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Discussion Starter · #1 ·
Hello all...well, my AC isn't working again. Put a new compressor, and dryer on it Feb a yr ago. I do have a leak somewhere but not enough to try and find. At any rate, the AC had gradually lost cooling and I went out of town for a few weeks. When I got back, the AC didn't cool at all Put my gages on it the static pressures we both 50# @ 90 °F. I started the engine and jumped the LPS. The low side went up to about 70# (freon can pressure I assume) but the hi pressure side would never get above about 50#. It would not take the charge. I think the compressor is gone again, but a mechanic friend suggested the expansion valve may be plugged. Any ideas will be appreciated
 

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If the expansion valve was plugged the high side would quickly climb and keep going until the high pressure switch cut it off or something blew. Expansion valve may be stuck open though. Even with a stuck open TXV the high side should be equal to or higher then the low side pressure.
 

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Discussion Starter · #3 ·
Actually, depending on the accuracy of the gage set, the static pressures were: LO side was @ 52# and the HI side @ 45#.
I then set the AC controls on max, and then jumped the LPS. When the compressor came on, the LO side dropped to 40# and the HI side pressure movement was negligible. The compressor did rattle just a touch. Like it was at least trying to pump.
 

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Discussion Starter · #5 ·
Thanks Gizmo...So what I'm getting out of this is that you think the txv could be stuck open...right? So is kinda ruling the compressor out ?
 

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Discussion Starter · #6 ·
I also noticed it took longer than I expected for the HI & Lo sides to equalize after I killed it....over an hour...I guess if the txv is stuck open, the there's not enought pressure drop across the evaporator to change the freon from liq to gas ?
 

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If the TXV is stuck open it will equalize faster. TXV is basically a restriction in the line so the farther open it is the less restriction meaning faster equalizing.

It has me confused now. Pressures suggest TXV stuck open but taking so long to equalize suggest its stuck closed. A restriction somewhere else in the system would act just like a TXV stuck closed, low pressure on the low side and high pressure on the high side.
 
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