BMW 3-Series E46 (1998 - 2005) - Cold air from the heater

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Fri 16 Nov 2007 20:52
Cold air from the heater - david50leaf
I have a late 1999 (v reg) BMW 3 series 1900cc with 20,000 miles and the heater only blows cold air. 12 months ago I noticed the temperature gauge was eratic but it settled down to normal range. What is the problem?
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Sat 17 Nov 2007 10:05
Cold air from the heater - L'escargot
To do-it-yourself you need the be methodical and trace things from source to output. For example, is the coolant feed to the heater hot?
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L\'escargot.
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Sun 18 Nov 2007 14:04
Cold air from the heater - GandA
It could be that after the warmer weather of "summer"? the heater control linkages have got a bit sticky and the valve isn't opening to allow hot water through to the heater rad. Not easy to get to as these bits are usually well hidden under the facia/ dash etc. Check that the levers do move when the heater controls are moved from cold to hot. Sometimes a LIGHT tap from the end of a screwdriver can free thing up.

It could also be that you have some muck floating around in the system that has collected in, and blocked, the heater radiator. I had similar problems several years ago. Try a drain down, refill and drain down again. If this doesn't clear the problem you might consider putting a flushing agent into the system but BEWARE. All the flushing products loosen EVERYTHING in the waterway and you could end up with leaks all over the place if the radiators are held together by corrosion !!
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