I have an April Air 600 humidistat with an outside temperature sensor. What is the procedure to test a temperature sensor to see if it is working.

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    You want to know if the actual sensor is functional, or you want to check and see if it is hooked up and "doing something" to the system? – JPhi1618 Dec 18 '19 at 16:19

I have an Aprilaire Model 55 TCH (Temperature Compensating Humidistat). Do you have an ohmmeter? This is what I found in my notes: enter image description here

I'm thinking the sensors haven't changed between models. I would measure it at the TCH to make sure there isn't any discontinuity between the sensor and the TCH.

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  • if in need of an "ohmeter", one can get the cheapest possible multi-meter, sometimes they even give them away at harbor fright... – dandavis Dec 19 '19 at 19:11
  • thanks steve I do have an ohm meter. I assume I disconnect from the humidistat and test for resistance and compare to chart to see if it is functioning. then how do I test to see if it is affecting the humidistate – Jeff Allen Dec 19 '19 at 20:50
  • Yes to testing the sensor with an ohmmeter. I keep my humidity on the 'edge' of causing condensation on windows. Occasionally, when the temperature drops very quickly, I'll see just a bit of condensation which disappears as the humidifier backs off the humidity because of the colder temperature outside. That is how I know it is working. I don't know how to actually test it. – Steve Wellens Dec 21 '19 at 5:17

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