Fan Limit Switch Troubleshooting

If the fan in your furnace runs continuously or turns off and on too frequently you may need to adjust or replace the limit switch.

Fan limit switch troubleshooting.

Step 1 remove the top access panel on the front of the rheem furnace. Pull the white button out to put the fan back into auto mode turning on and off under control of the switch and. Push the white button in to force the fan to on or manual or always running mode. The furnace filter is clogged and raises the temperature within the plenum prematurely tripping the sensor.

This opens the safety circuit and prevents the furnace from heating. Fan limit switch troubleshooting list before you get started check the air filters in the system. Where can you buy a fan limit switch. High limit 200 degrees fahrenheit.

And the limit switch should be pulled out. Problems that commonly occur with fan limit switches include. However the typical temperature settings are as follows. Fan limit switches can be bought at an hvac supply stores or online.

Finding the limit switch in a rheem furnace takes just seconds. If not shut the power off at the breaker panel. Open the access panel and locate the high limit switch. Set the building thermostat to call for heat.

The switch s sensor becomes dirty and stops working correctly. Some control guides call this summer. If there is a serviceman switch turn it off. To test a limit switch you ll want to check continuity to determine what state the switch is in.

The instructions differ depending on whether you have a combination switch or separate high and fan control limit switches as well as on the specific model you have. If both the blower motor and limit switch test good than other possible problems may be the contactors circuit board or gas valve and possibly the thermostat. The blower motor stops working and overheats. Dirty clogged air filters can cause high limit switches to open.