Heater not working in vehicle

Plugged heater core, blocked heater core, thermostat stuck open, temperature door not moving to "hot", fan motor not spinning, HVAC Computer not turning fan on this guide can help fix it.

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

Please run down this guide and report back.

At this point, you’ll need to determine if you have an issue with the heating/air conditioning controls inside the vehicle or an issue with coolant flow through the heater core. A quick and easy test is to check the temperature of the heater hoses running to the heater core. These hoses are smaller (about 3/4”) and will typically pass through the firewall on the right hand side of the vehicle. If one of the hoses is hot and the other is relatively cool, this indicates a blockage inside the heater core. If this is the case, you’ll most likely need to replace it. Use care as the hoses will be extremely hot. See the article below to see more detail on heater core replacement.

https://www.2carpros.com/articles/replace-heater-core

Is the engine running at a normal operating temp? With the engine running, hot, and the heater on high, do both heater core hoses get hot?

Let me know.

Joe

Does the engine reach operating temp if not check and suspect thermostat if engine reaching operating temp open hood and check heater hoses if both hot and if so suspect and check blend door and its actuator

Once the engine is well warmed up, feel the heater hoses under the hood. They should be too hot to hold onto for very long. If the upper radiator hose is that hot, but the heater hoses are not, start with flushing the heater core. Remove the heater hoses from the engine, then run water back and forth through them from a garden hose. That will dislodge any sediment that has collected in it. Be aware that if the coolant hasn't been replaced regularly, the heater core could be corroded and that sediment is sealing a leak. Sometimes when a heater core is flushed, it begins leaking after that.

If the heater hoses are hot, suspect a problem with the temperature door or its actuator. Heater systems are controlled with computers now, and those systems cause a lot more trouble than we had in the past.

Check coolant, thermostat, check for both heater hoses to be hot, bad heater core or blown head gasket from overheating

Roy

Actually, I think you are looking for a vacuum leak. The vents are actuated by vacuum. If vacuum is weak, the heat amy not make it to the vehicle. Also, there is a blend door that will do the same thing. It's located near the heater core. Check under the dash for vacuum leaks as well as under the hood from the soruce. With the engine running, you may hear a hissing.

Let me know what you find.

Joe

Okay, so you can direct air out the various vents like defrost, dash, floor but cannot get heat when you select a different temperature? Do you feel any temperature change at all?
If you go under the hood with the engine warmed up do both heater hoses feel hot?
(Image1) The upper hose is the inlet hose, if it is getting hot but the lower one is not you have a plugged heater core. If you have the rear heat option and feel no heat from either front or rear heating systems then this is the problem as the coolant goes through the front core then out and to the rear core and back to the engine. It could be a damaged tube under the vehicle as well. A plugged core is also the most likely issue if you have the split passenger/driver heat system with no heat to either side as both sides use the same heater core.

If both heater hoses are hot, then it is more likely the temperature blend door actuator that has failed. (Image 2) On this van this is not a hard repair. You start by disconnecting the negative battery terminal. Next you remove the isolation panel that is above the drivers side foot-well. Once it is off you can look above the gas pedal and you will see the actuators on the end of the HVAC case. (Image 3) The one marked with the 6 is for the blend door in the non-split system. To remove it you disconnect the wire connector, remove the two screws and pull it straight out. Reverse the process to install the replacement.

Once it is replaced you need to re-calibrate the system.

1 - Re-connect the battery.
2 - Turn the ignition switch to the "on" position.

3A - If equipped with the manual temperature control, press and hold the rear wipe/wash and re-circulation buttons for at least five seconds. The A/C heater control rear wipe/wash button LED and re-circulation button LED's will begin to flash when the calibration has begun. The process should complete in under two minutes.

3B - If equipped with the automatic temperature control, simultaneously press and hold the power and re-circulation buttons on the A/C heater control for at least five seconds. The ATC A/C-heater control delay and re-circulation graphics will begin to flash when the calibration procedure has begun. The process should complete in twenty seconds.

In both systems if the LED's or graphics continue to flash beyond the stated calibration times, it indicates that the controller has detected a problem and set a code. The LED's or graphics will continue to flash until a successful calibration is completed or until the vehicle has been driven about ten miles.

A faster way to determine if it is a faulty actuator without swapping anything out is to use a factory level scan tool to read the any codes stored in the HVAC control module. A bad unit will set a code.

Another thing you can try would be to run the re-calibration on it as it is. It may re-calibrate and start working if the system just lost the position of the actuator or if there is a code stored it will flash the LED's until you drive it the ten miles. Might help you pin it down as a plugged core would not set a code.