Brrrrrrr N-n-n-n-no h-h-h-h-h-heat

[Huw Powell]

> Those are my teeth chattering in the subject line.
> 
> My 89 80 4 cyl occasionally has heat coming out the defroster vent, 
> rarely has heat coming out the dash vent, and never has heat coming out 
> of the floor vent.  Even if, for instance, heat was in fact coming out 
> the defroster vent, if I turn the air output selector knob to floor 
> output no heat comes out, although the air starts blowing out of the 
> appropriate location.  I find this very peculiar.

Me, too.

> I took off the heater hoses from the engine, and ran water from a hose 
> through the heater core, seems to have no restriction to flow.  I made 
> sure the system was full by removing the coolant temp sensor while the 
> car was running cold, then let it heat up, some air came out, but the 
> heat doesn't work any better.

So the heater core really, really allowed easy water flow?

Doesn't your car have a vent screw on top of the radiator to bleed the 
air out?  That sender isn't really high enough, IMO.  Oh wait, I am 
thinking the 5 cyl. set up here...

> While I was waiting for the sheets of ice to melt off my other car, I 
> had opportunity to look at the 89 Audi 80 heater situation again.  The 
> reservoir was empty (?)  but I filled it up again.

Probably displacing some air that was left in there...

> I went under the hood, and felt all the hoses.  All the hoses are 
> pressurized and hot to the touch - except one of the heater lines is 
> cool to the touch (the other is the same temp as the rest.)  Is there 
> some type of heater valve in under the dash?

On the type 89, there is no heater valve, as previously noted.  Air 
supply is controlled by the temp knob running a flap.

So it sounds like you actually have *two* separate problems - one, 
little or no flow through the heater core when the engine is running, 
and two, something really weird wrong with your knob control cables. 
It's like when you change the location for the air to come out, it also 
changes the temp mix of incoming air.

Anyway, I'd attack the coolant flow issue first.  Could your t-stat be 
stuck open or closed?  Could a heater hose be clogged where you weren;t 
testing it?  I know it's lousy weather for it, but a good thorough flush 
might be in order.  On the 4 cyl, the water pump is outside the engine 
block, right?  You might want to give that a look-see.

Then, pull the heater control panel (pull off knobs, undo screws, hit 
with big hammer) and see how the cables look.  You may have to dig in a 
bit to figure this one out.

Good luck, and let us know how it turns out...

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/