blend door question

[stackz]

2001 3.0 with the basic 3 knob a/c controls.


is the main blend door vacuum operated?


past two days when I'm at a stop, I lose all heat. once I start driving it comes back so I'm thinking the blend door (if vacuum operated) must be starting to fail (probably internal diaphram). does this sound about right?

[Qsilver7]

Here's just one (FUB) explanation of the IHKR system used on the e53/e46/e39 semi-automatic system (that uses the dials and bowden cables): https://www.newtis.info/tisv2/a/en/e...bution/X8tx6rN



And connecting pin X611 (on back of the IHKR)...pins #7, #8, #9, #10 operate the fresh air flaps...which would indicate that the flaps are electronically actuated:

Pin assignments at plug connector 4 X611

Pin Type Description /Signal type Connection /Measuring notes

• 1 A Sensor signal Left heat exchanger sensor
• 2 A Sensor signal Right heat exchanger sensor
• 3 A Sensor signal Evaporator sensor
• 4 A Signal Output stage Output stage
• 5 Not used
• 6 E Sensor signal Sensor connector
• 7 E Actuating signal Fresh air flap motor Fresh air flap motor
• 8 A Actuating signal Fresh air flap motor Fresh air flap motor
• 9 A Actuating signal Fresh air flap motor Fresh air flap motor
• 10 E Actuating signal Fresh air flap motor Fresh air flap motor
• 11 Not used
• 12 Not used

[stackz]

ok, so that eliminates vacuum as a possibility. hmm. I wonder why its doing this at idle then since its electronically controlled. time to start searching.

[Qsilver7]

I have this old info (below) that was specifically for the e38 with the IHKA (fully automatic) system. But since the e38/e39/e53 share many design commonalities...although this is for an upgraded system...the fresh air flaps probably still have some type of set-up to compensate for more air coming into the system the faster you go which would mitigate the ram air affect. The IHKR systems in the e39 & e53 may not vary the "blower speed" but I bet there's something affecting the position of the fresh air flaps based on speed. What that would be, I don't know (yet).


FYI:

[80stech]

That sounds like low anti-freeze, head gasket, water pump.

[stackz]

Originally Posted by 80stech

That sounds like low anti-freeze, head gasket, water pump.

I dont know why it didnt dawn on me to check the coolant, yup! its definitely low.



any special type I need to use or can I just get the standard green stuff from the parts store pre-diluted?

[stackz]

I just grabbed some prestone for european cars. took almost all of it. now I have heat again. now to figure out if I have some sort of slow leak or whatnot.

[Overboost]

Love the easy fixes!

[80stech]

An often overlooked slow leak is the temp sender on the lower rad hose.

[Overboost]

Originally Posted by 80stech

An often overlooked slow leak is the temp sender on the lower rad hose.

Yep, that one was leaking on mine a year ago. I replaced the entire hose with sensor.