Rank: Member
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Joined: 11/22/2009(UTC)
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My dryer is turning but not heating. So I:
· checked the lint/airflow situation. It was fine - lot of flow, nothing plugged up.
· took the back off the appliance, and vacuumed everything inside and out. (Boy, it gets grungy back there!)
· checked the circuit breakers (fine)
· measured the voltage going into the appliance (240V - fine).
· checked continuity on the Cycling Thermostat, Thermal Fuse, the heating element, and the Hi Limit Thermostat. All fine.
· checked continuity on the Thermal Cutoff. NOT FINE!
So, I ordered the 279816 part, which came as a kit that included both the Thermal Cutoff and the Hi Limit Thermostat. The instructions that came with it said, "If the thermostat looks like this... ", to also replace the Hi Limit Thermostat and do something with a jumper wire. Since my Hi Limit Thermostat did NOT look like that - the picture showed a dangling contact that I did not recognize - I did NOT replace the Hi Limit Thermostat. I replace the Thermal Cutoff only. Then I fired up the dryer. Heat!
Things worked fine for a load or two, but now I’m back to where I started – the dryer is turning but not heating! 8^( The Thermal Cutoff I replaced no longer has continuity. No change in the other components I checked earlier.
Did I screw up by NOT replacing the Hi Limit Thermostat?
I have two college kids that are going to be home in a few days. They will dragging lots of dirty laundry with them, no doubt!
Thanks - Bob
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Rank: Member
Groups: Registered
Joined: 11/22/2009(UTC)
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Two things, one old and one new:
- The old: I did indeed jumper around the Thermal Cutoff, and the dryer ran with heat. That's one reason why I felt good just replacing that part.
- The new: I put the jumper back in and ran the machine. The heat came on (as before), but this time I watched the heating element, and it was NOT cycling, even on the low/delicates setting. I watched it for about 5 minutes. Things were getting pretty toasty in there! In normal operation, the heating element should cycle on and off, right?
I take it that this means the Cycling Thermostat is not operating correctly, even though it showed continuity, and I should replace that component along with the Thermal Cutoff (and the Hi Limit Thermostat, while I'm in there). Am I correct, or am I missing something else here? Thanks again, Bob
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Rank: Advanced Member
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Did I screw up by NOT replacing the Hi Limit Thermostat?
Yes , well perhaps.
The fuse on the heater is a safety device. The hi-limit thermostat should control the temperature so that the fuse does not blow. Therefore if the fuse does blow the hi-limit is not regulating the temperature so it is assumed that it is toast. Note that the hi-limit is also just a safety device.
If the unit is running on the hi-limit, this indicates a problem as the hi-limit should not be regulating heater temperature, the cycling thermostat on the blower should be doing this.
You may have a grounded element (the element has sagged or broken and is touching the case) in which case none of the thermostats can regulate the temperature. Often you can see this by inspecting the heater assembly.
It can be checked with a meter.
Unplug the unit and remove the wires from the heater. Measure the heater should be around 10 ohms. Then measure from each connector to the case/frame both should be infinite ohms (open).
Another possibility is a restriction or leak in the air flow inside the unit.
The dryer is actually sucking air over the heating coils, through the drum and then pushing the air out the exhaust. If the lint filter is coated with fabric softener residue this can reduce the air flow significantly causing the heater to run hot.
Also the operating/cycling thermostat is on the blower wheel so if the unit is sucking in air through a blown seal, it sees a cooler temperature at the blower and again causes the heater to run hot.
Hope this helps.
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THIS FORUM IS DEAD!!!!!!! |
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Rank: Member
Groups: Registered
Joined: 11/22/2009(UTC)
Posts: 4
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Thanks, denman!
I think you hit the nail on the head with the inside airflow restriction idea. I thought I was getting good airflow throughout, because my lint screen was clean, and I was getting what I thought was normal flow at the outside of the vent duct. And when I ran the unit disconnected from the duct and the air just blasting into the laundry room, the flow was about the same. Well...
I pulled off the lint chute/blower cover, and found a HUGE wad of lint, sticks, paper clips, pencil stubs, and more lint crammed in right in front of the blower! :eek: It was the size of a couple fists (I was going to say A HUMAN BRAIN, but... :D ). After removing that, I cleaned out that whole chute, and put things back together. There did not seem to be anything obstructing the Cycling Thermostat and Thermal Fuse area.
I do indeed have an open circuit between either heater element connector and the heater case.
So... I fired the dryer up (still jumpered around the Thermal Cutoff), and things sure seemed to run normally: I have heat, the heater element cycles on and off, and there seems to be a proper response to the setpoint temperature (cotton vs perm press vs delicates).
Looks like I need to replace that blown Thermal Cutoff, and the HI LImit Thermostat while I'm there.
Thanks,
Bob
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Rank: Member
Groups: Registered
Joined: 11/22/2009(UTC)
Posts: 4
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I managed to find a local source of parts. So I picked up a Thermal Cutoff + Hi Limit Thermostat kit, went home, and installed them both this time.
After two full dryer loads, everything seems to be running just fine!
I'm calling this another case solved, with the help of the internet and random, but interested, strangers...
Thanks, everyone!
Bob
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