Why my heater isn't working?

Heater blowing cool air, where would I find the heater control valve to check it and/or replace it if it is faulty? Any other hints?

I dont think your truck has a heater control valve. The radiator fluid should always flow thru your heater core in your car. The temperature is controlled by the temperature blend door. The situate the heater core and close the door over it allowing air to flow thru the evaporator and into the ducting. When you select heat, the door opens allowing some air to flow across the heater core and into the ducts. The more the door opens, the more air is directed across your heater core. This guide can help us fix it.

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

If you are not getting warm air with full hot selected, it sounds like that door is not opening. Other possibilities are clogged heater core, bad electronic control going to the actuator for the temp door.
In looking at the electrical control circuit, it is very simple. There is a dedicated fuse for the Blend Door actuator in the junction box fuse/relay panel that delivers power to the actuator. It had a ground wire that goes to G200 ground. Three other wire go to the temp control switch. If you disconnect the plug to the hot/cold control knob, and jumper pin 1 and 2 together, that should drive the actuator to full warm. Short pin 2 to 3 will drive it full cold. Test it out and see if the motor will drive. If yes, replace the control switch. If not, check for power to the motor and a good ground. Powere and ground at the actuator, and still no movement. Replace actuator.
Good luckl.

I recently had my heater core changed along with the controle doors and accuaitorand my heater wont blow hot air I flushed the heater core check and rechecked vacumelines and connections but i still get luke warm air somtimesand cold the rest of the time.Also Can u tell me how to identify a heater control valve and where its located,and last question could the thermal limiter be the problem

You might try a new thermostat and make sure you get the system full of coolant mixture.

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

this should help

I can't remember whether the f150 had an electric blend door actuator or a vaccum pod. I think it has an electric control for the door. You need to locate the blend door and figure out what it has. If it is vaccum, stick a vaccum pump on it and see if it moves the door. If it has an electric motor, you should be able to see the shaft turn when the temp is adjusted. Hope this helps you. Please post your results, even if you have already fixed it, as this info will help others in the future.

When you set the heat to mix the air compressor starts. very little heat. To get max heat you have to set the control to vent so the air conditioner compressor will not come on.

The A/C compressor kicking with the heater is normal on an automatic climate control system. It sounds like you have a temperature blend door actuator that needs replacing. You could have something stuck in the blend door and also check the vacuum supply to the actuators and control head. Check out the diagrams (below).Please let us know what happens.

Sounds like you have either a bad heater control valve, partially plugged heater core or the blend door in the HVAC unit is not moving like it should. The blend door is cable controlled from the knob. Do you feel any temperature change when you move the knob? If yes then I would lean more toward checking the coolant flow through the core. Do both heater hoses get hot? If one is ho and one cold the core may be plugged or the control valve (if it has one in the heater line) may be defective.

Thank you so much for your help. With the vacuum hose drawing I was able to find a defective vacuum line. Every thing works fine now. Air is not very hot and takes a while to warm up. Probably a thermostat problem

Nice work, we are here to help, please use 2CarPros anytime. Let us know if you need instruction on the thermostat replacement. Here is a general guide.

https://www.2carpros.com/articles/replace-thermostat

Cheers, Ken

thermostat replaced with no problems

Good to hear, please use 2CarPros anytime we are here to help.

Cheers, Ken

have 93 Ford F150 but getting no heat. The radiator, heater core, and thermostat have been changed the vent doors work the coolant is full, just not getting hot air, why? Heat comes on but only cold air is coming out, no matter what the dial is set at.

Hello,

This vans get the heater core air locked. Jack the rear of the van as high as you can safely and then start the car and open the radiator to fill the system the tilt of the van will release the air pocket on the core,

Here is a guide to help you

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

This guide can help as well

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

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

I'm trying to narrow down the problem with my truck. I just replaced the thermostat in it thinking that was the problem. Here we go the blower motor for the heat comes on and blows good, however I can not get it to blow out heat. It is just cool air. I do not know if it is the heater control valve or what. I do no smell any anti-freeze inside the cab as if the heater core was leaking.

There isn't a heater control valve in the lines of the heater core. And with the engine running both hose into and out of the heater core were hot. Could this be one of the systems that is ran off of vacum? And if so where is the part that I might need to replace?

I do intend on making a donation to this site when and if I can get this problem resolved.

Thanks for the help,
Earl

Any suggestions?

If there is no heater valve, the system must work from a "blend door" which is located near the heater core itself. It allows fresh air from the cowl to enter the vehicle, and based on how much heat you want, the blend door allows the air to pass over the core.

Check to make sure there are no cables or vacuum lines running to that area which are disconnected. Also, look for a vent door that appears to regulate the air passing over the heater core itself.

This guide shows the broken vacuum line problem with these trucks.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

and

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

Here it is for your car (below)

Please let us know what happens.

Cheers, Ken

Bought this truck used a couple months ago. When turning the blower from off to defrost, I would here a some what loud click or slap. Sounded like something closing? Warm air has never come out from the defrost, however, it would work on the floor setting. As of today, I no longer hear the sound when switching from off to defrost and I no longer have warm air on any setting. Based on what I have read I'm guessing it is some sort of actuator? When I first got it, I had a back flush done that seemed to help, but that was temporary. Any ideas?

Hello,

This does sound like an actuator problem. Here are a few guides that should help you run down the problem:

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

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

Tell us what you find out.

Thanks,
Alex
2CarPros