Whirlpool Dryer won't heat

[PaulC70]

Model WED6620HW1,  about 4yrs old. It quit heating last week. I opened it up and found the only piece WITHOUT continuity was the thermistor, so I bought a 2 pack online. Neither of the 2 new thermistors have continuity.??? The heating element, and both thermostats and thermal breaker all have continuity. 

What am I missing???

Thanks, Paul

[Budget Appliance Repair]

Thermistor will not read continuity - you need to have your meter set on a high OHMS setting as the thermistor, if I remember correctly, will be somewhere around 10,000 (10K) Ohms at room temp.

You most likely need to be checking the heat relay on the control board if everything else all checked out OK.

[Akshesh]

1) Verify the voltage to the dryer using a loading meter between L1 and L2 (240VAC).

2) When inspecting the heating element parts, disconnect one wire from each part.

Edited February 2 by Akshesh

[PaulC70]

BAR, where do I find the heat relay...?

[PaulC70]

So I found the control board and heat relay. The is no continuity at relay-dont know if there should be.??

Doesn't appear in can swap out relay, but rather have to swap entire board.??

Thanks so much! Paul

[Budget Appliance Repair]

@PaulC70 Yes, if the heat relay on the board is bad or has a bad solder connection to the relay then replacing the complete board is the normal procedure unless you know at least a little about electronics enough to know how to source a new relay, desolder old relay from board and solder in a new relay.

With the dryer running and having access to the control board you should have two wires with connectors that are accessible connected to the heat relay on the board.  With unit running and in a cycle where it should be heating and your meter set to read up to 240 Volts AC you would put each of your meter probes on those two wires, (one probe to each wiring - doesn't mater what color lead goes to what terminal).  If the heating system is OK you should see a reading of 220-240 VAC across those two terminals if the heat relay isn't closing correctly.

You can disassemble the control board and remove the actual circuit board from the plastic case to inspect the relay solder joints on the back side of the board.  There is a good chance you will find one of the relay solder joints to the heat relay burnt and it could be possibly repaired by cleaning and resolder if you know how to do that.

[Josh Smith]

Assuming your outlet is good, and the thermostats and element check out, they next thing I look for is the motor switch and the control board.  Look for a burnt solder joint on the board. The motor switch can be tested with a meter