How to Fix Car Heater
Learn how to fix car heater with our detailed step-by-step guide. Follow our easy instructions to get it done right.
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0 of 6 steps completedStep-by-Step Instructions
1 Step 1: Identify Heater Problem Type
Step 1: Identify Heater Problem Type
Determine if issue is no heat, insufficient heat, or heater blowing cold air.
2 Step 2: Check Coolant Level
Step 2: Check Coolant Level
Low coolant prevents hot coolant from reaching heater core - top off if low.
Engine Coolant 50/50
Pre-mixed antifreeze for topping off
3 Step 3: Test Heater Core for Flow
Step 3: Test Heater Core for Flow
Feel heater hoses - both should be hot when engine warms up, indicating core flow.
Heater Core Flush Kit
Chemical flush for cleaning clogged heater core
4 Step 4: Check Blend Door Operation
Step 4: Check Blend Door Operation
Test if temperature control changes air temp - if not, blend door actuator may be faulty.
Blend Door Actuator
Replacement actuator motor for temp control
5 Step 5: Verify Blower Motor Function
Step 5: Verify Blower Motor Function
Test if blower works on all speeds - weak airflow indicates bad blower or resistor.
Blower Motor
Replacement heater/AC blower motor
Blower Motor Resistor
Resistor pack for controlling blower speed
6 Step 6: Replace Heater Core if Leaking
Step 6: Replace Heater Core if Leaking
If coolant smell, wet carpet, or foggy windows persist, heater core may need replacement.
Heater Core
Replacement heater core for your vehicle