Hi,

I’ve tried search and also read Wally’s excellent document about the 928 Hvac systems, but unfortunately the symptoms my system as developed don’t fit in any of the usual Hvac problems.
This is my situation:
If I put the Programme lever in any of the positions other than 0, whether Eco, Automatic, Defrost, etc I start hearing a constant buuuzzz, like the fan is working very slowly.
Turning the Fan speed switch to any of the different speeds doesn’t have any effect.
On the other hand the Temperature control lever seems to be working ok, because according to the position it changes temperature of the (little) air that comes out.
Wouldn’t a dead fuse or relay prevent the fan to work completely, at any speed?
Why is it working so slowly, even with the fan **** at 0?

TIA for your help!

Regards

 

Check that your evaporator is not clogged. Usually there is a lot of debris that collects on the coil and decreases the airflow dramatically.

 

Fan speed 0 is not fan off - it is just the lowest fan speed. (0 was a bad choice - should have started at 1)

The DEF slider position and fan switch to max (4) should activate full fan regardless of the resistor pack - does it?

The buzz could be vacuum related or could be electrical (e.g. most likely a relay).

Swap the blower relay for a known good relay also swap the X-Relay and DEF relay.

Alan

 

were is the evaporator location for AC on 82 U.S.

 

Thanks Alan,
So, if Fan speed 0 is not Fan Off but it's the lower speed, than in that position it is working ok.
The problem is that there is absolutely no change if I move the slider to DEF or any other position or the switch to position 3, 4, whatever!
It seems it only works at the slowest speed!

Regards

 

See the thread below about cleaning the evaporator.
https://rennlist.com/forums/928-foru...-cleaning.html