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Common C5 Climate Control Heating and Cooling Problems

Technically Speaking

James Berry Jun 28, 2019
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Question: I wanted to let you know that I look forward to getting the magazine in the mail every month. I am a little older and still enjoy thumbing through a paper copy of a magazine. I guess it reminds me of my youth.

This is my situation. I own a C5 Corvette with a Dual Climate Control System that has been problematic since I have owned the vehicle. It worked perfectly through most of the summer, but I have not touched any of the controls in months. Recently, I adjusted the temperature up a little and it started blowing out full hot on the driver-side but the air is blowing cold on the passenger-side. Ever since I touched the controls there is a clicking noise coming from under the dash every time I start the car.

Do you have any idea what I could look for? I would like to try and fix it myself since I have spent so much on the air conditioning system for problems in the past.

Thanks for any insight into this problem.


Answer: Paul, I also love to browse through a real magazine. I will even pick up some of my old issues from time to time.

All car models—no matter the manufacturer—have some common failures and the Corvette is no exception, but, in general, the Corvette is a great vehicle. I believe I can help you with your problem. It is a common failure on GM products, and, yes, I think this is something that you probably can repair yourself.

You gave me the answer to your problem when you said you heard a clicking coming from the dash. It is most likely that the blend air door actuator has failed and will need to be replaced. There are two blend air door actuators, one for the driver side and one for the passenger side.

Lucky for you, the driver-side blend air door actuator does not require removing the dash cover. You will need to remove the bottom panel in the driver-side footwell that houses the OBD-II diagnostic port (knee bolster). Remove the amplifier box and then you can locate the driver-side blend air door actuator. The actuator has a wiring connector and two screws holding it in place. It is not easy to get to but just be glad the actuator that failed in your vehicle is the one on the driver side.

To access the passenger-side blend air door actuator, you must remove the glovebox and dashboard cover and you will find both the driver- and passenger-side actuators on the top. We have covered removing the dash in several past articles. It seems like this is becoming something almost common.

After replacing the blend air door actuator there is normally no programming or calibration needed. They are simply plug-and-play. After replacing the actuator and then when you start the vehicle with the air conditioning on, the actuator will go through a self-test and calibrate itself so don't move any controls for the first two minutes after you start the vehicle. If there is a problem and it did not self-calibrate simply perform a global reset.

If you had this problem without the clicking issue I would have recommended you record the climate control fault codes and perform a global reset, which basically means there is a communication problem. On a C5 Corvette, the first thing to do is to drain the capacitors. Basically you are rebooting the system, forcing several systems on the vehicle, including the blend air door actuators, to go through a self-calibration. Please refer to Technically Speaking in the September 2018 issue for this procedure.

If any of the climate control fault codes indicate a blend air door issue, normally the blend air door is the problem. Well, Paul, I hope this helps you out and by the way I forgot to mention you will need to do your best impression of a contortionist when you replace that actuator. Vette


The blend air door actuator's most common failure is that over time the plastic gears can split or become worn and strip the teeth out.


Notice that the blend air door actuator is clocked (the white female portion of the actuator), when you install the blend air door actuator just fit the actuator to the blend air door itself and turn the door and actuator until you can get the actuator to line up with the mounting tabs. When you start the vehicle the actuator will go through a self-calibration and reset itself. So there is no need to try and clock the new actuator to the old one.


Once you access the actuator it is held in place with two 7mm bolts and a wiring connector. When you line up the actuator notice there is an alignment peg.

Photography by James Berry



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