Heating Issue

[sutpheme]

I have a 1999 M Roadster. Recently, I noticed that when my car is at idle, the blower will not put out hot air. I noticed this when I was stopped for a railroad crossing. It was putting out hot air before I stopped, then over about a minute it cooled off to outside air temperature. A few seconds after I started moving again, it blew hot air.

This does not happen with the air conditioning. Any ideas what might be acting up?

[Lord Vader]

Its possible your fan clutch has gone. I noticed this once in my E36. The fan clutch controls the main engine fan. If it is not working, when the car is moving air is pushed against it making it seem like it is working. When stopped the fan has no air to move it, and may continue spinning freely. One way to tell if you fan clutch has gone is take a rolled up newspaper and insert it into the fan while the engine is running. If the fan stops then the fan clutch is bad and needs replacement.

[sutpheme]

I checked the fan clutch, and it is still good. Any other ideas?

[Lord Vader]

Have you replaced any components of the heating/cooling system or added coolant recently? You could have air in your coolant system. Do you know how to bleed the coolant? Give that a try.