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Sir, I purchased a 2001 Chevy Venture WB edition equipped with rear HVAC controls. Whenever the AC is on and the selecor switch for the blower for the rear AC is turned to any of the three (3) positions, I can feel the AC lines vibrate under the floorboard. I have crawled under the van to see these lines actually vibrate. I have taken the van to the dealer 3 times for this problem (A GM Dealer) where I purchased it. They have seen, heard, and felt the lines vibration and have tightened the lines, adjusted the clamps, and put "insulation" (I don't know what type they are referring to) between the clamps and the lines to try to help stop the vibration. The vibration is intermitent and random, but it seems to be happening more frequently and for longer periods of time. The service dept. says they don't know what else to do; they have told me that it happens because of the pressure in the lines...well it did'nt come from the factory that way I'm sure, so its an abnormal problem and should not be occurring. Incidentally, the AC works fine, blows out air fine and gets cold, it's just the vibration and its extremly irritating and loud. I would suspect the dealers mechanics know what they are doing seeing that they sell and service Chevy, Cadillac, Olds and Pontiac GM products as well as Volvo, Nissan, Mercedes-Benz, and Mazda vehicles and should be familiar with them; or so I thought! Please help!
Answer -
Hi Tony, I haven't seen this before but I think I know how to fix it. The pressure in the rear lines is controlled by a expansion valve located at the rear evaporator. I would have them replace this expansion valve and I'll bet that your noise is gone. It must be opening and closing very fast and this will make the pressure in the lines fluctuate causing the lines to vibrate.
Let me know how you make out
Have a Nice Day Mark
Mark,
I just want to say thank you for your invaluable and remarkable knowledge. You were correct in saying it was the expansion valve. I had a long conversation with the service manager, the mechanic, and the service director and they were so stunned, that they called GM technical services (something like that...ring a bell) to verify that that is what it might be. This was the third time it was in the shop and they finally fixed the problem, thanks to you. My hat is off to you sir! Thank you again!
AnswerThank you very much Tony, I answer a lot of questions on this web site and getting a Thank you note is GREAT. It is the only thing I get and doesn't come nearly enough. The auto service is loosing good techs and there aren't any coming in. The young guys just don't have it! They want to make a fast buck even if the cars go out not repaired correctly. This gives techs like me a BAD name. I have no idea what is going to happen in the future when all(the few that are left) good techs are gone. Thank you again
Have a Great Day Mark
