In the bathroom, the vent-fan ceiling heater and light are all on the same hot wire. However, there are only 64 volts across the brian heater--which does not work. However the light and fan works fine.

How do I troubleshoot this problem?

  • Are you using a digital voltmeter? – Harper - Reinstate Monica Nov 22 '17 at 3:18
  • How are you measuring the 64 volts? One probe to one end of heater coil, other probe to other end of heater coil? That’s probably normal and only tells you the coil is neither shorted or open (which is good). You really need to take different measurements to diagnose. – Tyson Nov 22 '17 at 20:30

I suspect that the hi-limit has been cycling because of insufficient air flow. (the blower fan is either plugged with dirt or the bearings in the motor are dry or both) The points on the hi-limit have arked to the point that they won't carry a load anymore. You are just getting a carbon trail voltage reading. Don't try to save this heat-fan-light. Replace it. It is most likely a hazard. If you purchase and install a new unit, make sure that it goes on a 20-Amp dedicated circuit complete with 12-gauge wire. P.

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