heater motor

[tas911]

Hi I have a 1972 911 and my heater motor only works on the first two speeds. Does this mean the motor is on the way out or is there something that I can do


Thanks


Tas

[Elu]

Check the high contact and wiring. Motor works off of voltage change, if the first two are working then the motor should be fine.

[tas911]

Thanks ELU, Are you suggesting to check the wiring on the motor or at the controls..not sure I understand.


Thanks

Tas

[Elu]

Well I would check both sides. Start at the motor side. Use a volt meter and check to see if there is voltage on the high side. Probably somewhere near 12V coming on the high speed wire. You'll need to get a wiring diagram to see which wire colors are for the different speeds. It will be very similar to the fresh air fan connection in the front cowling. If there is no voltage, your wiring may be cut or loose at the controls side. You'll have to trace it at that point. Sometimes the contacts break or the metal contactors wear down. However, it seems like it should be a repair job and not a replacement.

[tas911]

Thanks, I'll give it a go tonight.

Tas

[Elu]

I may be stating the obvious, however, make sure that when you check the high speed wiring you have the fan controls engaged for high speed and the fan turned on so that there is voltage in the system.

[Rot 911]

Tas you say "heater motor" on a '72 you only have a blower for the fresh air. The heat is all pushed forward by the engine fan.

[Elu]

Good point Kurt...although nothing surprises me anymore with the older ones. I have a 74 without a heater motor...I suppose that is unusual as well, mine too is pushed by the engine fan....I thought that 73 was the first year for the heater blower. but there are so many after market fixes and mods, you just never know.