Ok folks, lately my heater has been blowing cool air intermittently. It would blow hot for a while and then cool down and stay cool for awhile. I have my climate control all the way up to 80 or whatever the highest setting is and I've tried in in Auto as well as manual fan mode. I also made sure the setting in my i-drive was all the way red. The cool air is coming from all the vents as well as the floor vents.

I checked my coolant level and that seems to be fine. I'm wondering if it might be a thermostat problem and just needs a new thermostat maybe?

Either way, it's out of warranty and I would like to try and diagnose it myself and not have to go to the stealership unless I have to. I'm hoping it's a thermostat and not a heater core or something of that nature. I've checked my garage spot for any coolant leaks and there are none.

Just curious if this has happend to anyone or if anyone has any insight on this? Perhaps a DYI on a thermostat? Oh, I have drive a 2005 530i w/ 60k miles.

Any help would be greatly appreciated!!!

Thanks!

 

I don't know if the '05 model still has the moving lines at the end op the rev-counter.
If so, you can see if the engine is heating up at all.

Start the car from cold (let it sit for at least 6 hours, preferably do this in the morning) and watch the lines.
Start driving and drive for at least 5 miles. If the lines don't go up (i don't know the exact rev-range of a 530i) to about 500 revs under the red line, your thermostat is dead.

 

I had that problem, it was due to a dead battery cell. I replaced the battery and it was fine.

 

Just be very careful with it, dont want any of your pipes going pop and steam pouring all over the place! Get a diagnostics check done on it asap!

 

If your sure your coolant level is correct (did you check after the car has been sitting overnite?). Next step would be thermostat. Usually when you have an issue with that the air will be semi warm and just never get hot. You need to be driving a good 15 mins. or so. If you driving just 5 mins away and turning the car off chances are it won't warm at all with a stuck open thermostat. Its an under $20 DIY repair. Might work might not.

After this if it isn't fixed your looking at an issue with either of the following heater core or software/electronics.

A good independant shop should have no problem fixing this issue for a reasonable amount. Dealership will rape you big time.

 

You may have a broken AC regulator E60 Driver.

It's a type fault and I have had it once on my '01 E39 525iA and twice on my '05 E60 525iA.

But then the heat was always on, a bit.

 

in my maxima, it was low on coolant. when i would drive, the hot coolant would circulate through the heater core and provide me with warmth... when i would sit at a red light at idle, it would get cool. when i reved the engine and circulated coolant, it would get warm again.

moral of this story is... check your coolant.

 

Mine was just in the shop with similar problems with low heat. They changed the thermostat and all was well. I have a 2004 530i with 47,000. Hope this helps.

 

Thanks for all the help and suggestions!!!! I think I will have a chance to look at it more closely this weekend and I think I'm going to start off by replacing the thermostat first and see if that helps!

 

Wait...what