Why my heater isn't working?

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core. If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. it is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.

This sounds like you have low engine coolant or the temperature blend door actuator stopped working but to but sure this video and guide can help us fix it.

https://youtu.be/SNRb6pSwYuU

and if the temperature blend door needs replacement here is a guide that can help with diagrams below to show you on your car.

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

This guide can help as well

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

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.

You're welcome

Just to clarify the issue, when you start the vehicle and turn the heat on, the hoses going to the heater core are cold and the air blows cold. Then when the hoses get hot, the heater blows hot?

I am not sure I understand because that is normal. The coolant has to be heated by the engine before the air that is blown across it is heated.

Seems like this is not what your issue is so if you could clarify it, that would be great.

However, here is a guide that will help with heater issues in case it covers your issue:

https://youtu.be/SNRb6pSwYuU

Okay. Thanks. I think I understand. So to summarize when the engine heats up, the heater hoses go cold then hot, then cold and the heat in the vehicle follows this? This all happens even through the engine is hot?

If this is the case, I suspect you have air pockets in the cooling system. So when those air pockets go through you lose heat because you have air going through the heater core and not hot coolant.

Let's start with a pressure test to make sure you don't have any leaks. Here is a guide that tells you how to do that:

https://www.2carpros.com/articles/radiator-pressure-test

Then if there are no leaks we need to flush and refill the cooling system just to make sure it is clean and full. Here is a guide for that as well:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Check coolant level first if it is full then you may need a thermostat. low coolant is biggest problem with no heat which means you have a leak someplace. This sounds like you have low engine coolant or the temperature blend door actuator stopped working but to but sure this video and guide can help us fix it.

https://youtu.be/SNRb6pSwYuU

and if the temperature blend door needs replacement here is a guide that can help with diagrams below to show you on your car.

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

This guide can help as well

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

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

It sounds like you have a temperature blend door actuator that has gone out. Here is a guide to help walk you through the steps with diagrams below so you can see how to do the job on your truck:

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

Here is a guide for a general heater not working problems:

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

Here is a blend door actuator on your car (below) Also check the vacuum line from the engine to the firewall (small) to see if if its broken. Check for vacuum at the actuator line. Please let us know what happens.

Blend door and the blend door actuator are located on the heater case (plenum).

More information

Test: no operation in all temperature settings:
Start engine and bring to normal operating temperature. Turn blower motor switch to LO position.

Turn mode selector switch to PANEL position (MAX A/C position, if A/C
equipped). Turn temperature control to full COOL position and check for cool air
discharge. Turn temperature control to full WARM position and check for warm air
discharge. Rotate temperature control from full WARM position to full COOL
position. If air temperature does not change, go to next step. If air temperature changes, system is operating properly at this time.

Turn ignition off. Remove fuse No. 5 (15-amp), located in Central Junction Box (CJB).
Check fuse condition. If fuse is okay, go to step 4. If fuse is blown, replace fuse and recheck system operation. If fuse blows again, go to next step.

Ensure ignition switch is off. Disconnect electronic blend door actuator 8-pin harness
connector C229. Disconnect temperature control switch (potentiometer) 4-pin harness
connector C217. Disconnect CJB 34-pin harness connector C242 (located under left side of instrument panel). Measure resistance between ground and CJB connector C242 terminal

No. 15 (Light Blue/Pink wire). See Fig. 6. If resistance is more than 10 k/ohms, replace
CJB. If resistance is 10 k/ohms or less, repair short to ground in Light Blue/Pink wire
between CJB and electronic blend door actuator. See WIRING DIAGRAMS. Turn ignition off. Disconnect electronic blend door actuator 8-pin harness connector C229.
Turn ignition switch to RUN position. Measure voltage between ground and blend door
actuator connector C229. If more than 10 volts exist, go to next step. If 10 volts or less
exists, repair open in Light Blue/Pink wire between CJB and electronic blend door actuator.

Turn ignition off. Disconnect electronic blend door actuator control switch 63-pin harness connector C220. Measure resistance of specified circuits between electronic blend door actuator harness connector C229 and blend door actuator control switch harness connector.

If resistance is less than 5 ohms for all wires, go to next step. If resistance
is 5 ohms or more on any wire, repair appropriate wire(s).

Measure resistance between temperature control switch terminals No. 2 (Yellow/Light
Green wire) and No. 3 (Red/Light Green wire). See Fig. 7. Temperature control switch resistance should be more than 3000 ohms in full WARM position and less than 300 ohms in full COOL position. Resistance should change gradually as temperature control switch is turned from COOL to WARM and back. If switch resistance is as specified, go to next step.

If temperature control switch resistance is not as specified, replace temperature control switch. Measure resistance of Black wire between ground and electronic blend door actuator harness connector C229 terminal No. 8. See Fig. 7. If resistance is less than 5 ohms, replace temperature blend door actuator. If resistance is more than 5 ohms, repair Black wire between ground and blend door actuator.

Please let us know happens so it will help others.

Hi Jennp. Welcome to the forum. When you say it is not warm, do you mean the temperature gauge does not come up to normal or the air from the heater is not warm?

If the gauge is low, pinch off the upper radiator hose for a minute or two while the engine is idling. If the gauge comes up to normal, suspect the new thermostat as the culprit. If the radiator hose is too hot to hold onto for very long, the thermostat is okay. Feel the heater hoses next. If they are cool but the radiator hose is hot, suspect a plugged heater core. They can be back-flushed with a garden hose. Also, check for a water control valve. They are only on vehicles with air conditioning, and are controlled with a vacuum hose. Watch to see if the lever on the valve moves when a helper switches between the various heater/AC settings.

If the heater hoses are hot, suspect a problem with the door actuators on the heater box. On some models a pencil can fall down inside and block a door. Sometimes that causes the actuator to break.

Caradiodoc

It sounds like a problem with the blend door. It is a vent door that changes things from AC to heat.

This guide can help as well

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

Joe

Yes the a/c is going to come on when ever it is in defrost mode. If sounds like you have a blend door problem or blend door motor not working. here is a pic of both.