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Discussion Starter #1
Hey looking for some direction on solving issues with heat in my 2007 BMW 328xi

Let's start at the beginning. My car started overheating on longer drives in the summer. I replaced the thermostat but the problem persisted. I started to think I had a blown head gasket and put "blue devil sealant" in. That didn't work. Then I replaced the water pump (this seemed to do the trick, although old one worked it did not run as smoothly when testing with incremental electric pulses on battery) and I acid washed the radiator. I was back in business for the summer and the car no longer overheated.

Fast forward to start of Fall when it starts getting cold out. Go to turn on the heat and it's not working. I had weak warm air on drivers side vents and it just got colder as you run your hand to furthest passenger side vent. Looking on forums I diagnosed as heater core clogged from the blue devil sealant that was put in the system. So I flushed it...and flushed it... then more. The blue devil had clumped together and I saw it coming out. I thought I found my problem. So I followed the lines and disconnected by firewall to backflush heater core with some air and water and smidge of CLR cleaner. I had water coming out both hoses clean and clear. Put it back together and the heat came back strong on drivers side... but still cold on passenger.

Decided to get it scanned thinking electrical. Dealer wanted $175 to scan (pound sand dudes). Found a guy to do it for $60. While he scanned i moved dials. He said the passenger side blend door actuator motor seemed to be moving too quickly in comparison to drivers looking at computer.

Took it home. Took out glovebox and see actuators. Move dials again and see each one moves the rod that would move flaps or doors. Scratching my head baffled because the actuator motors seem to be doing their job and the flaps seem to be moving. Still no hot air on passenger side.

What am I missing? Or what should I be checking next?
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 100K miles NOKIAN WR G3 20K miles
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19,408 Posts
On late model X5 the AC is always fully loaded and temperature control is by a dual heater control valve throttling engine hot water to left and right heaters after the AC evaporator. Heaven knows what the Devil did to the internals of the dual valve.
 

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Discussion Starter #5
That was my thought, but I thoroughly washed out the system backflushing with water, CLR cleaner, and controlled bursts of air pressure. I have a smooth flow of water coming in and out of hoses.
 
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