E36 328I HVAC not regulating temperature.

[tima 5]

Hi All,

(1999 E36 touring, 328I/A, NZ New) 

I'll say it from the outset, this is not the fan or fan speed regulator. The blower fan is 100% perfect.
My issue is heat. It will not regulate heat. 

-32*c blows HOT air.
-31.5*c blows cool non heated air
-Temperature slider thingi: makes no difference if on max or mid.

I took out the pollen filter and breathed in enough soot to probably get cancer from it. Blew out the filter and put it back in which gave me much better flow. 
I am not too sure what to check, I suspect it is electrical and a sensor in the HVAC box. The solenoid clearly works as I still get heat and good heat when on max, the system just seems to not know how to control the water flow to regulate heat and seems the solenoid is either open or closed. This is apparent for both climate zones.

Now for the curve ball, It seems to do this only in the morning and on the way home from work seems to regulate temperature OK. Maybe this is because the ambient temp outside is warmer and I am not able to identify the variance as well.

Any help is appreciated. If someone knows how to fix it I'll buy a box of their poison for the help. I am in Auckland North shore.

Side note: I have done 52,000KM in this car in 2 years, Never had a single failure or been left on the side of the road. This is the first thing wrong. 

Cheers

Tim

Edited August 23, 2018 by tima

[BM WORLD 1286]

gummed up sticky heater valve

also check the outside temp sensor is there and working

the flat round one ,

also clean the vent on the heater control panel

[tima 5]

2 hours ago, BM WORLD said:

gummed up sticky heater valve

also check the outside temp sensor is there and working

the flat round one ,

 also clean the vent on the heater control panel

Yup ill give the sensors a clean. Anyway to test with a multimeter?

*edit* I do not have a temp option on my OBC, Only date time and check control options. Does this mean I do not have an ambient temp sensor? 

Would a stuck heater valve still open fully and close fully? Cause I still get heat, I have had the stuck valve issue with an E39 and I had zero heat. Like the valve is still actuating. 

The little vent on the digi control panel on the front? Its free of dust etc but will get the compressor onto it tonight.

Cheers

 

Edited August 24, 2018 by tima

[BM WORLD 1286]

48 minutes ago, tima said:

Yup ill give the sensors a clean. Anyway to test with a multimeter?

*edit* I do not have a temp option on my OBC, Only date time and check control options. Does this mean I do not have an ambient temp sensor? 

Would a stuck heater valve still open fully and close fully? Cause I still get heat, I have had the stuck valve issue with an E39 and I had zero heat. Like the valve is still actuating. 

The little vent on the digi control panel on the front? Its free of dust etc but will get the compressor onto it tonight.

Cheers

 

no its a outside temp sensor mounted in the brake duct on rhs I think , tells the heater unit .

valves , just open it up and check it out

[tima 5]

2 minutes ago, BM WORLD said:

no its a outside temp sensor mounted in the brake duct on rhs I think , tells the heater unit .

valves , just open it up and check it out

Thanks Brent,

 

Will give it a go this weekend if I make it out of bed! 

[tima 5]

So I did a coolant change and this issue has not come back since. Strange.
Must have had an airlock in the solenoid or something.