Climate Control

02/01/2022

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Climate control “chuntering” Heat Servo

Do you have an irritating chuntering noise coming from under your dash when the heat selector is in certain positions or comes and goes randomly?

If so, the most likely cause is the climate control heat servo hunting about on the bottom of the climate control heat exchanger.

The servo is located under the climate control heat exchanger, just above the passenger side foot well vent. You will hear the noise coming from what looks to be a hopelessly complex mass of wires and connectors just above the vent as the servo hunts back and forth to maintain it’s position. The reason it does this is because the contacts inside the servo motor become dirty and require cleaning.

To clean the contacts you will need to remove the servo which, despite first inspection may seem impossible but, Toyota thought the design out very well and the whole thing can come free with ease.

To gain access to it you will need to remove the trim below the glove box and the glove box it’s self.

Firstly - Turn on the ignition and set the heat control to the central 25’ position and turn off the ignition.


	Remove the bracket holding the servo connector and the climate control calibration connector and push them out of the way. Remove the 3 screws outlined in the photos here. This will free up the bracket and the auto fan speed switch which can both be pushed up out of the way.

Next, to gain access to the rear screw holding the servo in place you will need to remove the foot well vent.

This is simply held in place by a screw located above it as per the photo here. You may miss it at first glance as it tends to hide behind the servo cables.

Remove this screw and pull the vent off, it will unclip from the bottom as you pull it.

Once the vent is removed you will be able to remove the rear screw using a Phillips ratchet bit. They are not usually tight so, can be taken out with your fingers.

The servo will now be free to pull out of it’s mounting recess and unplug.

You do not need to worry about the actual mechanical connections as these just sit in place on rods so just pull out.

Now you have the servo free, pop it gently in a vice or similar to hold it. Place a piece of tape under the position indicator and draw round it so you can put it together again in the correct position without worry.

Remove the 5 lid screws and pull the top upwards and off to reveal the inner workings. There are no springs or loose components to worry about in this assembly.

Inside the motor you will find several sets of contacts, some sprung copper wipers and a resistive track. It’s these components that become dirty and make poor contact causing the motor position to hunt continuously.

Clean the PCB and contacts up carefully, simply wiping them over with a clean cloth should be enough.

Gently ease the sprung contacts out very slightly as these compress over the years and again contribute to the problem.

Before you reassemble the motor apply a small amount of Vaseline to the PCB contact area, just as it was found, to lubricate the wiped surfaces.

When you refit the lid, line up your lever match marks before engaging the drive gear then pop the screws back in.

Once done just refit the servo back into the climate control making sure you engage the heat control flap lever when you offer it back up and again. Likewise, make sure the auto fan speed lever is in place before putting in the screws.

Refit in the reverse order of removal otherwise you will prevent access to all the screws and start swearing :0)

If you want to you can plug the servo into it’s loom before refitting & adjust the temperature control, just to check all is running correctly.

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