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KHHS179LSS Microwave where is the humidity sensor located

KitchenAid OTR microwave KHHS179LSS. Error code F3H says the humidity sensor is bad part #4393808 or sub #8206446.

Where is the physical location of the sensor ?
Does the unit have to be taken down to change it?
Is it really necessary to also replace the board part #8205813 which is $150 or more.

Appreciate all the advice I can get. My son is an electrician and he will do the work.


Microwaves , Appliances
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2 Answers from these members:
Manage My Life
Hello, It is always good to have someone that you know to be able to fix appliances that can be expensive to repair. You can visit the ParsDirect website and enter your model number you will have a visual of all the parts in your microwave I have provided the link below. I hope this helps!
by Manage My Life
June 27th, 2010
Answered in 22 minutes
0 votes
Manage My Life
To locate the humidity sensor go to

or look on the parts diagram if you have one.

Go to the "airflow parts" page. Item 17 is the humidity sensor and it is located under item 1. The parts on this page are located behind the grill across the top of the microwave. Some technicians replace the humidity sensor without taking the oven down. Other techs think it is easier to take the oven down to replace the humidity sensor.

Your son probably has a volt/ohm meter and can test the resistance of the humidity sensor. If he can test the resistance, you will know if the problem is in the sensor or the control board. You do not need to replace both parts to cure the problem.

To test the humidity sensor remove the control panel from the microwave. Find the 3 wire plug of the sensor on the back of the control board with the white, red, and black wires and disconnect it. Perform the tests as illustrated. If the sensor is good replace the control board. If the sensor fails the test, replace it.
by Manage My Life
June 29th, 2010
0 votes
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