Table 2-1. Direct Support Troubleshooting Guide (Continued)
TEST OR INSPECTION
Install a jumper wire across heater terminals 4 and 5. Reconnect P66. Start the heater,
(a) If the heater operates correctly, replace the thermostat (para. 2-69).
Replace the element contactor. Refer to para. 2-69.
Fan motor runs hot (thermal cutout may be opening).
Check for dust accumulation or excessive dirt on motor.
Clean fan motor and casing of grease and oil accumulation.
Check for dirt accumulation in the louvers and heating elements.
Replace motor. Refer to para. 2-69.
Thermostat calls for heat but heater does not function (see Figure 2-1 for heater circuits).
Check if the thermal cutout is open. This will de-energize the heater elements and the control circuit. It typically will
happen if there was a power cutoff during heater operation which does not allow the fan to purge heat residual after a
normal shutdown of the heater. Allow heater to cool down. The cutout should reset.
If it does not reset, replace the thermal cutout (para. 2-69).
Figure 2-1. Electric Heater Wiring Diagram
Fan motor does not operate (see Figure 2-1 for heater circuits).
Electrical high voltage can cause serious injury or death. Some tests performed in
troubleshooting require power to be connected. Always take proper measures to ensure
Check for 208-220 VAC across contactor terminals L1 to T3 (REF: Interconnection diagram FO-2, Sheet 10) when the
fan should be operating.
If voltage is present, replace the motor (para. 2-69).
(b) If voltage is not present, replace the contactor (para. 2-69).