Step by step guide on how to fix your heater, this information pertains to most cars, trucks and SUV's.
Difficulty Scale: 4 of 10
Tools and Supplies Needed
Begin with the vehicle on level ground, engine off (cold) in park with the emergency brake set.
Step 1 - A heater cannot operate unless the engine
is full of coolant/antifreeze.
If coolant level
is low check the system for leaks.
Step 2 - The
engine
thermostat control the rate in which the engine heats up. If this unit is stuck
open the engine will stay at a low temperature which created little to no heat for
the heater. Visit -
Thermostat Replacement
Step 3 - The heater control air blend door is controlled
by a electronic/vacuum/cable which can malfunction causing a problem. Check the
door operation by moving the heat control from hot the cold while listening for
moment inside the heater plenum. Please Visit -
Blend Door Actuator
Replacement
Step 4 - this problem happens more than I thought
at first, but after reviewing many posts with the same problem the fix was relatively
simple. With the engine running at full temp jack the front of the car up and let
it run for 2 minutes then go to the rear of the car and do the same thing, this
will burp or purge the air bubbles locked in the heater core and allow the heater
to work again. Step 5 - Inspect heater system vacuum lines especially
to the heater control valve. These
vacuum
leaks can cause the system to not function. If a hissing noise is present under
the dash when the engine is running a vacuum leak exists and must be repaired to
restore the heater functionality.
Step 6 - The heater
control valve prevents the flow of coolant into
the heater core during the
air conditioner
function, occasionally this valve will stick not allowing hot coolant to flow, inspect
the valve for movement while in operation.
Step 7 - Use a vacuum gauge to test various control
tubes which are used to move blend door actuators
Step 8 - The heater core is responsible for converting hot coolant into heated air, if this core becomes
plugged it will not operate correctly. To check for a plugged heater core, start
the vehicle and allow the engine to warm up to normal operating temperature while
turning the heater to its hottest setting. Grasp both
heater hoses,
they both should be hot, if only one is hot, the core could be plugged or the heater
control valve is malfunctioning.
Step 9 - If
no air
is being produced from the vents while the heater is in operation inspect the
blower motor
system. If you have any
heater questions, please visit our forum. If you need
car
repair advice, please ask We hope you enjoyed this guide and video. We are creating a full set of
car repair guides. Please
subscribe to our 2CarPros
YouTube channel and check back often for new videos which are uploaded almost
every day. Watch the Video!
Got Any Questions?