E46Fanatics - View Single Post - A/C blowing @ different temps from vents..
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Old 05-19-2008, 09:21 PM   #19
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Join Date: Apr 2002
Location: Tampa, Florida
Posts: 601
My Ride: '02 BMW 330Ci
Originally Posted by BMWF18 View Post
Easy way to check you water valves is to turn on your a/c and grab the hoses going to either side of it. If they are both hot, and your heater is not on...It failed open. If the problem persist, you might have a leak on your evaporator or some other component.
To elaborate some on checking your water valve (heater control valve, which controls HEAT): turn your climate control to max cold, a/c on or off, it doesn't matter. down on on the driver side wheel well there is a little round tin can with a connector attached to it with two wires coming out (behind it going toward the cabin are two hoses you can't see. With the engine warm, it should feel ambient warm, not more. If it is screaming hot then hot coolant water is travelling through it when it should not be. To verify, take mental note of the temp of that sucker, then go turn the heater to max hot. The temp should remain relatively the same if the HCV is not functioning properly.

I'm uncertain if this is the actual "bmw method" of verifying if if this is open or not, I call it the poor-man method, because all you need is your hand to diagnose it
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