Cabin heat problem 1997 528i. Help winter is here and I am cold

[Heyobie]

The heat inside the cabin is acting up. The heating system is blowing cold air when it should be pushing heat. But then sometimes, warm air will start coming on. But it is working wrong more than it is right

Could be the internal heat sensor?
Could be a valve that is not opening?
I don't think it is the final stage unit. I believe that controls the fan and I have replaced the FSU a couple years ago

Any help is appreciated.

Thanks,

Obie :buttrock (me shivering)

[JimLev]

When's the last time you checked the coolant level in the expansion tank? Sounds like it could be low.

[Cobra1956]

I agree with Jim. Start simple. Your car can run @ 1/3 down on coolant. You will loose heat before it overheats. This can be caused by slight leaks from your cap. Rather than your system working normally you slowly suck air into the top of the system or directly back into the radiator rather than coolant back in as the pressure subsides. Try bleeding your system with more of the proper mix and report back. System turned to heat of course.

[Heyobie]

OMG. It never crossed my mind. Went out and it was low. Filled it up. Driving to work and will let you know.

Embarrassed

[JimLev]

Haha, your the second one this week with the same issue.

[Heyobie]

I filled it and bled it. It took about a 2 quarts. Went to work and it wasn't much better. It then began to overheat. Check engine light on. Can't believe I made it worse by adding fluid. I then filled it again and bled it and this time it took about a gallon and a half. Now she is real happy and heats like a motha.

Thanks guys. I have had lots of cars over the years, but the BMW is the only one that likes to lose water in a sneaky way and has to be bled.

Thanks again. Obie (The Hot Guy)

[JimLev]

If you do have a slow leak I'd check it every day when cold in the moning, add coolant as necessary, then you won't need to bleed it.
Find the source of the leak when you have time.

[Heyobie]

Good advice. Thank you