my expansion valve has becomed clogged...
Anyway, next spring I'll probably have all the lines, o-rings, drier, and expansion valve replaced, but wanted to see if anyone had thoughts about what my problem could be and why it would've appeared overnight...
Would it make any sense to have the system vacuumed and just the expansion valve replaced, or if I'm going to have it evacuated, should I just plan on doing all the items of unknown age as insurance against the "fix one only to have something else fail in 6 months" syndrome?
I found 12V on both sides of the freeze switch, but jumpered it anyway.
My compressor engages, because the expansion valve gets cold to the touch...
I heard some hissing behind the dash when I turned on the AC...which I assumed was the expansion valve. I think hissing is also symptomatic of a low charge, but my pressure, even at these lower fall SoCal temperatures is enough to still engage the compressor.
I figure that maybe my expansion valve has becomed clogged...
Anyway, next spring I'll probably have all the lines, o-rings, drier, and expansion valve replaced, but wanted to see if anyone had thoughts about what my problem could be and why it would've appeared overnight...
Would it make any sense to have the system vacuumed and just the expansion valve replaced, or if I'm going to have it evacuated, should I just plan on doing all the items of unknown age as insurance against the "fix one only to have something else fail in 6 months" syndrome?
10-25-2005, 12:05 AM
#4
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
If the expansion valve plugs, you'll be able to see that instantly with a gauge set. The high side pressure will be too high and the suction side quite low. Easy diagnosis.
More likely is that the leaks have finally allowed enough freon to escape that you no longer have liquid flowing to the expansion valve. If your drier has a sight glass, take a peek and see if you see the gas change to liquid when you first turn the system on. Normal operation has the system as gas, high side goes to liquid when the compressor runs and the condenser is condensing. Again, the quick diagnosis is with a set of gauges.
Reality is that expansion valves seldom if ever go bad on their own. Dirt/crud/rust/moisture will kill them, but in a clean system they last forever.
More likely is that the leaks have finally allowed enough freon to escape that you no longer have liquid flowing to the expansion valve. If your drier has a sight glass, take a peek and see if you see the gas change to liquid when you first turn the system on. Normal operation has the system as gas, high side goes to liquid when the compressor runs and the condenser is condensing. Again, the quick diagnosis is with a set of gauges.
Reality is that expansion valves seldom if ever go bad on their own. Dirt/crud/rust/moisture will kill them, but in a clean system they last forever.
