Expert: Roland Finston - 6/20/2011

Question
QUESTION: Hi, I have a 2000 T&C, 3.3 engine.  I am hearing a hissing sound, something like pressure bleeding off, when the AC is running.  The front AC is cooling properly but the air coming out of the rear AC vents is not cool. Please help me!

ANSWER: It sounds to me like there is a leak of some sort with that hissing sound, but exactly what it is needs to be found by listening carefully and finding the source. Once that is found and sealed see how the system works. I can't offer more than this at a distance.

---------- FOLLOW-UP ----------

QUESTION: I don't believe there is a leak because the pressure reading on the gauges have been the same for a couple of months.  I have been checking the low side since my wife began complaining about the sound. I just hooked up the high side and see that the high side pressure rises and then returns to normal.  This is a continuous cycle.  The pressure bleeding or hissing sound shows up when the high pressure reading is returning to normal from a high state. Could the expansion valve for the rear ac unit be bad?

Answer
Hi Ed,
Certainly if the sound is coming from the rear that would be a good working hypothesis. Also, cancelling the request for rear AC and observing the absence of the hiss would corroborate.
You can access the unit by removing the panelling. Let me know if you want the instructions and I can send you the pages as an attachment to an email. But you need to tell me your email address via a 'private' follow-up question where you list that address in the text.
Roland
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