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Cold Heat Hot AC Diagnose Temperature Problems In Your Car or Truck

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Cold Heat Hot AC Diagnose Temperature Problems In Your Car or Truck

Created on: 2020-09-16

AC blowing hot or your heat blowing cold? Before replacing the AC refrigerant, or heater core, it could be the temperature control blend door is stuck, or the actuator has failed.

When you turn your air conditioning on, do you have heat blowing out of one side and ice cold AC coming out of the other? That's what we're gonna talk about in this video.

This happens to be a GM vehicle with a dual-climate system. Most other vehicles should work the same or very similar. What the dual-climate system actually does is it allows the passenger to have a different temperature than the driver. If the passenger is a little bit cold, they can turn the heat up a little bit and they can be warm, and vice versa. Now how this system works, it actually has two different actuators and two different doors that can blend the temperature.

Now you could have these temperatures set, so one side is at 90 degrees, one side's at 60 degrees. That would mean hot air is coming out of one side, cold air coming out of the other. Now the easy fix for that would just be adjusted so they're at the same temperature. Now, in some cases, you may have the temperature set to the same level, you'll have hot air coming out of one side, cold air coming out of the other. In that situation, something's gotta be addressed. Now, if this happened after you disconnected the battery or had to jumpstart your vehicle or your battery died and you put a new battery in, there could be something wrong with the programming of the module itself.

Now, if you go to start the vehicle for the first time after the battery was disconnected and you move these controls, the HVAC control module does a self-test and tries to find where the blend doors are located. If you interrupted that, they're not gonna be in the accurate spot. That needs to be recalibrated. If that was the case, sometimes what you could do is disconnect the negative terminal on the battery. Let it sit for a while, give it maybe five minutes and then reconnect the terminal. When you go to turn the key on, don't touch anything on the HVAC control head. Hopefully, that resets.

Now, before you did that, if you have a powerful scan tool, it's a good idea to check the HVAC control module for codes and see what pops up. If you have any temperature control circuit codes, then disconnect the battery isn't gonna fix your problem, there's gonna be other issues. Now with the scan tool, what you can actually do is see where the position of the door should be, which in this one, the left door is the one that's giving us a problem. It's commanded to 255, that's just a value and the actual door position is at 30, which isn't good. If you move the adjustments, it should move the command and the actual should go along with it. In our case, we have a problem with the actuator, it's gonna need to be replaced. And this one is on the passenger side and this is the commanded position and the actual. These ones are working properly and that's how it should look.

Now, the actuator that's bad on this vehicle is on the driver's side. Right above the gas pedal, it's connected to the HVAC box right there. This is what the actuator actually looks like. Now, this side goes to the door that goes into the heater box. This is what the connector connects to, and there's where the screws go in.

In most cases, most vehicles will have the driver's side actuator on the driver's side, just like that, passenger on the passenger side, but some vehicles it'll be on the bottom of the heater box or on the top of the heater box. On some vehicles, you may notice a clicking noise coming from this actuator, and there's actually gears inside there. And in those cases, most of the time, these need to be replaced. And if you take the cover off this and this is what it looks like inside. There's an electric motor, and that will turn these gears. And sometimes these gears wear out, they're plastic. You could get a flat spot and that's gonna cause this not to work properly.

And, as you can see, this one actually has a crack in it and that can potentially cause the gear to not be able to turn the shaft right here, and that's most likely why this one actually went bad. Now you could always have a mechanical problem with one of the doors being stuck, something is broken or a temperature sensor isn't working properly, or even the head unit itself isn't working, but most of the time, it's the actuator itself.

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