Why does my blower keep turning on and off?

If your blower is constantly turning on/off when the furnace isn’t heating… …you most likely have a bad fan limit switch. Your furnace fan limit switch is basically a control system that determines when the furnace blower assembly should turn on and off.

What can cause the blower to come back on for a short time after cycling off?

Usually this is a problem of residual heat in the furnace heat exchanger rising into and re-heating the plenum air, causing the fan limit switch to turn the fan back on to try to cool down the system by extending the heat exchanger temperature purge cycle time.

Why does my blower motor work sometimes?

When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds so the fan runs slower.

How do I reset my blower fan?

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).

Can a thermostat cause short cycling?

Your thermostat could also cause the HVAC system to cycle on and off rapidly, a process known as short cycling. Your furnace or central air conditioner spends a good amount of energy simply turning on and off, which is why you want yours to run for at least 15 minutes at a time before shutting off.

Why does my furnace turn off after 15 minutes?

If your air filter is too dirty, it will restrict airflow. Your furnace will then shut off prematurely to avoid overheating. We recommend replacing flat filters once a month, and pleated filters every three months. It’s easy to stay on top of changing your filter by adding a Filter Reminder on your thermostat.

Why does my furnace turn on and off every few seconds?

So, if your furnace keeps turning off and on too quickly, your thermostat might be malfunctioning or broken. There are several things that could be causing your thermostat to not work properly. The wiring could be old and need replacing, it might need new batteries, or it could be the location of your thermostat.

Why is my furnace blower short cycling?

Clogged Air Filter

One of the most common causes of short cycling is restricted air flow. You’ve probably already checked your filter and changed it if it was dirty. But if not, now is the time to do it. When the filter is filthy, fresh air cannot get into the furnace, causing it to overheat and shut down.

Why does my furnace turn on every 10 minutes?

Bad Thermostat: If your thermostat has a problem, it can cause your furnace to run cycles that are either too long or too short. If the thermostat is sensing the incorrect temperature and not sending a cut-off signal soon enough, or if the battery is dying, your thermostat can cause your furnace to run erratically.

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.

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 test an indoor fan motor?

Quote from the video:
Quote from Youtube video: And then you put one probe on there and one to the l2. Common neutral bar right here and you should read 120 volts. If you read 120 volts. And your blower motor is not turning on then.

How do you fix short cycling?

How To Stop and Prevent Short-Cycling

  1. Check your air filter. Believe it or not, a clogged air filter can cause a wide variety of air conditioning issues. …
  2. Check your thermostat placement. …
  3. Check your air conditioner’s refrigerant levels. …
  4. Replace the low-pressure control switch. …
  5. Check the compressor.

How do I fix my short cycling nest?

To fix this problem, you have to replace or redo the wiring that connects your Nest thermostat to the HVAC equipment. You may also need to replace the C-Wire. Fitting a common wire and adapter on your Nest thermostat will keep the battery level up for several months.

What causes short cycling?

Frozen evaporator coils are a common cause of short cycling. Sometimes, air conditioners freeze up when they’re running while it’s too cold outside, usually at night. In other cases, freezing may be caused by a dirty filter or a mechanical problem. Shut your system down, allow it to thaw completely, then run it again.

Can too much refrigerant cause short cycling?

The most common indicators of an overcharged system are:

Condenser flooded with liquid refrigerant, which will reduce its capacity; besides causing excessive subcooling at the condenser outlet, this condition may cause the compressor to short cycle on high pressure cut-out; A compressor that sounds louder than usual.

Is short cycling normal?

One of the most common, and unfortunately harmful, problems an air conditioner can have is something called short-cycling. This is both a symptom of a problem and a cause of a problem. Sometimes a few simple adjustments may be all that’s needed to repair the issue.

What is considered short cycling?

Short cycling has nothing to do with time between normal on-off cycles. Short cycle occurs when unit is rapidly turned off then back on within less than 3 minutes at t-stat or power interruptions such as during lightning storms.

How do you fix a short cycle on a furnace?

A dirty air filter is the most common cause of short-cycling. If your air filter is clogged with dirt, it won’t allow proper air flow to the heat exchanger. That can cause the furnace to overheat and forces the high limit switch to ride to the rescue by shutting the furnace off.

How often is short cycling?

“Short cycling” means switching on and off every 30 seconds or less.