Re: What could be wrong with my slow heater? (archive)

I was talking about the time it took to start producing heat- not the amount of time it took to get the cabin warm. Just making sure we're on the same wavelength.

You can force maximum heat by unplugging the electrical connector from the heater valve. On 533i/535i models, the valve is located on the firewall, more or less in front of the driver. It has a square top held on by four screws.

If you've suddenly got gobs of heat after removing the connector, then there's some control problem:
-bad heater switch
-bad interior temp sensor
-bad heater core sensor
In this scenario, plug the connector back in and turn the heat up all the way, which I assume is how you normally run it. This is supposed to bypass the control loop and open the heater valve regardless of what the sensors say to do. If it doesn't you have a bad heater switch. Bummer.

If heat is still inadequate after you unplug the valve, here are the possibilities:
-blocked hose.
-bad heater valve.
-bad heater core.
A bad heater valve seems to be common with e28 cars. A rebuild kit costs around $30 (not from the dealer, though!) and is usually simple to install. There have been a lot of posts recently on how to do this.

I'm talking about the time it takes for the cabin to heat b/c mine seems to take a long time to warm up--any idea on what could be wrong?

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