Author Topic: Roper dryer getting to hot  (Read 190 times)

Offline Repairit

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Roper dryer getting to hot
« on: September 12, 2014, 08:41:11 AM »
Hello everybody! I have a client that has a roper dryer Model # RED4100SQ0 that wouldn't heat. Yesterday I diagnosed a faulty heating element and replaced the element as well as cleaned all internal ductwork, check the external venting, checked the two fuses, as well as well as the two thermostats, which ohmed below 1 ohm. When I started the dryer I noticed that the element was getting very hot, so I went ahead and replaced the element thermostat and cutoff fuse. This morning I got a call from the same client that the dryer now will not start, so I'm pretty sure it blew the thermal limiter on the blower housing. Any ideas on why the heater is getting so hot and not cycling? I'm leaning towards the blower housing thermostat but it ohmed properly... Any help is greatly appreciated!

Offline fairbank56

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Re: Roper dryer getting to hot
« Reply #1 on: September 12, 2014, 01:36:05 PM »

  There is only one fuse and that's the thermal fuse on the blower housing. It is in the motor circuit, not the heat circuit. The device at top of heater box is a thermal cutoff and the device at bottom of heater box is the hi limit thermostat. So yes, it now sounds like the thermal fuse has blown. The hi limit and thermal cutoff don't regulate the heat, they are only safety devices. If it gets too hot in the heater box, the hi limit should start cycling the heat coil and if that fails, the thermal cutoff will trip and kill  power to the heat coil permanently. The operating thermostat on the blower housing is what regulates the heat. So, I'd say you either have a faulty operating thermostat or an air flow problem. Air flow problem can be caused by excess lint buildup in the internal/external duct, faulty seals at drum or blower housing causing leaks or the blower wheel slipping on motor shaft. If the air flow at exhaust on back of dryer seems sufficient, then looks like the operating thermostat is not opening at the proper temperature or is stuck closed and not opening at all. It can be checked on a hot plate.

Eric

Offline keithvibe

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Re: Roper dryer getting to hot
« Reply #2 on: September 12, 2014, 06:55:49 PM »
when you say it was getting very hot... did you get an actual temp reading? If so did you check it with the temp on the thermostat? Did you check the rating on the old one? maybe the wrong one? Possible bad one.

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #3 on: September 12, 2014, 07:18:20 PM »
Thanks for your input guys... Found a faulty timer!

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #4 on: September 12, 2014, 07:21:45 PM »
And yes it got hotter than thermostat rafting... It was climbing in the 400 degree range, which I don't understand why one of the fuses didn't blow!

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #5 on: September 12, 2014, 07:22:52 PM »
*rating

Offline fairbank56

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Re: Roper dryer getting to hot
« Reply #6 on: September 12, 2014, 07:25:02 PM »

  Well, a faulty timer can prevent the dryer from starting but it can't cause it to overheat.

Eric

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #7 on: September 12, 2014, 07:53:40 PM »
Don't know.. I found all the contacts closed in the high heat mode. Before I tested the timer I made sure that the thermostats were reading under 1 ohm (actually reading .03 ohms) and also that the element wasn't grounded. I condemned the unit and gave the customer the cost back for the parts.

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #8 on: September 12, 2014, 07:55:53 PM »
The dryer had gotten so hot that the door switch melted... Still can't comprehend on why one one the fuses didn't blow.

Offline fairbank56

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Re: Roper dryer getting to hot
« Reply #9 on: September 12, 2014, 08:23:04 PM »
I found all the contacts closed in the high heat mode.

  If all the timer contacts are closed, it's in low heat mode but the timer doesn't really regulate the heat directly, it either turns the thermostat heater off for high heat or applies power to the thermostat heater for the low heat setting. It's the operating thermostat that ultimately controls the on/off cycling of the heat coil and thus the dryer exhaust temperature. Just because the thermostat reads less than 1 ohm doesn't mean it's good. If it doesn't open at rated temperature, it's faulty. Sounds like multiple component failure if heat was getting to 400.

Eric

Offline Repairit

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Re: Roper dryer getting to hot
« Reply #10 on: September 13, 2014, 12:55:42 PM »
Thanks fairbank56 & keithvibe for you all's help... Great info fairbank56! :thanks:

Offline Maytag Man 6725

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Re: Roper dryer getting to hot
« Reply #11 on: September 13, 2014, 05:38:01 PM »
Make sure your new element isn't grounded!

 

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