What would cause a furnace blower not to kick on?

If you see or hear the fan turn on, your blower motor is not the culprit. If the fan does not start, you have a wiring issue (circuit breaker trips) or motor problem (circuit breaker does not trip). While your thermostat may be at fault, only an HVAC technician can diagnose and remedy the issue correctly.

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.

How do I reset my blower motor?

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).


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.

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.

Why is my blower fan not working?

If little air is coming through the vents (hot or cold), then it could be because the blower motor for the fan or a switch or resistor that controls fan speed isn’t working. Another cause might be that the electronically controlled “blend doors” that direct air flow are stuck or broken.

Should outside fan run when AC is on?

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. If your fan runs continuously, moisture does not have a chance to drip outside.

How much does a fan capacitor cost?

Blower Capacitor Replacement Cost



The price for a new blower capacitor is typically between $9 and $12. This provides the necessary power to spin the blower motor so the fan moves in the furnace.

How do you troubleshoot a blower motor?



Quote from the video:
Quote from Youtube video: Just turn the blower wheel with your hand and see if it spins freely if there's any resistance or rubbing or grinding that would verify that the blower is in fact seized.

How do you test a blower motor module?

Quote from the video:
Quote from Youtube video: Check for short to ground use an ohm meter to measure the resistance from all three of the motor connector pins to the aluminum end plate of the motor.

How do you test a fan limit switch?

Quote from the video:
Quote from Youtube video: Go straight to your limit leave the limit then you go to your thermostat. That. Way if this mechanism failed you would shut off probably thermostat won't allow anything to come on.

How do you bypass a thermostat on a fan?



Quote from the video:
Quote from Youtube video: Ones your jump ring stick this jumper in there and tighten those screws back up and flip the furnace which Bagon. Well guys and that is how you bypass your thermostat.

How do I reset my thermostat?

Here are the step-by-step reset instructions:

  1. Turn your thermostat off by switching it to the off position.
  2. Find the breaker that powers your HVAC system and turn it off.
  3. Wait 30 seconds and turn the breaker back on.
  4. Turn your thermostat back on.


How can I test my thermostat?

Quote from the video:
Quote from Youtube video: And then we would go ahead and turn her power back on and see if our Heat turns on you may have your blower motor turn on for about 30 seconds in order to cool off the heat exchanger.

What is bypass thermostat?



In order to do this manufacturers have redesigned their engines to utilise what is called a reverse poppet or bypass style thermostat. This style of thermostat has two valves instead of the one valve that is seen on a non-bypass thermostat.

How do you check thermostat wires?

Quote from the video:
Quote from Youtube video: The R and the G inside the thermostat to turn the fan on now I'm going to go ahead and turn the fan off and you see that our voltage has decreased. So what we're looking at is reading 24 volts.

Which wire is which thermostat?

Thermostat Wiring Tips



If your thermostat controls your heat, you will have a white wire. The Y wire is yellow and connects to your air conditioning compressor. The G wire is green and connects to the fan. Rc and Rh: The red wire(s) are the power source for your thermostat.

How can I run my furnace without a thermostat?

Quote from the video:
Quote from Youtube video: Start. Here that combustion blower starts so that means the furnace is beginning to start I'm gonna stop it. Now in order to run the air conditioning. You actually have to cross the R.

How do I know if my furnace thermostat is bad?



7 Ways to Tell Your Thermostat Is Broken

  1. Thermostat Has No Power. …
  2. AC or Furnace Won’t Turn On. …
  3. Heater or AC Won’t Turn Off. …
  4. Thermostat Doesn’t Match Room Temperature. …
  5. Thermostat Doesn’t Respond. …
  6. Short Cycling. …
  7. Thermostat Forgets Programmed Settings. …
  8. Thermostat Replacement Services.


Can thermostat cause furnace not work?

One of the most common furnace problems is a malfunctioning thermostat. A sure sign your thermostat isn’t working properly is if your fan is constantly running. This will cause your thermostat battery to run, and cause your furnace to work inefficiently.