850 turbo wagon. Automatic climate control. The AC and heat work fine, but the volume of air coming out of the vents seems quite low. When the fan speed adjustment switch is used, the fan goes from slow to fast as it should, but never seems to put as much air as it should. Could this be a problem with the switch or the resistor?
Thanks.

 

can you hear the blower speed up when going to high or does it go up a little but not all the way? Does it seem to be missing only the top speed? Could be a few things - the blower cage could be binding and needs replacement, if missing top speed could be a fuse or resistor. Resistors are pretty straight forward to replace - you can access via the glove box (pull out the rear of the glove box and you'd find the resistor in there...) Top speed on the blower has a separate fuse from the 1-3 speeds so check that first.

 

Thanks for your help. I will look at these things as soon as possible (it's my son's car). Are there two separate fuses in the fuse box under the hood for speeds 1-3 and 4 as well as the resistor behind the glove box?

 

The ACC resistor is ver pricey and to date I dont know of anyone who has successfully repaired one.

Have you looked into the intake of the system. I dont know what year you have but later models came with a cabin filter. The filter could easily be clogged and restricting the air flow. To test this just put the system on Recirc so the air is being drawn from inside the car. If you have done this but it didnt change make sure you have not lost the vent motor behind the glove box. Those motors gears strip or the arm pops off and it will stay in outside vent mode...thus sucking air through the cabin filter.

My guess at this point is if your fan runs and changes speed then its not the ACC resistor, they just die.

1. vent/flaps stuck and not changing to vent
2. Recirc motor or arm failure
3. plugged cabin filter
4. You dont have a cabin filter and have filled the squirl cage up with debris.

 

Thanks for your suggestions. My car does not have a cabin filter. It has a plastic insert that fits inside the air inlet above the fan. It has a rubber top which forms a seal with the overlying plastic cover at the rear of the engine compartment. When I had the cover off and the fan running, the fan is fast and quiet; there is no binding and no debris in the cage. The recirculation flap does not work on its own (it is always in the fresh air position) but it will slowly close if I pull on it with the recirc switch on. The fan speed does not change with the flap closed. I checked fuse #5 (the high-speed fan fuse) and it is good. One thing I have found is that most of the air comes out the central and side vents and there is very little coming out the defrost vents and floor vents even with the selector switch in those positions. If these regulator motors or gears are not working correctly, could that cause the overall decreased air flow?