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Furnace not heating
Brand:Comfortmaker
Model:RCC-COMFORTMAKER-FURNACE
Product:Furnace
Featured Video
Furnace Not Heating? Gas Furnace Troubleshooting
03:52
Common solutions for: Furnace not heating
01 - Igniter
The igniter gets very hot and glows bright orange to light the gas burner. If the igniter fails or cracks, the furnace won’t heat. To determine if the igniter is faulty, remove the igniter and inspect it for cracks. If the igniter is cracked, replace it. If the igniter is not cracked, use a multimeter to test the igniter for continuity. If the igniter does not have continuity, replace it.
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Top Solution
02 - Gas Supply Problem
Check the gas control valve to ensure that it is turned on and there is gas present at the valve. Natural gas pressure should be close to 4 inches water column at the furnace input; propane pressure close to 11 inches water column at the furnace input. The gas pressure can be checked with a manometer at the valve.
Top Solution
03 - Incoming Power Problem
Check to see if there is power to the furnace. One or more indicator lights on the control board should be illuminated. If there is no power to the furnace, check the home's furnace circuit breaker or fuse. Confirm the power switch on the side of the furnace is turned on.
Top Solution
04 - Check Fault Codes
If the furnace stops working properly the control board will often display a fault code to help diagnose the problem. The fault codes are displayed by a flashing light or multiple lights on the control board. Each sequence of flashes followed by a pause will indicate either an error code or the status of the furnace. Some manufacturers will use red and green lights to indicate specific fault codes. Fault codes are often displayed on the access cover of the furnace for easy reference.
Highly Likely
05 - Improper Vacuum or Pressure
The draft inducer fan motor assembly creates a vacuum when running which closes the pressure switch. Check the pressure hose and port on the inducer assembly for leaks or obstructions. A clogged condensate trap or drain, or restricted heat exchanger, can also cause a pressure switch to not function. Replace the pressure switch if there is proper vacuum or pressure but the switch is not working properly. You can test the pressure switch for electrical continuity with a multimeter. The contacts wi...ll either close or open depending on the application.
Highly Likely
06 - Draft Inducer Motor
The draft inducer motor draws air into the heat exchanger and then exhausts it out the flue. The pressure switch senses a pressure change and closes a switch to signal the control board that the furnace has proper air flow. If the draft inducer motor is defective, it may be unable to close the pressure switch, causing the ignition process to stall and the furnace to shut off after a few minutes. If the ignition process stalls, the furnace will shut off. If the draft inducer motor is at fault, r...eplace it.
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Common
07 - Wall Thermostat Batteries
Most wall thermostats are either powered by an enclosed battery or by the furnace transformer. If the thermostat display is dead, you can remove the thermostat cover and look for replaceable batteries. Replace the batteries if needed and check operation.
Common
08 - Control Board
The control board regulates the power supply to all of the components of the furnace. If the control board fails, it might not send voltage to the ignition system, causing the furnace not to heat.
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Common
09 - Relay
The relay is an electromechanical switch used to control components in the furnace. If the relay fails certain components may not receive power and will fail to operate.
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Common
10 - Flame Rollout Limit Switch
The flame rollout switch monitors the heat surrounding the burners. If the inducer fan motor cannot draw enough air through the burners, or if the furnace is not venting properly, the rollout switch will open to halt the ignition sequence and prevent the furnace from heating. To determine if the flame rollout switch is defective, use a multimeter to test it for continuity.If the switch does not have continuity and the reset button is not tripped replace it. Be aware that poor airflow through the... burner is often a result of insufficient ventilation or a restricted exhaust vent. Make sure that your furnace is in a properly ventilated location and the exhaust vent is clear of obstructions.
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Common
11 - Clogged Draft Inducer Blower Wheel
The draft inducer motor draws air into the heat exchanger and then exhausts it out the flue. The pressure switch senses a pressure change and closes a switch to signal the control board that the furnace has proper air flow. If the draft inducer blower wheel gets clogged, it may be unable to close the pressure switch, causing the ignition process to stall and the furnace to shut off after a few minutes. If the ignition process stalls, the furnace will shut off. If the draft inducer blower wheel i...s clogged you can try cleaning it. If the blower wheel is damaged, the wheel or the inducer assembly may need to be replaced.
Common
12 - Run Capacitor
If the run capacitor is defective, the fan motor might be noisy, overheat, or not run at all. To determine if the run capacitor has failed, inspect the capacitor. If the run capacitor is bulging or leaking, replace it.
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Less Common
13 - Capacitor
If the capacitor is defective, the fan motor might be noisy, overheat, or not run at all. To determine if the capacitor has failed, inspect the capacitor. If the capacitor is bulging or leaking, replace it.
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Less Common
14 - Pilot
A pilot in a furnace is a small flame that is used to light the main burners when the thermostat calls for heat. The pilot can be lit manually or be lit automatically by a spark igniter or a small hot surface igniter. A thermocouple or sensor is used to confirm the pilot is lit before gas is allowed to enter the main burner. If the pilot is damaged or the flame is too weak to stay lit, the pilot will need to be replaced.
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Less Common
15 - Tripped Circuit Breaker
If the circuit breaker has tripped, you can try resetting it and see if the furnace will run. If the circuit breaker keeps tripping or it won't reset, the circuit breaker itself may be bad or there may be a shorted component in the system. Do not keep trying to reset the breaker if it won't reset as this can cause further damage to the system. A service technician may be required if this attempt to reset the breaker does not work.
Less Common
16 - Gas Valve Assembly
The gas valve opens to allow gas to flow into the burner. If the gas valve is defective, the valve will not open, preventing the furnace from heating. To determine if the gas valve is at fault, use a multimeter to test it for continuity. If the gas valve does not have continuity, replace it.
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Less Common
17 - Pressure Switch
The pressure switch closes when the burner has sufficient airflow. If the pressure switch isn’t working, it might not close when the proper airflow is present, causing the ignition process to stall. To determine if the pressure switch is defective, use a multimeter to test the switch for continuity. If the pressure switch does not have continuity, replace it.
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Less Common
18 - Hose
The draft inducer motor assembly draws air into the heat exchanger and then exhausts it out the flue. The pressure switch senses a pressure change and closes a switch to signal the control board that the furnace has proper air flow. If the hose between the draft inducer motor and pressure switch is torn or otherwise damaged, the pressure switch may be unable to close, causing the ignition process to stall and the furnace to shut off after a few minutes. If the air hose has any cracks or holes in... it, replace the hose.
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Less Common
19 - Wire Harness
A wire harness, a group of wires with the required connectors and plugs, is used to control and monitor various furnace components. If a wire harness is damaged, one or more of the components may not run or may only run intermittently. A damaged wire harness will need to be replaced.
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Less Common
20 - Air Flow Problem
The furnace must have proper airflow through the burner in order to run properly. The furnace draws air from the surrounding area or through tubing from outside the home or building. If the furnace is located in a utility closet or in a cramped storage room, there may not be sufficient available air for the furnace to heat properly. If the furnace draws air from outside a home or building, check for obstructions at the air inlet and exhaust outlet pipes.
Uncommon But Possible
21 - Power Switch Turned Off
There is usually a power switch on the side of the furnace. The switch may have been inadvertently moved to the off position. Turn the switch to the "On" position and confirm the system is working properly.
Uncommon But Possible
22 - Blower Wheel and Housing
The spinning blower wheel will circulate the heated air throughout the home's venting. If something is obstructing the blower wheel and preventing it from turning, the air won't be circulated. Inspect the blower wheel and housing for any obstructions and confirm the wheel is properly seated on the motor shaft and can rotate freely.
Uncommon But Possible
23 - Control Module
The control module regulates the power supply to all of the components of the furnace. If the control module fails, it might not send voltage to the ignition system, causing the furnace not to heat.
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Uncommon But Possible
24 - Blower Motor
The blower motor spins a blower wheel to circulate the heated air throughout the home's venting. If the motor is burned out, the air will not be circulated. You should try turning the blower wheel by hand to determine if it can rotate freely. If blower wheel does not turn freely, it's likely the blower motor bearings have seized and the motor will need to be replaced. You can also use a multimeter to determine if voltage is reaching the motor. If power is getting to the component, but the motor ...doesn't run, it is likely defective.
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Uncommon But Possible
25 - Transformer
A furnace transformer is the component that decreases or increases the incoming voltage to power the unit. A faulty transformer can prevent the furnace from heating. If there is no secondary 24 volt power to the thermostat, the furnace trips a circuit breaker when it comes on, or you hear a consistent humming or vibrating noise, it's possible the transformer has failed.
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Uncommon But Possible
26 - Limit Switch
The flame rollout or limit switch monitors the heat surrounding the burners. If the inducer fan motor cannot draw enough air through the burners, or if the furnace is not venting properly, the rollout limit switch will open to halt the ignition sequence and prevent the furnace from heating. To determine if the flame rollout limit switch is defective, use a multimeter to test it for continuity. If the switch does not have continuity and the reset button is not tripped replace it. Be aware that po...or airflow through the burner is often a result of insufficient ventilation or a restricted exhaust vent. Make sure that your furnace is in a properly ventilated location and the exhaust vent is clear of obstructions.
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Uncommon But Possible