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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22242
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Matt! The is a clicking then slight grinding noise coming

Resolved Question:

Hi Matt!
The is a clicking then slight grinding noise coming from the heater when it has been on for a while. Even when I turn it off, it still continues for a few minutes. Last exactly 16 seconds after ignition is turned on when it's been playing up. Can stop for 1-2 days, then returns. I have been told it may be the hot/cold actuator flap.
Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
Hello

a faulty flap motor could be this issue

can you tell me what make and model of vehicle this is?
Customer: replied 2 years ago.
Toyota Avensis 2.2d 2008 regd.
Expert:  Matt replied 2 years ago.
Hello Phil

to locate the flap motor / servo you can usually look up under the dash towards the center of the vehicle and see the white plastic lever moving rapidly back and forth.

The purpose of the servo is to mix cool air from the A/C or outside with warm air from the heater to match the temperature you have set. The white lever has a travel of 90 degrees.

One extreme is all cold air (no hot air mix), and the other extreme is all hot air. The A/C computer sets the position of the servo based on the air temps and the desired temp setting. For the servo to make the noise, it has to be in the middle region between the two extremes. This is generally when the set temp is close to the actual temp. You can try moving your set temp from very cold to very hot and watch the white lever move from one extreme to the other.

Note that if it's too hot or too cold, you might not be able to get the servo to stay in between the two extremes. When the lever is in between the two extremes of travel, it should be very stable although it may move a bit every minute or two

so I'd suggest replacing this servo as the next step
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