E90 335i Dual Zone Climate Control Wierdness

RayLivingston · 10-07-2018, 03:27 PM

The climate control on my '07 335 has not worked right since I bought the car about 4 years ago. It appears to me perhaps one or more dampers are not moving freely. The most persistent problem is after starting on a hot day, the A/C often pumps out actually HOT air, and also often runs the fan at much higher speed than necessary. I've found I can usually coax it into working more correctly by simply setting the A/C to MAX for a few seconds. It appears to me either the compressor is not turning on, or, more likely, the damper that controls the heat is stuck open, and setting to A/C MAX somehow gets it to a working state. Once it's coaxed into working, it works more or less OK.

So, my question is: How difficult is it to get access to the HVAC box to check operation of the (as I understand it) 8(!) stepper motors that control the dampers, etc.?

Regards,
Ray L.

e90yyc · 10-07-2018, 04:04 PM

Do you have INPA, cable and a laptop?

I would start by troubleshooting using software to cycle the flaps/actuator motors and look for issues. INPA will tell you to what degree each is open, and also allows you to run a calibration sequence (calibration likely won’t help you but you never know).

You can also see whether the compressor is switching on.

I’d highly highly recommend going this route before pulling things apart.

Let me know if you need more info.

G’luck

RayLivingston · 10-07-2018, 06:14 PM

That's a good point - I hadn't thought of that. I don't have INPA, but do have a Foxwell ODB tool that can access the test modes. Just used it today to test the injectors in my 325i.

I'll give that a shot, and report back.

Thanks!

Regards,
Ray L.

10-07-2018, 03:27 PM	#1
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	E90 335i Dual Zone Climate Control Wierdness The climate control on my '07 335 has not worked right since I bought the car about 4 years ago. It appears to me perhaps one or more dampers are not moving freely. The most persistent problem is after starting on a hot day, the A/C often pumps out actually HOT air, and also often runs the fan at much higher speed than necessary. I've found I can usually coax it into working more correctly by simply setting the A/C to MAX for a few seconds. It appears to me either the compressor is not turning on, or, more likely, the damper that controls the heat is stuck open, and setting to A/C MAX somehow gets it to a working state. Once it's coaxed into working, it works more or less OK. So, my question is: How difficult is it to get access to the HVAC box to check operation of the (as I understand it) 8(!) stepper motors that control the dampers, etc.? Regards, Ray L.
	Appreciate 0 Tweet Quote

10-07-2018, 04:04 PM	#2
e90yyc Art Collector 2427 Rep 3,450 Posts Drives: 2007 328xi (GM-delete 6MT) Join Date: Feb 2018 Location: Canada iTrader: (0)	Do you have INPA, cable and a laptop? I would start by troubleshooting using software to cycle the flaps/actuator motors and look for issues. INPA will tell you to what degree each is open, and also allows you to run a calibration sequence (calibration likely won’t help you but you never know). You can also see whether the compressor is switching on. I’d highly highly recommend going this route before pulling things apart. Let me know if you need more info. G’luck __________________ When I'm dead, just throw me in the trash.
	Appreciate 0 Quote

10-07-2018, 06:14 PM	#3
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	That's a good point - I hadn't thought of that. I don't have INPA, but do have a Foxwell ODB tool that can access the test modes. Just used it today to test the injectors in my 325i. I'll give that a shot, and report back. Thanks! Regards, Ray L.
	Appreciate 0 Quote