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Troubleshooting
/ Car Heater
Failure
Car Heater Does Not Work
Your car's heater is a life saver in cold weather. The heater core in your car is similar to the
radiator in the front of your car,
in fact it looks like a small radiator. The difference is the heater is mounted
inside the car and air is blown through the fins of the core. The
heater hoses transfer
engine
coolant
to the heater core, this allows the heat from the engine coolant to be utilized
and warm the passenger compartment. When a heater stops functioning determine what
type of failure has occurred to execute a repair. We have listed the most
popular problems below.
Heater Core
Troubleshooting ProcedureA. Check
Engine Coolant Level. Engine
coolant is used to heat the heater core if the vehicle is low on coolant the heater
core will stop working. The heater can not produce heat due to the lack of heat from
the engine coolant. Even if the engine is not over heating the coolant level can
still be low. Inspect the
engine coolant level in the coolant reservoir tank, coolant level should be
between the hot and cold marks. If the reservoir is empty the cooling system
may have a leak. Always check the coolant level when the vehicle is cold, preferably
over night. Check for engine
coolant leaks and repair as needed, then refill with coolant and recheck the
system.
Radiator Cap and Coolant Reservoir
B. Inspect Heater Control Valve. The heater control valve is used to shut
off hot coolant from entering the core when the heater is in the off position. A
heater control valve can be actuated by
vacuum
or an electric motor. Over the summer the air conditioner is in use, closing the
heater control valve. When this valve has been closed for several months it can
become stuck. To test for this condition start engine and allow to heat up to
normal operating temperature. Set the heater controls to the hottest setting.
Then, check the hose leading from the
heater control valve to the heater core. This
hose should be warm, if not the heater control valve is stuck and needs to be
replaced. After the repair has been made refill the coolant level to recheck
system.
Heater Control Valve
C. Check
Vacuum Feed. Most heater systems
are operated by
engine vacuum. This vacuum is used to actuate servos to move the
temperature adjustment doors inside the heater plenum. If engine vacuum is not
present the heater will not operate properly. To test for this condition remove
the vacuum feed line from one of the vacuum servos. With the vacuum feed line
removed insert a
vacuum test gauge. If no vacuum is present open the hood and
inspect all small vacuum lines from the engine to the fire wall and repair as
needed. If a hissing noise is present under the dash when the engine is running
a vacuum leak exists and must be repaired to restore
heater function.
D. Trouble Shoot Heater/Air
Conditioner Blower Motor.
An electrical motor is used to push
air through the
heater and
air conditioner system. If this
electric motor fails it will not
force air through the system. Ground
a
test light lead to a good ground
source, like a metal brace under the
dash, seat mount bolt or under hood
brace. Turn the key to the on position, check the
fuse in the heater or blower motor
fuse panel with a test light. Then lightly touch
the service port at the top of the
fuse on both sides. If the test
light illuminates on both sides of
the fuse, the fuse is ok and working
properly. If the fuse lights the
test light on one side it is blown
and needs to be replaced.
Power Distribution Center
If you
are unsure of the location of the
heater fuse consult a
repair manual. If the fuse
condition is ok, position the blower speed to the highest setting.
Connect the ground end of the test light to a known ground source. Then probe
both ground and power feed wires of the fan motor. The
test light should
illuminate on only one of the wires (fan motor failed). If the
test light
illuminates on both wires the ground source has shorted. If neither of the wires
illuminate the power source is shorted. To trouble shoot this style of problem a
wiring schematic is needed.
Troubleshooting
/ Car Heater
Failure
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2.How to Change a Cabin filter
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4.How to Tune Up with Throttle Bore Service
5.How to Replace a Radiator
6.How to Replace Fuel Filter
7.How to Read Trouble Codes
8.How Filters Work
9.How to Replace Front Brake Pads
10.How to Replace Rear Brake Pads
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