Ok, so I have a crazy problem with my 2003 325i.

When the AC is on its coldest setting, it only blows cold air out of the forward facing vents if I also have either my feet or windshield vents going too. If I turn one of these two vents off, hot air blows through the forward facing vents.

I figure my heater valve is broken and stuck open?

To test this, I clamped the input hose to my heater valve and cranked it up...now I have cold air blowing from all vents. Will this hurt anything? I'm guessing I just need to keep an eye on my engine temp to make sure it doesnt cause it to overheat? Obviously, I'll have to replace my heater control valve at some point.



[Edited on May 24, 2011 at 9:41 PM. Reason : .]

5/24/2011 9:40:26 PM

SWEET 4 CYLINDER E46 IN THE US!!1

Ok, so I know this'll sound dumbo, but do you have the center air selector towards cold also?

5/24/2011 10:44:10 PM

Haha, yeah, the dial is on the coldest setting (three blue dots).

Not a dumb question at all...it's a really stupid design.

5/24/2011 10:49:17 PM

Is that diagram for reals, you have 4 hoses running to the heater core? One of which goes to the overflow tank? You're not hurting anything but your soul, -->obvious solution is to get a Porsche.

5/24/2011 10:51:07 PM

I dunno, I stole the diagram from an e46 forum.

::EDIT::
According to realoem.com, THIS might actually be my correct diagram.




[Edited on May 24, 2011 at 11:01 PM. Reason : diagram]

5/24/2011 10:56:38 PM

Basically, i clamped the #1 hose closed.

It seems that this would stop the coolant flow of the whole engine though...I'm gonna take the clamp off, and replace the heater control valve.

[Edited on May 25, 2011 at 11:56 AM. Reason : .]

5/25/2011 11:49:23 AM

Coolant circulates through the engine regardless of the heater core. The heater core just taps off some hot water for heating and returns it to the engine. You could take off the hoses and cap the ports on the block and your engine would be fine. If your engine is overheating without the heater core, then you've got bigger problems than hot/cold air in the cabin.

5/25/2011 12:04:42 PM

Oh word. I forgot that I was looking at a diagram of only the AC system. There's other coolant hoses on the engine other than these, right?

5/25/2011 12:09:43 PM

Correct, the heater core is only used to heat the passenger compartment. You will have a different process loop for the actual engine cooling through the radiator.

5/25/2011 12:28:33 PM

Gracias folks. I n00bed on myself a bit here, but I think i'm good to go. At least until it gets cold outside

5/25/2011 12:46:08 PM