Furnace Relay Switch Problem

If the fan limit switch worked normally continue as follows.

Furnace relay switch problem.

If this isn t the problem you can reset the power by switching the furnace off at the furnace power switch for about a minute. You may have to check a few areas to eliminate this as a problem. That is definitely one possibility. Then turn the ac back on to test it.

Check the emergency switch usually located near the furnace room. Turn off the furnace at. But another problem that occurs just as frequently from a faulty relay is that the heating elements and the blower fan will refuse to shut off. Set the building thermostat to call for heat.

Furnace blower fan wont turn off fan select switch on the thermostat is in the manual on position a control wiring problem where the insulation on the wiring is worn off a bad relay fan sequencer relay fan limit control or circuit board with contacts sticking this depends on the type. Move the thermostat mode switch from cooling to off and move the fan switch from auto to on let the blower run for at least 30 minutes or until there s good airflow at the registers. Check the main circuit breaker entrance panels and any fuses or circuits found in the furnace itself. The reason for this is that the relay could become welded into the closed position and continues to allow power through to the heating elements and the fans.

Switch it back on and see if this corrects the problem. Move the lever on. A switch inside the door compartment engages when the door is closed properly. Turn off electrical power to the heating system reconnect the fan motor where you previously disconnected it turn on electrical power to the heating system call for heat.

With the furnace on use a. If it works for the next 12 hours you ve solved the problem. Furnaces require electricity to operate oil pumps thermostats internal electrodes relays and other electrical components. Verify the furnace door is closed fully as an open door will cause the furnace not to work.