Where's the warm air? - The Unofficial BMW M5 Messageboard (m5board.com)

jajo · 3rd December 2008, 08:18

Hi everyone.

I have run across a problem in my 2002 M5.

I have no heat.

While my heat is turned on, I can BARELY feel the heat. I can turn it on full blast, but I can still barely feel the heat.

Does anyone know what's going on here? My coolant is fine, and I know it's blowing slightly (but not a lot), but it is not even enough to get the car warm. This has been going on for the last two weeks.

I hope I can get some help.

Thank you
Jajo

MarkQC · 3rd December 2008, 10:30

Please specify what vents are doing what...

Remember the front middle vents will blow cold, unless you change the mixture manually...

Mike Krieger · 3rd December 2008, 18:22

Is this a fan question or a temperature question? If it is the fan, then search for second stage resister etc.

jajo · 3rd December 2008, 20:57

thanks for the responses.

The air doesn't feel like it's blowing anywhere, even if it's set on "max."

I even looked to see if it was a fuse to no avail. It is listed as fuse 76 which was not there. Do you think they put that fuse somewhere else other than the glvebox since it's 40v?

TMcNasty · 3rd December 2008, 21:26

Well if your fan motor won't blow any air then you probably have the bad fan resistor problem commonly referred to as the final stage unit or FSU.

If your fan is working properly then your center vents could be set to "cold" vs. "hot." Take a close look and notice the thumbwheel in the very center. If this is rolled towards three blue dots instead of three red ones that's part of your problem.

Finally, and quite possibly, you have a bad thermostat and your entire motor is running cool. When that happens hot water to the cabin is greatly reduced creating only lukewarm air for you.

To test for condition three follow these instructions and run test #7.

Gadget Freaks II: Fun you never knew you could have [secret menu]

If the reading goes below 79c after the car is warmed up then your thermostat is faulty. Easiest way to test it is at highway speeds. The increased airflow over the radiator at speed will show the thermostats condition quickly.

everycredit · 3rd December 2008, 22:32

Drive your car in Hawaii. Weather is fine and plenty of warm air. No warm air here in Seattle.

To answer your question, read TMcNasty's post.

jajo · 3rd December 2008, 23:50

tmcnasty, thank you for the suggestions.

When I turn the heat on, it sounds like everything is about to start. But, I hear no fan blowing.

I know it's not the center vent hot and cold switch. I've had the car going on six years so I know about that LOL.

Can the FSU be changed at home or should I take it to the dealer? Thank you for all the help so far. Oh yeah I think the thermostat is fine. The engine is running warm according to the dashboard.

Everycredit, I would love to be in Maui or kauai right now.

KJM5 · 4th December 2008, 00:12

You can change it out. I did mine. Takes about 15 minutes. Search the forum for a DIY.

TMcNasty · 4th December 2008, 01:44

Quote:

Originally Posted by jajo

Can the FSU be changed at home or should I take it to the dealer?

Haven't had to change one myself, but there are DIY threads on this board. Small hands help w/ the swap.

Need4Spd · 4th December 2008, 05:04

Most likely a FSU if no fan activity at all. If fan blowing but you are not getting hot air, a possibility is faulty heater pump. Small unit under the hood somewhat beneath the oil filter canister.