Strange Heater Problem

[kitchman]

Hello again,
I have noticed recently on my 82 Cressida that the heater turns cold when going up hill. The temperature gauge does not change and when the car levels off the heater returns to normal. Was thinking that perhaps there is some sort of air entrapment in the system?
Any one experience any thing like this?
Thank you in advance

[kamesama980]

It's likely that when going uphill when you open the throttle to maintain speed you don't have enough vacuum being generated to keep the hvac flaps in place since they're actuated by vacuum servos. check for vacuum leaks in the HVAC plumbing, reservoir/generator (don't know what the x6 has) and check valve

[chuck616]

I'd like to know what you find out on this. My '85 does the exact same thing. The heater works fine around town, but when I need to accelerate, the heater blow cold air.

[kitchman]

Hello there,
To bad your having the same problem. I have not had a chance to look further into this yet. Hopefully it will warm up a bit and I will have a closer look. If I find out some thing I will post it.