Heats cabin as if there is no tomorrow

I have a problem with automatic climate control on 2003 330xi. It always blows hot (very hot) air.

This is my first bimmer and I haven't had it for very long to know how it should work. But it cannot be right. Whenever I turn the air it always blows a really hot air.

I tried to put it on auto, on manual, all different vents, different temperatures. No difference. It blows from correct vents, but always hot air. I put it on auto on 75o when outside was over 90o - it is still heating!

The only exception is if I turn AC - then you can feel how AC and the heater are fighting each other and the air comes out only warm.

In dry weather, it is ok - I keep it off and open the windows. But if it is a pouring rain, it is bad - once I turn the defogger, the temperature in the cabin goes over 100o within minutes.

I don't know if it is related, but my central console is always hot (no matter if the fan is on or off). I keep quarters in the ashtray and they get really hot to touch.

What could it be?

Thank you!

I would guess its your heater control valve. Also called water control valve. Its a 70 dollar part behind your airbox. Recommend searching those key words. It's an easy DIY.

Sent from my PC36100 using Bimmer App

You have turned the little thumbwheel between the two center vents all the way to cold (blue dots) haven't you? Took me a while to figure that out when I got my car. Also, my defroster always runs full blast, maximum hot. Annoys me too

Originally Posted by mlukas161

I would guess its your heater control valve. Also called water control valve. Its a 70 dollar part behind your airbox. Recommend searching those key words. It's an easy DIY.

Sent from my PC36100 using Bimmer App

Second that.

Originally Posted by jimvideopro

You have turned the little thumbwheel between the two center vents all the way to cold (blue dots) haven't you? Took me a while to figure that out when I got my car. Also, my defroster always runs full blast, maximum hot. Annoys me too

A simple one to overlook, so definitely try this (free) one first.

If you plan to keep your car and work on it yourself, a Bentley Manual is a good investment. Most of the info below is from the Bentley manual.
http://www.bimmerzone.com/BMW_Servic.../BNT-B305.html

You could get the codes read from the IHKA system. These codes do not turn on the SES/Check Engine lights as they do not cause an increase in exhaust emissions.
A BMW Dealer or good independent shop should have the software to read the codes as well as monitor the values of the sensors, the opening of the water valve can be monitored, the AC condenser temp, high side pressure etc.

What does your outside temp display? The Ambient Temperature is used by the Heating and cooling system. If the IHKA gets an invalid or no input from the Ambient Temp sensor it uses a default value of 0F for the outside temp.
If the IHKA thinks it is 0F outside, it will try to bring in cool outside air to cool the car.

There are a couple of temp sensors for the heat/AC, one for the evaporator and one for the heat exchanger.
If the evaporator sensor fails or is disconnected, the IHKA uses a default value of 32F for the input. The compressor will not run if the evaporator is at 32F. Both of these are the same part number so they can be switched for testing.
Evaporator Temp Sensor:
http://tis.spaghetticoder.org/s/view.pl?1/07/27/73
Heater core temp sensor:
http://tis.spaghetticoder.org/s/view.pl?1/05/63/76

There is also an interior temp sensor. If it fails the IHKA defaults to using a temp of 68F.
If you get better cooling when you lower the temp setting below 68F, you might suspect this sensor.

Thank you for the suggestion! That's probably it. Will try to replace the valve.

I suppose there is no way to make sure it is the valve before getting one, since it could not be returned being "an electrical part"?

Warm up the engine, turn on A/C and touch the hose after the valve. If it is hot - the valve is bad.

The outside temp display looks correct.

The cooling is not the problem though (at least as far as the cooling could be noticed). The problem is the heater that would not stop.

Yes, I have adjust the blue dots on the little wheel. No difference that I could tell. Plus it blows just as hot air on the windshield, if I turn it to auto.

I've got the Bentley and will try to check error codes reading.

At the same time, the rear window defroster works only when the IHKA fan is running. Which seems strange to me since the rear window defroster is just an electrical heater on the glass and should have no relation to the fan.

I have replaced the heater control valve following this excellent DIY: http://www.e46fanatics.com/forum/sho...d.php?t=617301. (Just be careful tightening the bleed valve - I snapped mine.)

Unfortunately, it did not help. I have looked at the error codes, and it said something like "short circuit to the ground". So I decided to take it to the dealer to diagnose.

The dealer claims that it the climate control computer that needs to be replaced.

Originally Posted by AT01

I have replaced the heater control valve following this excellent DIY: http://www.e46fanatics.com/forum/sho...d.php?t=617301. (Just be careful tightening the bleed valve - I snapped mine.)

Unfortunately, it did not help. I have looked at the error codes, and it said something like "short circuit to the ground". So I decided to take it to the dealer to diagnose.

The dealer claims that it the climate control computer that needs to be replaced.

Sorry to hear that the valve didn't fix the problem. Climate control computer sounds expensive. Let us know how you make out.

To Verify the valve is open(stuck, or commanded electrically), clamp either of the hoses coming off the valve. This effectively shuts off water flow through the heater core. If your ac blows cold in this configuration, the valve is remaining open. Maybe that short to ground is the problem, good luck-