Speed controler? Cold air blower

[Guest]

Hi ya,

Hoping someone can help. - 911 - 1989 Carrera sport.

I have just had the Cold Air motor replaced only to find it work at one (full on ) speed. The garage believes I need to change the Bi Metalic Thermo switch but this sounds like a safety cut off to me. Does anyone agree or do you know what needs to be changed to get the various speeds once again.

Thanks

AP

 

[nathan 1981 930 G50]

I don't know the answer to your question, sorry.

I would like to know though and I doubt it will be what you have been told.

Please let us all know when you find out.

 

[Geoff_Fields]

I think that the first two speeds are achieved by dropper resisters in series with the supply from the switch. These resistors have thermal protection by use of a bi-matalic switch. So the fault could indeed be the overload device or the resistors are burnt out (open circuit) or possibly the speed selector switch is at fault.

 

[richthomas]

Geoff is exactly right and would be my first look. The swith is however inside the main fan housing in the front compartment, so if it has been apart to change the motor it will need to all come out again to change, or clean the switch.

The latter would probably sort it out, run some stiff paper or thin card over the contacts which may be slightly corroded. This will clean the metal without damaging it.

I am surprised that if you have had the motor changed they didn't check or clean the switch before re-fitting it. You can connect the fan and check it runs on each speed with out fully fitting it all back together.