911 2

my 1991 964 does not blow any air from the right hand side screen vent the left passenger side is fine
if i turn the temp **** right down it does start blowing from both vents, any idea what is wrong as driving the car is becoming a nightmare a one i have racing headers so minimal warm air and two the vent not blowing any air is causing the screen to mist up

Eric Kessel

The passenger side blower motor is probably seized up.

911 2

i didnt realise there were two motors
if it was seized where is the sir in the driver side screen vent coming from when i turn the temp **** right down to cold

Eric Kessel

Excellent question about the change in temperature. I had an issue where the air was only blowing on the passenger side (truthfully I don't remember the temp settings, but it was definitely when I pressed the defog button). It was also causing blown fuses to the ccu controller. I tracked it down to the passenger side blower. (I used a meter to check the draw on each blower, which required pulling pins off the large connector under the hood.
I hope this helps......

Rocket Rob

Could something be obstructing that vent? Do you get air out of the driver side when the heat is on?

911 2

the heat is not very good as i have racing headers, the vent does blow air from the driver side when i turn the heater **** to full cold ie 7 oclock position, htis also causes the left bower to switch on

911 2

any ideas dnt know what to take off motor, servos

Rocket Rob

I would first inspect your servos before checking the fan motors. The servos are easy to access. http://porsche964.co.uk/technical/servos.htm

To replace/inspect the fan motors, follow this thread. https://rennlist.com/forums/964-foru...s-blowing.html

911 2

I cant see the servo arms moving they seem to be both at around 5oclock, if this is the problem then why is the passenger side one working.
i was under the understanding the servos controlled the heat and not the air flow

Eric Kessel

Have you had the CCU checked for codes? The servos control the airflow which does control the heat (they open/close the flow from the rear of the car). The servo motors are pretty poor little gizmos, and do go bad, so it's possible one is dead.

Have you had any luck checking out the blower motors? If you are good with a meter, I can post a few pictures of what you can check on the power connector to the blower motors, to see if one is seized.......

911 2

eric that would be great im good with the meter if you can give me some guidance,
what i cant understand is if the servos are bad wouldnt they let air in just a matter of whether its cold or warm, im getting nothing, the only time both vents give air is when the aircon is on and the heater control is on coldest setting ie at position 7o clock

Eric Kessel

Have you checked the fuse for the rear blower? It is used during heating, and has been known to cause issues whenever the temp is raised up off the blue dot setting... You can search on "blue dot" and should find a pile of info.

I'll try and put together some info on the front blower current tomorrow.

911 2

cheers

911 2

eric any luck with the info on how to check the blowers