How to test an NTC thermostat (Diplomat/Smeg)

[akbmcf1]

Hi all,

I was hoping someone might be able to advise on the way to test an NTC thermostat as used on my Diplomat ADP8902 (and some Smeg machines too) - it's this one: http://www.espares.co.uk/part/dishw...76/0/970446/970318/dishwasher-thermostat.html

I've tried testing it for continuity but am assuming that as it is, in essence, a heat-activated switch, then the fact it doesn't have continuity is not an indicator of whether it is working.

I set my DMM to resistance, and am getting an infinity reading (display reads 1) at room temperature and when I put the thermostat in boiling water. Would this indicate the 'stat is at fault?

Reason I ask is that I bought a new one to try and cure the problem with my dishwasher (if you want to read more, check out my other thread //www.diynot.com/forums/applia...asher-not-progressing-finishing-cycle.350854/, but this hasn't cured the problem and the new one returns the same results right out of the box as the 'old' one did...

Many thanks in advance for your help.
Andrew

 

[Terox]

It looks like a thermistor

Set your multimeter to read at it's highest resistance option. Thermistors can have very high resistance.

Basically It changes resistance as it's temperature changes. so you wouldnt expect it to be open circuit.

The best way to check it is in range is to compare it with a new one unless there is a service manual available for it (Doubt it) that states the values you should get at X,Y,Z temperatures.

It will be connected to a PCB, the PCB will monitor the resistances of it and react to them, shutting the heat down, going to the next stage of the program etc