Heating Issue

[Bimmer93]

Purchased an 93 525i, Can anyone give me an idea why when your sitting at an idle only warm air comes in then when you accelerate it goes up to a good heat, Water level is good so maybe a stuck thermostat also the temp. gauge indicates mid-range at idle then when on the road it drops down. THANKS

[Alexlind123]

^ Dat true.

[Karl]

Temp gage going low when the car is on the road indicates the thermostat stuck open.
But when you're at idle you don't get as much heat in the cabin because the water pump is not moving much water. It pumps more hot water thru the heater when the revs are up. My old e12 (pre climate control) is like that. But I don't notice it much in the e34.

[shogun]

idle only warm air comes in then when you accelerate it goes up to a good heat

auxiliary water pump out of order.