AC Not Heating

Quick answer

Check the thermostat settings and air filter first. If both are correct, turn off the power and inspect the emergency heat setting or heat pump. If the issue persists, a professional inspection may be needed.

Confirm the symptom

• The AC is running but not producing warm air
• The thermostat shows heating mode but no heat output
• The system blows cold air instead of warm air
• The heating function worked before but now doesn't

Tools and prep

• Thermostat manual
• Screwdriver
• Vacuum cleaner with brush attachment
• Flashlight
• Safety gloves
• Turn off power at the circuit breaker before inspecting electrical components

Step-by-step troubleshooting

1. Check Thermostat Settings
   Do: Verify the thermostat is set to 'Heat' and the temperature is higher than the room temperature.
   Observe: Thermostat is in correct mode and temperature setting.
   Means: Thermostat settings are correct.
   Next: Proceed to step 2.
2. Inspect Air Filter
   Do: Remove and examine the air filter for dirt or blockage.
   Observe: Air filter is clean or dirty.
   Means: A dirty filter restricts airflow and heating efficiency.
   Next: Replace or clean the filter if dirty, then test the system.
3. Check Emergency Heat Setting
   Do: If your system has an emergency heat setting, ensure it's turned on.
   Observe: Emergency heat is activated or not.
   Means: Emergency heat may be required if the heat pump is malfunctioning.
   Next: If emergency heat is on and there's still no heat, proceed to step 4.
4. Inspect Heat Pump
   Do: Check the heat pump for visible damage or frost buildup.
   Observe: Heat pump appears normal or shows signs of malfunction.
   Means: A faulty heat pump may prevent proper heating.
   Next: If the heat pump is damaged, contact a professional.
5. Check for Error Codes
   Do: Look at the thermostat or indoor unit for any error codes or blinking lights.
   Observe: Error codes or blinking lights present or not.
   Means: Error codes can indicate specific issues with the heating system.
   Next: Refer to the unit's manual to interpret the error codes.
6. Test Blower Motor
   Do: Listen for unusual noises from the blower motor and check if it's running.
   Observe: Blower motor runs quietly or makes strange noises.
   Means: A malfunctioning blower motor can prevent proper heat distribution.
   Next: If the motor is faulty, contact a professional for repair or replacement.
7. Inspect Ductwork
   Do: Check the ducts for leaks, disconnections, or blockages.
   Observe: Ducts are intact and free of obstructions.
   Means: Leaky or blocked ducts reduce heating efficiency.
   Next: Seal or repair any leaks and ensure ducts are clear.
8. Check Circuit Breaker
   Do: Verify the circuit breaker for the AC system hasn't tripped.
   Observe: Circuit breaker is in the 'On' position.
   Means: A tripped breaker could cut power to the heating components.
   Next: Reset the breaker if tripped and test the system.

Common causes

Parts matching

Common parts needed for an AC not heating issue include:

• Air filter
• Thermostat
• Heat pump
• Blower motor
• Duct repair materials

Purchase parts that match your AC system's make and model for compatibility.

When to call a professional

• The system still doesn't heat after checking all settings and filters
• There are visible signs of damage to the heat pump or blower motor
• Error codes persist and cannot be resolved with basic troubleshooting
• The system makes loud or unusual noises when attempting to heat
• You smell gas or notice a burning odor coming from the unit
• The circuit breaker continues to trip after being reset

FAQ

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