Heater not working

Tiny
GEORGECOL
  • MEMBER
  • 2002 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 82,000 MILES
I have anti freeze in the resiviour When the radiator fans come on the temp is normal but I have no heat in the car it blows cold air The engine does not over heat. Please please please help me
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Friday, February 1st, 2008 AT 11:21 PM

18 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,554 POSTS
It sounds like you have a temperature blend door actuator that has gone out. Here is a guide and a diagram (below) to help you get the car fixed.

https://www.2carpros.com/articles/replace-blend-door-motor

This guide may help as well

https://www.2carpros.com/articles/car-heater-not-working

Please let us know what happens.

Cheers, Ken
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Tuesday, October 17th, 2017 AT 7:43 PM
Tiny
GREGBEGAY14
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  • 1 POST
  • 2002 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 190,000 MILES
My car's heater has just recently stopped working. Never had problems before and air conditioner works fine. Blower works. Not quite sure if it is the thermostat or the heater core.
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Wednesday, October 28th, 2020 AT 12:54 PM (Merged)
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Start with the basics.
Is the coolant at a 50/50 mix. I assume it has been flushed at least once by now.

Check the level is it good?

At operating temperatures are both heater hoses hot at the firewall or is one cold?
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Wednesday, October 28th, 2020 AT 12:54 PM (Merged)
Tiny
AVINCELETTE
  • MEMBER
  • 1 POST
  • 2002 CHEVROLET MALIBU
  • 50,000 MILES
Replaced heater blower and resistor because heater was not working at all. Now the heater only blows out air on 3 but not 1, 2, 4 or 5. What to do?
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Wednesday, October 28th, 2020 AT 12:54 PM (Merged)
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Use a meter to see if the switch is open or closed on 1, 2, 4, 5. If open, replace the switch. It may be a complete control module replacement.
MANUAL AIR CONDITIONING HEATER SYSTEM -2002 Chevrolet Malibu
Page 1 of 2
TEST E: BLOWER MOTOR MALFUNCTION

NOTE:
For correct circuit identification and connector terminal locations, see
CONNECTOR IDENTIFICATION and/or WIRING DIAGRAMS.
NOTE:
Definition: The blower motor operates in at least one, but not all, speed positions.
Perform DIAGNOSTIC SYSTEM CHECK
step.
Turn ignition on, engine off. Place mode switch in VENT position. Place blower motor switch in each speed position. If blower motor operates at desired speed in each speed position, problem is
intermittent. Check wiring and connections. If blower motor does not operate at desired speed in each speed position, go to next step.
Turn ignition off. Disconnect blower motor. Turn ignition on, engine off. Connect a test light between blower motor supply voltage circuit and ground. Place blower motor switch in each
speed position. If test light illuminates in each speed position, go to step 14. If test light does not illuminate in each speed position, go to next step.
If test light illuminates in maximum speed position, go to step 9 in maximum speed position, go to next step.
Turn ignition off. Disconnect blower motor relay. Turn ignition on, engine off. Connect a test light between battery positive voltage circuit of blower motor relay and ground. If test light
illuminates, go to next step. If test light does not illuminate, go to step 17.
Place blower motor switch in maximum speed position. Probe blower motor relay high blower motor control circuit with a test light connected to ground. If test light illuminates, go to step 8. If
test light does not illuminate, go to next step.
Test blower motor relay high blower motor control circuit for an open or high resistance. Repair as necessary, then go to step 22. If circuit is okay, go to step 16.
Test blower motor relay ground circuit for an open or high resistance. Repair as necessary, then go to step 22. If circuit is okay, go to step 13.
Turn ignition off. Disconnect blower motor relay. Turn ignition on, engine off. Probe blower motor supply voltage circuit with a test light connected to ground. Place blower motor switch in
minimum, medium "1", medium "2", and medium "3" speed positions. If test light illuminates in each speed position, go to step 13. If test light does not illuminate in each speed position, go to
next step.
Test blower motor supply voltage circuit between blower motor resistor and blower motor relay for an open, short to ground, or high resistance. Repair as necessary, then go to step 22. If circuit
is okay, go to next step.
1.
Under SELF-DIAGNOSTIC SYSTEM. Go to next. If test light does not illuminate

E:
Blower motor switch must be placed in appropriate speed position for blower motor control circuit being tested.
11.
Turn ignition off. Disconnect blower motor resistor. Turn ignition on, engine off. Probe low, medium "1", medium "2", and medium "3" blower motor control circuits with a test light
connected to good ground. Place blower motor switch in appropriate speed position for circuit being tested. If test light illuminates in each speed position, go to step 15. If test light does not

12/30/2011
MANUAL AIR CONDITIONING HEATER SYSTEM -2002 Chevrolet Malibu
Page 2 of 2
illuminate in each speed position, go to next step.
Test applicable blower motor control circuit of blower motor resistor for an open or high resistance. Repair as necessary, then go to step 22. If circuit is okay, go to step 16.
Inspect for poor connections at blower motor relay harness connector. Repair as necessary, then go to step 22. If connections are okay, go to step 18.
Inspect for poor connections at blower motor harness connector. Repair as necessary, then go to step 22. If connections are okay, go to step 19.
Inspect for poor connections at blower motor resistor harness connector. Repair as necessary, then go to step 22. If connections are okay, go to step 20.
Inspect for poor connections at HVAC control assembly harness connector. Repair as necessary, then go to step 22. If connections are okay, go to step 21.
Repair blower motor relay battery positive voltage circuit. After repairs are complete, go to step 22.
18. Replace blower motor relay. See BLOWER MOTOR RELAY under REMOVAL & INSTALLATION. After repairs are complete, go to step 22.
19. Replace blower motor. See BLOWER MOTOR under REMOVAL & INSTALLATION. After replacement, go to step 22.
Replace blower motor resistor. See BLOWER MOTOR RESISTOR
INSTALLATION. After replacement, go to step 22.
21. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY under REMOVAL & INSTALLATION. After repair, go to next step.
Operate A/C-heater blower system to verify repair. If blower motor operates normally, repair is complete. If blower motor still malfunctions, go to step 3.
Under REMOVAL &
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Wednesday, October 28th, 2020 AT 12:54 PM (Merged)
Tiny
DEREKDEREK
  • MEMBER
  • 1 POST
  • 2002 CHEVROLET MALIBU
  • 6 CYL
  • 2WD
  • AUTOMATIC
My 2002 chevy malibu heater works fine. It just will blow cold air and then switch to hot air and the cold again. It never constantly blows hot air, it always alternates. Settings 1-5 on the fan work just fine. I just dont get constant hot air
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Inspect and test the air blend door/ actuator
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
Is your heater controls on "Automatic" or "Manual" Does it blow hotter with higher engine speeds and cooler with lower speeds? I'll need this information to narrow it down.

If it fluctuates with engine speed, this would indicate either a thermostat that is stuck in the open position (rare) or a partial blockage of the heater core.

If the fluctuation in temp has no correlation with engine speed, then this would indicate a failing control unit, sensor, stuck blend door inside the HVAC unit, or a leaking vacuum line/solenoid that controls the blend door.
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
ERICK
  • MEMBER
  • 2 POSTS
  • 2001 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 850,000 MILES
Car heater blows out cold air
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,014 POSTS
Is the engine running at a normal operating temp? Have you checked to make sure the coolant is full? Have you tried replacing the thermostat? Finally, with the engine running, hot, and the heater on high, do both heater core hoses get hot?

Let me know.
Joe
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
BARKER76
  • MEMBER
  • 1 POST
  • 2001 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 74,000 MILES
I'm having trouble with the heat in my 2001 Chevy Malibu. It keeps going from hot to cold. It will blow hot for a few minutes then start blowing cold and just goes back and forth between hot and cold the whole time the heat is on, no matter what level I put it at.
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Gon under hood and monitor the heater core hose temperature with the air when its hot, and then check again when the air switches to cold.

Do the hoses stay same temp/
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
NATHANCOLE27
  • MEMBER
  • 3 POSTS
  • 2000 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 168,000 MILES
On my malibu my heat is very weak, especially on cold days. What I notice is that on a cold day, say 10 degree F. That the temp gauge on my dashboard will read at maybe 1/4 of max. On a warmer day in the 70s it will read at 1/2 of max. When everything was working fine the temp gauge read at 1/2 all the time, no matter what the outside temp is. Now it is varies with the temp reading on the dashboard.

I have considered it might be a stuck open thermostat, or something with the heater core. Though I know very little about the heater core. Any help would be great.

Thanks.
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
It could be a thermostat but is your cooling system full?
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
NATHANCOLE27
  • MEMBER
  • 3 POSTS
My coolant level is full. I haven't ever had any leaks or problems with the radiator so far.
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
MIKE H R
  • MECHANIC
  • 3,094 POSTS
The thermastat is sticking partly open, change the thermastat, msot times I suggest flushing the system with water when you have the themastat our but if it is that cold wait until it get warm out. I usually recommend cleaning the system out when changing the thermast as prementive maintance.
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
FAITHFUL
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 103,000 MILES
I have a 2000 Chevy Malibu.I have had the radiator flushed, a new thermostat, and a new radiator cap installed.I still get no heat. Only cold air. What could it be?
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)
Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
IF the cooling system was flushed, then there shouldn't be any restrictions in the heater core. This would suggest either a stuck heater control valve, stuck blend door or leaking vacuum line/solenoid (the last two are inside the HVAC unit)
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Wednesday, October 28th, 2020 AT 12:55 PM (Merged)

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