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Hello,
What would cause the thermal cut off fuse to blow.
I have found no restriction with the air flow and after replacing both the high limit thermostat and the thermal cur off fuse, the thermal has blown for the second time.
Any insight would be greatly appreciated.
Thank you.
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Rank: Member
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Hi denman,
It is the the third part in the list that has blown.
Thanks
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Rank: Advanced Member
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You may have a grounded element.
Since the thermal cut-off has blown twice, you have to find out what caused it to go.
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 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 thermostats cannot regulate it so the thermal cut-off blows.
You have already replaced the hi-limit thermostat so I am sort of betting on the grounded element theory.
The hi-limit should have regulated the temperature so the fuse did not blow.
Note: That unless there is another problem in the unit the hi-limit should never have to open. It is just a safety device with the fuse being a backup safety device.
Just in case it is not a grounded element.
With all the below the high limit will also have to be replaced.
Check that the belt is OK.
Check the seals (drum etc) in the unit. The air is pulled over the heating coils, through the drum and pushed out the exhaust. So any large seal leak will pull in room air and the cycling thermostat on the blower will run the unit hot.
Check that the lint filter is not coated with fabric softener residue which greatly reduces air flow.
Check/clean your vent system.
Check/clean the blower wheel.
If all OK you may want to replace the cycling thermostat as it's contacts may not be opening (welded shut). |
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Hi denman,
Thank you for the excellent information.
I will check what you have suggested.
Have a great day.
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Rank: Member
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Hi denman,
Unless I have missed something, all that you suggested tests okay.
Would the cycling thermostat still test okay if it had welded itself shut?
Thank you for your help.
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Yes it will measure 0 ohms.
The only way I know how to test it is to put it on a stove element or heat the face up with a soldering gun. The problem is that there is no reliable way to know at what temperature it is opening if if does. |
THIS FORUM IS DEAD!!!!!!! |
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Rank: Member
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Thank you denman.
I will give it a try.
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