Check Your Flame Sensor If this becomes dirty or corroded, it can cause short cycling and result in your furnace blower shutting off and on frequently. You can clean the flame sensor yourself with a rag or brush and some rubbing alcohol, but if it doesn't work, you may need to call a professional for help.
This can be caused by a couple of possibilities. It's not that you're blower is out of sync, it is either going bad or if this is an older furnace with a fan-limit switch, it is cooling down the heat exchanger too fast (or the unit is underfired) and the fan switch is turning it off.
This can be caused by a couple of possibilities. It's not that you're blower is out of sync, it is either going bad or if this is an older furnace with a fan-limit switch, it is cooling down the heat exchanger too fast (or the unit is underfired) and the fan switch is turning it off.
The top causes to blame when a furnace kicks on and off are: The air filter needs changed. The thermostat batteries need to be replaced. Blower motor malfunctions.
Check the circuit breaker, thermostat settings, and air filter first as these are common causes of furnace fan failure. Inspect electrical connections, listen for unusual noises, and verify proper airflow through vents during operation.
Inspect the Fan Limit Switch for Damage or Shorts
Limit switches control how often your furnace blower turns on and off. If these become damaged or shorted out due to age or wear, this can cause them to malfunction and lead to cycling issues.
Insufficient airflow or insufficient gas pressure. A defective, malfunctioning ignition board, flame sensor, light switch, thermostat, thermocouple, fan limiter, or draft inducer fan. The drainage line is blocked, resulting in a full condensate pan. Temperatures are so low that the furnace cannot stay lit.
It most commonly occurs when the blower fan motor becomes aged or is overworked. A lack of regular maintenance is generally to blame for blower fan burnout.
There are multiple reasons why your furnace is short cycling. These could include a dirty filter, blocked vent, or malfunctioning flame sensor. You can switch for a clean furnace filter, or have your HVAC technician resolve a more complicated issue.
Restricted airflow
Blocked vents or a clogged air filter may cause your furnace to run and then shut off too early. It's easy to fix these issues on your own. You should change your furnace filter at least once every three months. Follow our guide to do it yourself.
Short cycling is a common sign of a bad flame sensor. The sensor thinks that there isn't a flame, so it shuts off the gas as a safety mechanism. Except, there is a flame and without the gas to supply it, it dies. This is a frustrating problem, but an HVAC technician can fix it.
Problems include dirty filters, broken wires, poor voltage supply and faulty limit switch or capacitor. You can test your limit switch with a multimeter, and clean the blower motor's wire coils. If this doesn't work, you may need to replace your furnace blower motor.
If you suddenly hear loud and strange sounds like squealing or grinding, these are symptoms of a bad furnace motor blower that can signal signs of motor bearing problems or a damaged belt in older belt-driven models. Repairs may be possible or it may be time to replace the blower motor entirely.
Check for Electrical Issues: Inspect the furnace circuit for blown fuses and reset circuit breakers if necessary. Inspect the Air Filter: Examine the air filter for debris and dust buildup and replace it if dirty. Clear Obstructions: Ensure there are no obstructions near the blower wheel that might hinder its rotation.
Your furnace blower fan may repeatedly cycle due to a clogged air filter, a malfunctioning thermostat, inadequate airflow, or issues with the furnace's limit switch. Each of these issues can disrupt the blower's operation.
Failed Thermocouple Symptoms
The first is signs of contamination on the tube, which can include discoloration, cracks, or pinholes. Next, check the wiring for any signs of wear or corrosion like missing insulation or bare wire.
In most newer systems, the button is often directly next to the blower motor, while in older systems, it may be harder to spot as it is sometimes underneath or behind the motor. The reset button is often made of yellow or red plastic and marked with a large “R ” to make it easier to spot.
The blower motor contains a capacitor, a device that stores energy to help the motor turn over with a jolt of extra electricity when it first starts up. If the capacitor goes bad, electricity may not reach the motor or it may not have enough electric to power the motor for its initial spin.
Carrier furnaces typically have a small reset button inside the burner compartment. It may be red or yellow and is usually labeled “Reset.” If you're unsure where to find it, consult your furnace's user manual. Hold the button down for about 10 seconds before releasing it.