High Temp light coming on only when running AC or Heater

Don't tell anyone about that special pump cycle test I let you in on. It's secret mechanic stuff.

haha, no problem. mums the word.

So i drove home today from work and set the climate control at 76 and set the fan speed on auto. after about 1-2 minutes i started feeling warm air coming out of the top vents. The vents facing directly toward me either had no air coming out, or slightly cooler air. The warm air stayed on for about 5 minutes and then started getting cooler. I then came to stop light and noticed my radiator fan was running at max speed, so i stopped and checked the radiator temp and it was blowing out cold air, so no circulation through the radiator. I turned the heat off at this point and drove the rest of the way home (about 5 minutes). i got out and checked the engine, and it was cool enough to touch, and the radiator fan wasn't on.

Then while the car was running i turned the heater on max and then loosened the bleed screw a few times to let some bubbles out. Then shut the car off.

Originally Posted by gerrg

haha, no problem. mums the word.

So i drove home today from work and set the climate control at 76 and set the fan speed on auto. after about 1-2 minutes i started feeling warm air coming out of the top vents. The vents facing directly toward me either had no air coming out, or slightly cooler air. The warm air stayed on for about 5 minutes and then started getting cooler. I then came to stop light and noticed my radiator fan was running at max speed, so i stopped and checked the radiator temp and it was blowing out cold air, so no circulation through the radiator. I turned the heat off at this point and drove the rest of the way home (about 5 minutes). i got out and checked the engine, and it was cool enough to touch, and the radiator fan wasn't on.

Then while the car was running i turned the heater on max and then loosened the bleed screw a few times to let some bubbles out. Then shut the car off.

What we would do next is check for power to the pump when it is not on. If there's power you know it's the pump. In your case all the evidence points to the pump and you'd take a calculated risk in changing it. As others have posted, and my internet checks confirm, it is usually the pump. Did you check for codes?

No, i didn't get the codes. i got the car diagnosed at the bmw dealer, but they didn't give me any codes (this was done before you mentioned them) I might be able to call them back and get them, but i think right now i'll just go ahead and order the pump and see if that fixes stuff. I was going to change the Tstat anyways, so i guess i'll just do both at the same time. My guess is i should have parts by next monday or so, so that'll give me a few days to change them. If you have any other ideas, let me know. Thanks a bunch for your help, and i'll let you know how it goes!

Originally Posted by gerrg

No, i didn't get the codes. i got the car diagnosed at the bmw dealer, but they didn't give me any codes (this was done before you mentioned them) I might be able to call them back and get them, but i think right now i'll just go ahead and order the pump and see if that fixes stuff. I was going to change the Tstat anyways, so i guess i'll just do both at the same time. My guess is i should have parts by next monday or so, so that'll give me a few days to change them. If you have any other ideas, let me know. Thanks a bunch for your help, and i'll let you know how it goes!

Do you have the manual so you know how to go about the job? If not, I'll pm you the info. as an attached file.

Originally Posted by DSXMachina

Do you have the manual so you know how to go about the job? If not, I'll pm you the info. as an attached file.

Come on! There's a standard procedure for this.

1 ) Have a beer.
2 ) Go down cellar, gather tools you expect to need.
3 ) Have another beer.
4 ) Go out to car, locate part that needs to be replaced.
5 ) Go to have another beer, accidentally spill it into engine compartment.
6 ) Swear.
7 ) Apologize to neighbor for swearing in front of 5-year-old.
8 ) Have another beer.
9 ) Start to remove part, realize you're missing the right wrench.
10 ) Swear quietly.
11 ) Go look for wrench in cellar, can't find it.
12 ) Swear loudly in cellar.
13 ) Have another beer.
14 ) Use slip joint pliers on stuck nut.
15 ) Round off nut.
16 ) Storm into cellar, get Vise-Grips.
17 ) Guzzle another beer on way back to driveway.
18 ) Place Vise-Grips on nut, lean in with all weight, hit release pin on Grips, remove all skin from knuckles.
19 ) Swear again, not giving a damn about neighbor's pain-in-the-ass kid.
20 ) Stand up too fast, hitting head on inside of hood.
21 ) Storm into house, swearing continuously.
22 ) Decide to go lie down for a bit.
23 ) Wife calls garage while you're asleep.


At least, that seems to be the standard at my house.

Originally Posted by DSXMachina

Do you have the manual so you know how to go about the job? If not, I'll pm you the info. as an attached file.

No, I don't have the manual. I was going to use a modified version of zooks procedure, mixed with some DIY pictures here on the forum here, but if you could send me that, that would make things a lot easier. Thanks a bunch!

Originally Posted by Zooks527

Come on! There's a standard procedure for this.

1 ) Have a beer.
2 ) Go down cellar, gather tools you expect to need.
3 ) Have another beer.
4 ) Go out to car, locate part that needs to be replaced.
5 ) Go to have another beer, accidentally spill it into engine compartment.
6 ) Swear.
7 ) Apologize to neighbor for swearing in front of 5-year-old.
8 ) Have another beer.
9 ) Start to remove part, realize you're missing the right wrench.
10 ) Swear quietly.
11 ) Go look for wrench in cellar, can't find it.
12 ) Swear loudly in cellar.
13 ) Have another beer.
14 ) Use slip joint pliers on stuck nut.
15 ) Round off nut.
16 ) Storm into cellar, get Vise-Grips.
17 ) Guzzle another beer on way back to driveway.
18 ) Place Vise-Grips on nut, lean in with all weight, hit release pin on Grips, remove all skin from knuckles.
19 ) Swear again, not giving a damn about neighbor's pain-in-the-ass kid.
20 ) Stand up too fast, hitting head on inside of hood.
21 ) Storm into house, swearing continuously.
22 ) Decide to go lie down for a bit.
23 ) Wife calls garage while you're asleep.


At least, that seems to be the standard at my house.

Nice! If I were ever to attempt my own repairs, this is surely how it would go. :-) Although, I would probably up the beer intake just to be safe.

got all parts on order, should get everything on tuesday. fingers crossed.

Just an update. Got my parts in last week and changed the water pump and Tstat. Since then, my heater has worked just fine and my car hasn't had any issues. Thanks a bunch for everyone's help with this! It is definitely appreciated!