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I have a Maytag dryer that had a vent hose blockage. Authorized Maytag repairman was called and to make a long story short. The entire vent hose has been replaced and tested for blockage, the bad heating element which had gone bad has been replaced and tested along with a bad thermo assy (ap4045859). Unit quit heating again. Repairman was called again, he replaced a faulty thermo assy (ap4045859. He made all necessary checks and said it would be Ok, just faulty thermo assy which he said they had been having trouble with. Unit quit again. Repairman called again another failed thermo assy (ap4045859). This time he replaced the thermo assy (ap4045859) and the thermister (ap4045224), and checked the internal heating temp which was 165 degrees and the outhside exhaust temperature which was 130 degrees. The vent run is a straight run approximately 15 feet long which has been used for approximately 5 years with this dryer and another 10 years with another dryer. No previous problems. Again the dryer has failed with another call to the repairman tomorrow. Any ideas!!!!
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On the blower you have 2 devices:
The thermistor
A thermostat safety (thermal fuse). It blows at 185 degrees F. It kills power to the motor.
On the heater you have 2 devices:
The hi-limit thermostat. It opens at 261 and re-closes at 210 degrees F.
A thermostat safety (thermal fuse). It blows at 320 degrees F. It kills power to the heating coil.
I cannot comment on the temperatures that were measured as I do not know where or how they were measured.
I can give some basic info.
The hi-limit should have prevented the heater's thermal fuse from blowing.
It is there to keep the heating coil from overheating and the thermal fuse is there as an additional protection.
So I would say that the hi-limit should be replaced.
It could be that it is sticking closed every once in a while and the fuse then blows.
You still have another problem as the hi-limit is just a safety device so you still have to find out why it is opening at all. It does sound like the unit is not controlling the temperature and the temperature is being controlled by the hi-limit.
Did the tech try to run on a lower heat setting to see if the dryer actually regulated the heat?
This could be a number of things.
Check for a grounded heating element.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on high and the heating relay on the control board cannot regulate it.
Check the internal seals in the air flow path in the unit. Your thermistor is on the blower, the exhaust is under pressure but the rest of the air flow path in the unit is under vacuum so can pull in room air. If this happens then the thermistor sees a lower than actual temperature and will keep the heating coil on.
Unplug the unit and check that the heating relay contacts on the control board are open. Could be they are welded shut so do not regulate the heat.
If all the above are OK then I would say that the control board is shot. |
THIS FORUM IS DEAD!!!!!!! |
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Rank: Member
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Joined: 12/21/2011(UTC)
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Thankyou, Denman for your reply. I'm on my way to see the repair shop owner. I appreciate your lengthy, very professionable/knowledgeable
reply. I will be in further contact. dalekmaidens
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Rank: Member
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Joined: 12/21/2011(UTC)
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Thanks again for your assistance, the repair shop is going to provide a loaner and take the unit to the shop.
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