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Old 12-26-2009, 06:47 PM
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Bimmer750LI Bimmer750LI is offline
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Location: Reston
 
Join Date: Oct 2009
Posts: 291
Mein Auto: 750Li
If there is a slow leak and the system looses enough fluid then the heater stops working due to a air lock - sort of bubble in the system - preventing the flow of coolant through the heater core. When the leak/s are fixed and new coolant installed they bleed all the air out and run the heater to insure there is no bubble and that all systems are working and coolant is circulating properly. Of course it could also be one of the heater control valves not opening or the aux water circulation pump....dealer should be able to check for fault codes to determine if these are functioning to specification. Bottom line you need to bleed the system the correct way or you won't get the air pocket out and the heater and engine cooling will be compromised.
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