The HVAC temperature will not switch from hot to cold and back why?

Good morning,

The actuator is the most common failure for the temperatures not changing. It is on top of the heater case as your tech stated. This guide and video will show you how to change it.

https://youtu.be/Eqf-H3COtSo

and

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

I attached the pinout of the module as you requested.

https://www.2carpros.com/articles/how-to-check-wiring

I also attached the actuator replacement procedure and location of the blend door for you. Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Truck blows hot air no matter what setting it is on. The system is full of Freon. Compressor goes on and off along with the condenser cooling fans operating normally. I've noticed the high pressure side where the orifice tube is located icing over going in towards the firewall. Also, before the start of all this, there was a popping noise coming from under the dash towards the floor board on the passenger side. I've also noticed that once the popping stopped, that is when it started blowing hot. The blend door seems to be operating correctly, but not exactly sure where the temp control actuator is located on this particular model. Any help on this would be much appreciated. Thanks!

Hello,

This definitely sounds like it could be a problem with your Heating Ventilation Air Conditioning (HVAC) blend door actuator. I have included diagrams down below in the diagrams down below of the location of the blend door actuator for your vehicle. I also have included a link for you to go to:

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

Please go through the guides and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Is Fig. 2 for a dual climate control and Fig. 3 for a single? Just want to make sure im reading this right because i have a single control unit and not a dual.

Hello again,

Figure 2 is Auto Climate Control and Figure 3 is for Electronic Control. The way I see it is Figure two is when you set a desired temperature and the vehicle maintains that cabin temperature for you, and figure 3 is for you have to manually adjust the temperature yourself. It must be an option on your vehicle.

Thanks,
Alex
2CarPros

i have discovered that the heat/cool blend actuator is not always working and that I may need to replace it but I do not know where it is located, when I took the (3) 7 mm screws from under the dash near the floor, then removed the cover I did not see any actuators just more plastic, so before I start pull the whole thing apart or paying some crazy amount of money I was wondering if you knew where it is located or even have the exact diagram for my truck? Thanks.

Hello,

Here is a guide to help you see where all blend door motors are with diagrams below

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

Try pulling hvac fuse under hood for 60 seconds first as it may reset the actuators. see pic for temp actuator, if you have both left and right temps this is also for right side. Check out the diagrams (Below) Please let us know if you need anything else to get the problem fixed.

The driver side vents would flip from AC to very hot air. I watched the video and replaced the blend door actuator. Did the re-calibration by disconnecting the battery for about fifteen minutes, reconnect and turn the truck on for one minute. Turn off a few minutes and turn on again two minutes. I could hear a ratchet sound during the process. Now it is hot all the time and very little air volume coming from the passenger side vents. What can I do to fix this? Thanks.

Looking at your diagrams, it appears I replaced the wrong actuator. The one I replace is shown in your photo below under the cowl on the passenger side. Is the correct one under the top of the dash? Do you have a video showing how to get to it?

That is correct. That is not the actuator. The correct one is under the dash, left side above the fuel pedal.

I attached a picture and the procedure. Easy replacement.

Roy

REMOVAL PROCEDURE
1. Remove the I/P insulator panel.


imageZoom/Print

2. Disconnect the electrical connector (1) from the left air temperature actuator (2).
3. Remove the screws from the left air temperature actuator (2).
4. Remove the left air temperature actuator (2) from the HVAC module assembly (3).

Now I am confused. According to what I have read, the actuator on the left over the gas pedal is the mode door. Most of the videos I have seen state that the hot/cold on the driver side is regulated by the actuator on the right side underneath, the one I replaced. I even think the 2CarPros video stated or implied that. But the diagram on the 2CarPros article suggested that the driver side hot/cold was the actuator on the top right side (not the recirculate). So I am thinking that I did replace the correct actuator, but that either my replacement part is not correct or I did the re-calibration wrong.
I opened the actuator that I took out. It did not have the metal under the large gear, nor the track on the board like all the ones in the videos have. I do not know what that could mean. Outside, the actuators look the same.

If you have dual control or left and right control, that is the left side.

If you have only one control for both sides then it is the one on the right side.

Since you said only the left side goes warm, it sounds like you have dual control.

Roy

I installed the actuator and did the calibration. The air was coming out hot but not as hot as sometimes which means that the door was in the half open position just the way the actuator was installed.
I looked at the plug and found two rows of contact holes. The bottom row has the metal contacts. My plug is going into the top row (based on how close the pins are to the edge of the housing). There appears to be some metal in the top row. Will it work to plug it into either row?

I watched you video on replacing the blend door actuator. I successfully removed the old, and installed the new. It was still blowing hot, out of the driver's side. It seems like the actuator is being told, to turn the shaft, to heat. I removed the new one, and tried seeing if the actuator would move, when adjusting temp. Kind of at my wits end, on this one. Any advice, would be appreciated.

Here is the video

https://youtu.be/Eqf-H3COtSo

you can try tip that I'm sending also try removing hvac fuse inside truck for 60 seconds then reinstall. Do not move any hvac controls after reinstall. wait another minute and see if it straightens out. then look at first pic that is a tip that other mechanics have found.

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

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

The plug only goes on one way.

Are you sure you have the correct actuator?

Roy

After I wrote above I looked at my old actuator. Its pin placement is identical to the new one. I can only assume that there are contacts in both holes. The 2 / 3 pin lineup is correct. And, as you said, the plug only goes in one way.

I have the manual temp control and I know my actuators do not work. I have replaced the actuator located at the bottom over the transmission tunnel. It moves with the temperature control. I still cannot move the air off the defrost and don't think I get recirculating air. So, here is my question. Per your diagrams, it looks like there are a total of four actuators. When I look for the part, I find it confusing to find the correct part number for each actuator even though I have the RPO codes. I installed Dorman 604-112 and it works great. Is it possible that this same actuator will work in all four spots?

It is rare for all of the actuators to fail at once. In your case it sounds like the mode actuator on the left side (drivers side) at the top of the case has failed. It controls the floor/dash/defrost modes. I believe you can change it without taking the entire dash out.

In the picture six is the mode door actuator, two is the re-circulation door actuator, four is the passenger side blend door actuator and the one you replaced is the drivers side blend door unit. Depending on the actual option package and controls the actuators are the same for the two blend doors, the mode unit is different as is the re-circulation actuator.

Here is a guide that can help you too.

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

I appreciate you providing some light on this topic for me. Donation sent! Thanks...

Good to hear, Steve W. is one of our best. Please use 2CarPros anytime we are here to help.

Cheers, Ken

when I turn the heat on for a cool morning, and then while driving, if I turn the air conditioning on the heat stays on until I stop the truck and turn the ignition off for about 15 minutes, then most of the time, and again I say most of the time, the air will work, but not every time, sometimes it takes overnite before it will work properly. I was told by a GM factory mech it was an acturator valve. If this is true, can you tell me where it is located. thanks: jim

Air temperature actuator is on the bottom of the heater case. This is a picture of manual system, auto temp is similar.

After installing a replacement actuator it turns in the wring direction. Like when you switch to cold it blows hot when you switch to hot it blows cold any ideas?

Hi and thanks for using 2CarPros.

Either you got a bad actuator or you switched the polarity position on the plug (forced the plug together opposite to how it should go.) The directions of power to the motor determines what direction it will move. If it is plugged in backwards, this is what will happen. Recheck to make sure that isn't what happened.

Let me know what you find.

Joe

how to replace the actuator which controls the heat?

I attached some additional pictures and a flow chart for you.

Check the voltages at the connector for the blend door. I identified the power and ground for the motor.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Roy

When I have my defroster on in it is blowing hot air sometimes it switches to cold air automatically. I sometimes have to run the control all the way too cold then back to hot to get heat.

It sounds like there is an issue with the temperature blend door and/or blend door cable or actuator. This particular model vehicle used two different types of control systems depending on whether or not it was equipped with air conditioning. Attached below are two different diagrams of these systems. The first is the heat only version which uses cables to control the blend/mode doors. The second is the system with A/C which uses electronic actuators for these doors.

If you have heat only, have someone move the temperature control while watching the cable/lever at the lower left area of the heater housing. Based on you description, it sounds like the cable may be loose where it attaches to the door lever.

If you have A/C, remove the glove box assembly to access the door actuators. Looking at the second diagram below, you can see that the blend door/temperature actuator is at the top, toward the center of the housing. Again with someone moving the temperature control, observe the actuator and make sure the linkage is all in place and not loose or broken.

Let us know what you find!

I was told the blend door motor might be stuck in the hot position. It blows hot air to the drivers side floor board even with the heater/AC controls off.The heater and defrost work though when needed. I just can't get cool air from A/CI've gotten the Freon filled so that's not the problem.I want to fix it myself and just want to know whys it doing this and how do I fix it. Thank you

Welcome to 2CarPros.

The blend air door actuator is under the dash on the HVAC unit. Here is a link that explains in general how one is replaced:

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

Here are the directions specific to your vehicle. I attached two pics. One shows the HVAC unit under the dash, and the other, I circled the actuator in question.


REMOVE OR DISCONNECT
1. Battery ground cable.
2. Instrument panel compartment for excess.
3. Electrical connection.
4. Screws.
5. Actuator.

ADJUST
1. Install the battery ground cable.
2. Electrical connection to the actuator.
3. Turn the ignition key to the accessory position.
4. Allow the actuator to position itself.
5. Turn off the ignition key.
6. Disconnect the electrical connection from the actuator.
7. Disconnect the battery ground cable.

INSTALL OR CONNECT
1. Actuator to the heater assembly.
2. Screws.
3. Electrical connection to the actuator.
4. Instrument panel compartment.
5. Battery ground cable.

Let me know if this helps or if you have other questions.

Take care,
Joe