[HELP] Unevenly cooled A/C

[GreatFrog]

hi, I just bought a 2005 325i. The A/C works but the wind temperature on the passenger side is a significantly higher than the driver's side. And this is when engine turned on. When the engine is off and the car is in cold condition, both sides give the same temp.

Dealer told me it might has some problem with the evaporator, and may cost over $1k to repair! is it true? I think if one side works, the evaporator should be fine. Since I tested the A/C with engine off today and it turn out to be normal, I seriously doubt that may be there is some problem with the engine heat insulator? The cooled wind on the passenger side picks up the engine heat?

Anyone can help? Thanks in advance!

[darkhorse737]

ummm.. really, that should be the least of your concerns

I do not think there is anything wrong with your system. Heating (or cooling, for that matter) is all done by conduction. It is to say that over a period of time, the temps of your car will all be even over a given period.

If you are looking for a detailed explanation why you experience a difference in heating/cooling for your car, notice the length in the ducting passenger side vis-a-vis driver's side. Driver's side ducting is at least 1.5 times longer due to the positioning of the climate control system. Long ducting takes longer heating/cooling time, and of course blow pressure will decrease, the longer the duct is.

You are correct to say that evaporator does work. If anything, it is well possible that one of the blower doors isn't fully opening or closing.



* while on the subject and you are itching for something to do... when was the cabin air filter last changed? Cabin air filter serves as your air intake to your cabin blower. If restricted, it may also result in reduced blower efficiency.

[GreatFrog]

hi Darkhorse737,

thanks for your reply. It does alleviate my concern about the cooling system. But if the driver-side ducting is 1.5 times longer than the passenger side, shouldn't the driver-side temperature be higher? I am just confused about this. If temp difference is indeed due to the different ducting length, is it to say that the difference in temperature is inherent with the E46 design? I may want to check the blower though, as you suggested.

Thanks!

Originally Posted by darkhorse737

ummm.. really, that should be the least of your concerns

I do not think there is anything wrong with your system. Heating (or cooling, for that matter) is all done by conduction. It is to say that over a period of time, the temps of your car will all be even over a given period.

If you are looking for a detailed explanation why you experience a difference in heating/cooling for your car, notice the length in the ducting passenger side vis-a-vis driver's side. Driver's side ducting is at least 1.5 times longer due to the positioning of the climate control system. Long ducting takes longer heating/cooling time, and of course blow pressure will decrease, the longer the duct is.

You are correct to say that evaporator does work. If anything, it is well possible that one of the blower doors isn't fully opening or closing.



* while on the subject and you are itching for something to do... when was the cabin air filter last changed? Cabin air filter serves as your air intake to your cabin blower. If restricted, it may also result in reduced blower efficiency.