Coolant Warning Light when A/C?

[PirateZHP]

Hey everyone... When I first bought my ZHP, the coolant light would come on and off. After checking the coolant levels, and seeing everything was fine, I asked a few people who said the light(s) in older BMWs sometimes go on and off for no reason. Okay, no big deal then... Well, then it went away and was gone for a few weeks. I checked the level again to make sure it was using some sort of sick reverse psych on me (joke, of course), and everything was fine. Well, today is a rainy day here in Raleigh, NC... so I turned my A/C on. A couple minutes later, the coolant light comes on. I then realized that i haven't had my A/C on in a couple of weeks and that something must be triggering the light when the A/C is on. Any thoughts?

TLDR: The coolant level light comes on when the A/C is on: any idea why?

[danewilson77]

Most likely you're pushing an Air Bubble around in the system, and/or you have a small leak.

Recommend bleed.

Sent from my S4 > Mason, OH now Free

[PirateZHP]

Most likely you're pushing an Air Bubble around in the system, and/or you have a small leak.

Recommend bleed.

Sent from my S4 > Mason, OH now Free

And... how difficult is this? Something I should attempt?

[danewilson77]

Simple.

Raise front end of car.
Start car.
Set heater to 91°, fan in low.
Remove cap slowly.
Open bleed screw.
Add coolant until full, and don't overfill.
Shut bleed valve and install cap.

Someone can maybe point you to official procedure, but I should be close.

Sent from my S4 > Mason, OH now Free

[PirateZHP]

Sounds easy enough... I will see if I can work on that this weekend. Also, did you see the pics I put on my project thread about the front end links, Dane? You were asking about the removable ball joints, so I provided pics.

[kayger12]

I'd replace the coolant level sensor.

With the coolant system being the Achilles heal of these cars, I'd want to know that my sensor is functioning properly...

[PirateZHP]

Thanks. Is that something I should attempt myself as well?

[danewilson77]

Thanks. Is that something I should attempt myself as well?

Yes. It's in the bottom of the exp tank. Simple.

Sent from my S4 > Mason, OH now Free

[PirateZHP]

Sweet. I will see if we can get it done in the next week!

[alexandre]

Very most likely an air bubble.

The AC blows hot air when the wipers are on, no matter what, so it opened the heater core and the air bubble moved around.

So the light is actually gonna show up when you use heat (with or without AC)