cooling system/heat issue
 

i am helping my friend with his 85.5 944.

for starters, the cooling system was bled properly, with new coolant and distilled water.

the problem: the heat does not work, unless the defrost button is pushed.

turning the temp dial all the way hot does not get heat from the vents. however, when the defrost button is pushed, the car suddenly has heat at the vents.

any suggestions?

Check all your vacuum lines in the cab and in the engine bay.

Check your inside and outside temperature sensors to make sure they are working properly.

Next up, check that all of the little motors for blending the air into the HVAC system are working properly.

The electrical unit in the dash is supposed to read the temp inside and out then blend air accordingly to what your dial is set at. It uses both vacuum and electronic motors to control air direction and the heater control valve to obtain the proper temp.

my buddy had the same problem recently on his 89 844, after all the headaches of searching for vaccums and what not,it turned out to be this one little plastic clip that holds a rod that pushes the vent flaps,so that the heat or ac goes thru the vents,i was there when he found the problem for a minute.and it is under the dash on the drivers side if that helps you let me know.

that is what i was thinking, actually. i already checked the vacuum lines, but i'll definitely look at the other stuff.