I have a Whirlpool Senson Dryer, model Whirlpool geq9858jt0 that turns on when the button is pushed, but stops when released so it won't stay on. The drum turns, but no heat. I've checked everything I can think of based on lots of research.

The vents are clear of any excessive lint. Checked voltage and the breaker, I have 240 coming in at the terminal. The timer shows continuity when set to timed dry and open when off. The heating element shows continuity. The High level thermostat (lower one) and the Thermal Cut Off thermostat (upper one) both show continuity. I checked the thermister and had an about 12ohms (I think, didn't write it down), and the thermal fuse for continuity. I swapped the 2 relays in the panel (I did this yesterday, i believe one is for the motor and other for heat - the relays are identical and swapable).

I also checked the heating coil and High Level Thermostat with power - no voltage detected when holding the button in and the dryer running.

What did I miss? Guess this isn't one of the "easy" ones.

Thanks for your help....

 

These motors have a start winding and a run winding. When you push the button, you energize the start winding, which starts the motor turning. Usually there is a centrifugal switch which disconnects the start winding and energizes the run winding after the motor reaches a minimum speed. In all likelihood, either the centrifugal switch is stuck or the contacts burned, or the run winding is open. I would suggest that you check the centrifugal switch first and see if the weights allow the switch to change "modes".

Most dryers have an interlock that prevents the heating element from turning on if the motor isn't running, to prevent the heating element from overheating and possibly causing a fire.

 

Bob, great explanation about the motor circuit. I read that there was a switch in the motor that could cause this, but as I understood it was a rare issue. The motor is the last check and based on what you said it's probably my issue. Wasn't sure how to test this circuit, so I found this youtube video
https://www.youtube.com/watch?v=6wnEEIAsmok

I'll test the motor and report back.

Thanks for your advice

 

I tested the contact switch on the motor. Pushed the centrifugal switch disc and the contacts on the switch are switching on and off as they should (both sets of contacts.) There was some black soot on one of the center contacts, so I cleaned it with emery cloth and cleaned all contacts with spray contact cleaner - but again, they were already working.

What is left to check? Or is it possible I am checking the components wrong?

 

There should be more than two sets of contacts on the motor switch. I've been trying to find the tech sheet for your unit but have not had any luck. It will be inside your appliance.... possibly in the bulkhead area. With that you can diagnose the problem. The two numbers below are the tech sheets for the Gold series.

tech: WPL-LIT3978618
wiring: WPL-LIT8299797

 

I've been researching more. On the motor relay, the 2 PK/BLK wires should show 48VDC according to what I've read, but when I connect my voltmeter it shows 0V with the start button held pushed and dryer running or when I let go of the start button (and the dryer stops). I've read this means the control board has failed. Can anyone confirm I tested this correctly and it's meaning? Thanks

 

It will be on the tech sheet.

 

As PJmax has pointed out, you need the tech sheet to troubleshoot. The spec sheet should contain a schematic and ladder diagram at least. The schematic shows how the electrical/electronic components are connected (not physically wired) and the ladder diagram is roughly a timing diagram where one can follow the sequence of the electrical/electronic components being energizes or deenergized for the operation selected. For example, does the start switch provide 120 vac directly to motor or is there a another component between the switch and the motor? Is the circuit providing the 48 vdc to the start relay involve the start switch? There are 2 different voltages involved here. Without the spec sheet one is left guessing making successful troubleshooting difficult. Hope this helps.

 

Sorry guys, here is the tech sheet (at least the schematic parts). I'm not a professional so I'm really not sure how to read it. But I marked the areas I'm talking about.

I think I checked it correctly - probes on each of the 2 pink/black wires on the motor control switch, I'm getting 0 volts whether the start button is pushed and held, or released (and the dryer stops). If I did this correctly, then it looks like the Thermister or the control board? I tested the ohms on the thermisiter, but not sure that's accurate enough. Based on another site forum, the control board is often the issue when 48V isn't detected.

I pulled the control board and found dark discoloration around 3 diodes. See pic If it is the control board, it's no longer made and very difficult to find. On ebay, there is a company that repairs them for $150. Kind of expensive unless I'm sure this is the faulty part. I'm tempted to replace the diodes near the discolored area, but what caused them to overheat? That's out of my area of expertise!

 

MISTAKE: I circled the heater relay in the schematics. But I checked the motor relay pink wires p2-7 and p3-2 and found 0 volts. I now see I should have checked the heater relay P3-1 and p3-2 for 48V also. I just checked and found 0 volts on both the heater relay and the motor relay.

 

Another Update: I unsoldered the 3 discolored diodes and checked them with a meter - all three are shorted. I researched and found replacements from Digikey (original 4745AP, replacements are 1N4745A) . Once they arrive, I'll solder them in and report back.

Also found this link that confirms this is a very common issue: 110.68932790 My $2.87 Kenmore 90 Plus Series "Evenheat" Repair - Board 3402605 | Applianceblog Repair Forums

 

They took a simple motor start circuit and complicated it with motor current monitoring.
You push the button and the motor starts. You let go of the button and the motor stops.
It's all controlled on the control board.

 

Final Update: I replaced the 3 diodes on the control board and the dryer works again! Less than a $1 parts plus about $4 for shipping (digikey has a minimum for shipping). Pretty simple repair if you know what to look for - so hopefully this will help others in the future.