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Followup To
Question -
The A/C in my car went bad recently. I tested the pressure at the low side port to be very high when the engine is off. However, the pressure becomes negetive after the engine runs for a while. Then I turn off the engine, the low side reading resumes slowly to the previous value. Of course, this system won't produce cool air. I guess the problem comes from the blockage of the expansion valve or the failure of the remote sensing bulb but I am not sure. I guess so because several days before the failure of my AC, I heard a loud metallic sound from the compressor area; the noise disappeared after several minutes; several days later, I found the AC can only operate for a short time and then no cool air came out. So, maybe debris from the compressor blocked the expansion valve? Can you provide advices on my problem? Thank you.
The car is a demestic 1995 toyota corrola
Answer -
Your observation is correct. What has most likely happened is that the compressor is damaged internally and has either partially plugged the REED VALVE(S) and thus has the expansion tube restricted with debris from the compressor.
Naturally when the engine is OFF the LOW and HIGH side pressures will EQUALIZE and read almost identical pressure of the LOW and HIGH side, This IS normal.
autohelp
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Dear Sir,
I appreciate your answer very much. Your answer gives me the following questions:
1.What is the "REED VALVE", is that a part of the expansion valve?
2.You said my compressor is damaged, does that mean it has to be replaced? I noticed that it can still produce cool air for a while before the system is blocked by the expansion valve.
I plan to replace the expansion valve, the receiver and drier, flush the system, evacuate the system and then recharge it. Is it possible to fix the problem without changing the compressor? You know I am a poor graduate student :)
AnswerYou CAN go ahead and JUST relace the expansion valve (orfice tube), Flush the system, Replace the receiver/drier, Evacuate and recharge, BUT WHAT plugged up the expansion tube (orfice tube) ?.
Upon removal of the orfice tube if you find fine pieces of metal and or aluminum, This would most likely be from the compressor.
The REED VALVES are inside the compressor.
Go ahead and try it, You can't hurt anything. You might get LUCKY and only have to replace the expansion valve (orfice tube) a couple of times until all of the debris stops re-clogging it.
autohelp
