Why will a blower run on the on position and not on AUTO?

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.

Should fan be on AUTO or on for cooling?

Keeping your fan on AUTO is the most energy-efficient option. The fan only runs when the system is on and not continuously. There is better dehumidification in your home during the summer months. When your fan is set to AUTO, moisture from cold cooling coils can drip and be drained outside.

What would cause my AC to only run when the fan is turned on and not on AUTO?

If the fan is the only thing running when the AC unit isn’t, there may be a faulty relay switch prohibiting the settings on the thermostat from being communicated to the fan. Another cause could be a wiring issue or a short circuit preventing the system from recognizing the on and off signals.

Why is my thermostat not working on AUTO?

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. Check your thermostat’s batteries.

Where is the blower motor reset button?

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.

How do you test a fan limit switch?

Quote from the video:
Quote from Youtube video: To test the component. You can disconnect the wires. And check the resistance value across the contacts to see if it's open right now this switch is closed. And we read 0.0 ohms of resistance.

What is the difference between fan on and fan Auto?

The blower fan pulls warm air into the AC to be cooled, then blows the cool air back into your home. When you select the: AUTO setting, it means the fan will only turn on when your system is cooling air. ON setting, the fan will run non-stop—even if your AC isn’t actively cooling your home’s air.

Is it OK to run the air conditioner fan continuously?

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.

What is the difference between auto and fan on my air conditioner?

The fan setting controls your AC’s blower; A fan inside your system that helps distribute air throughout your home. AUTO means the fan turns on “automatically” ONLY when your system is heating or cooling your air.

Can I run the fan only on thermostat?

You can run your system’s fan independently of heating or cooling. So your system doesn’t need to be actively heating or cooling to run the fan. However, you can only run the fan when your thermostat is set to a temperature mode (like Cool mode, for example).

How do you manually reset a thermostat?

Reset the Thermostat

Common methods for resetting a thermostat include installing the battery backward for five seconds, pushing a recessed reset button with a pin or paper clip, or shutting off the breaker to the thermostat for 30 seconds.

How do you tell if you need a new thermostat in your house?

Signs You Need a New Thermostat

  1. Heating or cooling system will not turn off or on.
  2. The temperature reading is incorrect.
  3. Recent spike in your energy bill.
  4. Frequent temperature fluctuations.
  5. Thermostat is 10 years old or older.

Why is furnace fan running non stop?

If your furnace fan won’t turn off, you most likely have one of these 3 problems: Your furnace fan limit switch is set to “manual override” The fan limit switch is faulty and needs to be replaced. There’s a problem in your thermostat wiring.

How many times can I hit the reset button on my furnace?


Don’t hit “reset” more than twice. The process pumps oil into the burner chamber, where it can accumulate if you have no ignition. Then when the furnace finally does start, it can do so explosively. So if the button won’t reset, or quickly pops up again, it’s time to call a professional repair service.

How do you reset a blower motor switch?

How to Find and Reset your Furnace Motor Blower

  1. Step 1: Turn off the power to the furnace. …
  2. Step 2: Remove the blower compartment cover. …
  3. Step 3: Make sure the blower is completely cooled off. …
  4. Step 4: Locate the reset button. …
  5. Step 5: Press the button in (assuming that this is your issue and that the button has popped).

Where is the fan limit switch located?

Quote from the video:
Quote from Youtube video: Right behind the electrical gas valve. And it's located in the heat exchanger area.

How do you reset an air conditioner fan?

How to Reset an Air Conditioner

  1. Power down your AC. Start at your circuit breaker panel and flip the breaker that powers your AC. …
  2. Find the button. Most air conditioning units are equipped with a reset button. …
  3. Hold down the reset button for 3 to 5 seconds and then release.
  4. Restore power to your AC.

How do you test a blower motor capacitor?

Quote from the video:
Quote from Youtube video: Use a multimeter with the capacitance testing function now touch the probes to each terminal if the capacitor is good then the multimeter will show a reading very close to the rated.

How do I know if my capacitor or fan motor is bad?

5 Signs Your AC Fan Motor Is Bad

  1. The cooling fans won’t turn on.
  2. The fan turns on when the AC is running, but the blades rotate slowly.
  3. You can hear a rattling noise coming from the condenser unit.
  4. It smells like something’s burning.
  5. Blown fuse.

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

The clearest sign of a problem with a furnace capacitor is when the blower fans stop running. If your furnace comes on, but no air blows through the vents and you don’t hear the noise of the fans, then the trouble is either a burnt-out motor or a damaged capacitor.