Electric clothes dryer question - PeachParts Mercedes-Benz Forum

kerry · #1 01-04-2011, 12:59 PM

My wife says the electric dryer is not working as well as it used to. It's turning and appears to be blowing fine. With the dryer running and the door open I get a reading of about 400 degrees max at the inlet of the hot air. This temperature seems to be the same whether it is set on permanent press or cotton. Anyone know if 400 degrees is a hot enough temperature for the air inlet and whether the temperature should be different on cotton and permanent press. I'm wondering if there is a cut off switch which shuts off the heat at different temperatures on cotton and permanent press.
Basically, I'm wondering if I need a new heating element.

#2 01-04-2011, 01:11 PM

I don't know the temperature, but I would check the vent and make sure it's not clogged with lint first.

mgburg · #3 01-04-2011, 01:21 PM

Exactly! Most clothes dryer fires start because of restricted vents. Go down to a Dollar General and look for a "Lint Kit" - one of those brushes on a roto-rooter wire (about 10'-15' in length).

Pop the pipping off the back of the dryer and loosen it (carefully) from the vent pipping going through the wall and outside, then take the whole shootin' match out to the back yard and run the brush through the tube a few times. If you never have done this, it will shock you how much crap is actually stuck in that thing. Then, check the outlet pipe on the back of the dryer ( UNPLUG THIS THING BEFORE YOU START STICKING YOUR HANDS OR ANYTHING INTO ANY OPENING!!! ) and the vent tube and back-draft flapper outside. Yep, those things can clog up just as bad (or worse) than the tube itself.

Everything FINALLY clear? Put it all back together...plug in the dryer and run a load of wet through it.

It will amaze you how fast and dry your stuff will get NOW!!!

kerry · #4 01-04-2011, 01:28 PM

Vent is clear.

kerry · #5 01-04-2011, 01:41 PM

Ok, holding the door open and the safety switch closed, I may have observed the problem. I can see the heating element heat up and then cut out on different heat settings so the element seems to be ok. I'm now hypothesizing that the thermostat that controls the heating element is not working correctly. It does not seem to be getting very hot in the dryer and when the element turns on for the second or third time it only gets hot for about 10 seconds or less before the thermostat shuts it off again.
Where is this thermostat? Is it a failure item? How difficult is it to change it out?

lutzTD · #6 01-04-2011, 01:45 PM

first, not sure what model you have but with the door open you are interupting the flow path so be careful you dont burn up your element.

next, I would take off the front panel and look for lint inside. many dryers have issue with lint trapped inside the dryer. residential Maytags are some of the worst

lutzTD · #7 01-04-2011, 01:47 PM

Quote:

Originally Posted by kerry

Ok, holding the door open and the safety switch closed, I may have observed the problem. I can see the heating element heat up and then cut out on different heat settings so the element seems to be ok. I'm now hypothesizing that the thermostat that controls the heating element is not working correctly. It does not seem to be getting very hot in the dryer and when the element turns on for the second or third time it only gets hot for about 10 seconds or less before the thermostat shuts it off again.
Where is this thermostat? Is it a failure item? How difficult is it to change it out?

not a valid test, you are not passing air over the element with the door open so it is overtemping and shutting off

Stoney · #8 01-04-2011, 01:52 PM

On my gas dryer there were a pair of coils that controlled the ignition and the symptum you describe is similar.

Google the make/model number and there will be a site with a blog covering many makes and issues. Then you can go to all parts pro or the linke and order it. But if the repair involves removing the drum, get a pro because if you screw up the drive belt system it will never stop squeaking....ever.

Quote:

Originally Posted by kerry

Ok, holding the door open and the safety switch closed, I may have observed the problem. I can see the heating element heat up and then cut out on different heat settings so the element seems to be ok. I'm now hypothesizing that the thermostat that controls the heating element is not working correctly. It does not seem to be getting very hot in the dryer and when the element turns on for the second or third time it only gets hot for about 10 seconds or less before the thermostat shuts it off again.
Where is this thermostat? Is it a failure item? How difficult is it to change it out?

kerry · #9 01-04-2011, 01:53 PM

Quote:

Originally Posted by lutzTD

not a valid test, you are not passing air over the element with the door open so it is overtemping and shutting off

Ok, back to square one.

lutzTD · #10 01-04-2011, 02:00 PM

Quote:

Originally Posted by kerry

Ok, back to square one.

the most likely cause from my past experience is lint that is collected under the lint trap inside the dryer. the path is this:

intake inside unit
through heater
through drum
through lint trap
through blower motor
through internal pipe
through external exhaust

lint will be in the passage after the lint trap and before the blower. you cant reach that through the pipe in the back, you will need to remove the front panel

this can catch fire if you run the dryer too long with alreadt dry clothes as this will allow the temperature to climb quite high in the system

kerry · #11 01-04-2011, 02:06 PM

Measuring the plastic vent temperatures when it is running, it varies from about a low of 98F to a high of 121f. I can detect the heating element cycling on and off. I couldn't detect any difference in the vent temperatures (apart from the variation when the element was on/off) between the cotton and permanent press setting.

mgburg · #12 01-04-2011, 02:10 PM

Kerry:

On the few dryers I've fixed over the years, you'll find a "transistor" style item, usually, on the O/P side of the tube that the heating elements are mounted in/on. IF the temperature gets too hot...the "thermistor" (the "transistor" thingie) will open up and shut down the elements. After it cools down, it will reset and energize the elements again...until, of course, the "thermistor," again, heats up too much.

If the thermistor is bad (never resets/is open)...don't just substitute or bypass it. You'll burn up the dryer and everything around it. Get the proper part and only the proper part.

Otherwise...mother nature and a clothes line.

kerry · #13 01-04-2011, 02:10 PM

When I put my hand in front of the vent pipe outside the house, it seems to be pushing a high volume of air, no less than it ever did. The temperatures in the drum seem low not high. I can't recall sticking my arm inside this dryer and sensing the temperature before but I know it is WAY lower than the temperature inside the commercial dryers in a laundromat where you can barely hold on to the clothes when it shuts down and you can't touch the metal of the drum. The drum is warm in my dryer but not hot.

kerry · #14 01-04-2011, 02:13 PM

Quote:

Originally Posted by mgburg

Kerry:

On the few dryers I've fixed over the years, you'll find a "transistor" style item, usually, on the O/P side of the tube that the heating elements are mounted in/on. IF the temperature gets too hot...the "thermistor" (the "transistor" thingie) will open up and shut down the elements. After it cools down, it will reset and energize the elements again...until, of course, the "thermistor," again, heats up too much.

If the thermistor is bad (never resets/is open)...don't just substitute or bypass it. You'll burn up the dryer and everything around it. Get the proper part and only the proper part.

Otherwise...mother nature and a clothes line.

I think that's working. According to Lutz, that's what is cutting out the heating element after a few seconds when I have the door open.
I'm wondering if the control thermostat is not working correctly, not letting the dryer get hot enough.

lutzTD · #15 01-04-2011, 02:17 PM

Quote:

Originally Posted by kerry

I think that's working. According to Lutz, that's what is cutting out the heating element after a few seconds when I have the door open.
I'm wondering if the control thermostat is not working correctly, not letting the dryer get hot enough.

whats the maker and model of your dryer? my money is still on built up lint