The fan will run and blow warm air but only in FAN or FAN ON mode – delivering heat – but NOT in AUTO mode. This is a bad temperature sensor in the unit; replace the fan limit controller.

Why does my furnace not work in auto mode?

Solution: Switch the thermostat setting to “Fan Auto.” Turn off the power, then check to make sure there isn’t a short in the wiring. Also make sure that the wires for the thermostat and furnace/air conditioner aren’t touching together.

Should furnace fan be on auto or on?

“auto” is the best setting for your furnace fan in the winter. It will aid in saving energy and money while also working to keep your home at an optimal temperature. However, for summer, “on” is the best setting for your furnace fan.

How do you reset a furnace blower?

Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious as the housing may be hot. If the button is popped up, press it down.

What device turns on a blower motor during the heating mode?

The high limit switch is also an extremely important safety device inside your furnace. When the furnace begins running, the switch’s role is to turn on the blower fan when the supply air gets hot enough.

Should I set my thermostat to auto or circulate?

If you want to keep the energy bills low, you should set the thermostat to ‘Auto’. However, if you prefer more even distribution of heat inside the house, it’s better that you set the thermostat setting to ‘On’.

Should you leave your furnace fan on all the time?

Better Indoor Air Quality

Whenever the fan is on, air is going through the furnace filter. Leave it on continuously and you’re likely to see less dust around. It’s also important to have a good filter. The many types of HVAC filters can help reduce allergies, VOCs, as well as bacteria and viruses.

How do you reset a fan limit switch?

Quote from the video:
Quote from Youtube video: Control normally will not reset itself so in the case where that limit is open it has a manual reset on it basically you have to push the little button down on top of the on top of the limit control.

How do I know if my limit switch is bad?

The most common sign of a malfunctioning limit switch is the continuous operation of your furnace’s blower. Just as the limit switch won’t allow the fan to turn on until the warm air has reached the right temperature, the limit switch also shuts down when the air cools to a certain temperature.

Where is the furnace fan limit switch located?

Your fan limit switch is located inside the furnace panel cover, usually near the upper right corner. The fan limit switch is responsible for turning the blower on and off at the appropriate times.

What does a furnace limit switch look like?

Quote from the video:
Quote from Youtube video: The limit switch monitors the temperature of the air passing over the heat exchanger.

What controls the fan on a furnace?

A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. Essentially, this means that it determines when the hot air should be blown through your ventilation system. The fan limit switch also has two other functions.

How do you test a blower motor switch?

Test the switch. Plug the connector back in to the blower motor, and then trace the wire harness back to the connector closest to the blower motor switch, usually located under the dash. Disconnect the connector and set the multimeter to ohms.

How do I know if my blower motor switch is bad?

  1. Switch only works on certain settings. One of the first symptoms commonly associated with a bad or failing blower motor switch is a switch that only works on certain settings. …
  2. Switch is stuck. Another symptom of a bad or failing blower motor switch is a switch that is stuck, or frequently gets stuck. …
  3. Broken knob.
  4. How can I tell if my blower motor resistor is bad?

    Here are some of the warning signs of a bad heater blower motor resistor:

    1. Fan does not work at all, so no air comes out of the vents.
    2. Fan only works on some speeds and not others.
    3. Fan only works on the highest speed.
    4. Fan runs all the time and can’t be controlled with the fan switch.
    5. You see smoke coming out of the vents.

    How do you know if your blower motor relay is bad?

    If you have a faulty blower motor, you may experience low airflow from the vents, even when the fan is on high. There will be no air coming from the vents if your fan isn’t working due to a bad blower motor resistor. Blown relay circuit fuses or melted relays are more serious signs of a bad blower motor relay.

    How much does it cost to replace a blower motor relay?

    between $73 and $83

    The average cost for blower motor relay replacement is between $73 and $83. Labor costs are estimated between $36 and $46 while parts are priced at $37. This range does not include taxes and fees, and does not factor in your specific vehicle or unique location. Related repairs may also be needed.

    Where is the blower motor relay located?

    The blower relay is located near the front of the fuse block and is labeled “Blower.” Inspect the center of the relay. If the metal rod inside is broken, the relay will need to be replaced.