LG gas dryer: constantly tripping the manual-reset thermostat

[jemenake]

I recently bought a used LG DLG2532 dryer. The seller assured me that he never had any problems with it.

He had it configured for propane (and had lost the original NG orifice), so I had to order a new NG orifice, install it, and adjust the gas-control screw all the way out for NG.

Now... about 2/3 of the time, the manual-reset thermostat (part M230 in the service manual diagram... or LG part number #6931EL3003C) trips and the dryer won't heat anymore until I take the front off and reset the little button on it. I'd like to find out why this is happening.

The after-dryer ducting is about 10 feet of straight (non-corrugated) 4-inch steel, with a couple of steel adjustable elbows. According to the manuals, this is much shorter than the max duct length. Lint screen is clean (although the "check filter" light always blinks when I turn the dryer on)

I've got a Fluke infrared thermometer, and the side of the dryer does get pretty hot (I measured up to 144F at one point). Not sure if that's normal.

So, my questions are:
1 - What are some common causes of this? I know the impeller/fan is the last thing before the air leaves the dryer. If there's some air leakage between it and the flame funnel, could that cause there to be not enough air being drawn out of the funnel (like the extreme case when someone tests the dryer with the front off or door open)?
2 - There are two thermostats: One is a auto-resetting lower-temp one that is supposed to trip at 203F +_ 7F and the high-temp manual-reset one that's supposed to trip at 212F +_ 12F. It strikes me as a little odd that the lower-temp one isn't tripping first. Is it plausible that the higher-temp one has gone bad and is tripping at an abnormally-low temp? How would I test for this? Or, has the lower-temp thermostat failed because it's not tripping *before* the high-temp? Should the lower-temp thermostat be tripping as a part of the normal operation of the dryer (ie, is that the primary way that the temperature is controlled) or are the gas valve and orifice supposed to be calibrated to deliver the right amount of gas and neither thermostat should normally be tripping?

- Joe

DLG2532


High Limit Thermostat Part # 6931EL3003C

[RegUS_PatOff]

It could be a bad manual-reset Thermostat.
You could test it by putting it in a glass of warm water...heated to (or add cold water) to near 180F. It shouldn't open.

It may have gone bad from over-use tripping, maybe unknown to previous owner.

You could use a meat thermometer in the vent to test the temperature.

With any empty load, timed dry, high heat, it should cycle somewhere between 135F & 160F

I sounds like you already have the Service Manual ?

[jemenake]

It could be a bad manual-reset Thermostat.
You could test it by putting it in a glass of warm water...heated to (or add cold water) to near 180F. It shouldn't open.

I'd think that dunking a switch in water would be come with some kind of "make sure you let it dry out before putting it back in" disclaimer.

It may have gone bad from over-use tripping, maybe unknown to previous owner.

The manual-reset one? If it did, then he wouldn't get any heat until he reset the thermostat.

You could use a meat thermometer in the vent to test the temperature.

With any empty load, timed dry, high heat, it should cycle somewhere between 135F & 160F

I'll give that a try tonight...

I sounds like you already have the Service Manual ?

Yup.

[RegUS_PatOff]

... I'd think that dunking a switch in water would be come with some kind of "make sure you let it dry out before putting it back in" disclaimer...

...wasn't thinking... of course I would do that ...

...The manual-reset one? If it did, then he wouldn't get any heat until he reset the thermostat.

...hhhmmm.., unless he knew about it... we'll see...

[jemenake]

With any empty load, timed dry, high heat, it should cycle somewhere between 135F & 160F

Okay, the manual-reset thermostat tripped in a pot of water at about 207F. That's within the 212F +_ 12F in the service manual.

I hooked it back up but did *not* mount it back on the funnel so that I could do the timed-dry/high-heat test. The meat thermometer at the vent outlet on the back of the dryer showed the temp maxing out at about 175 and then dropping to about 135 before turning the heat back on again.

Bad automatic thermostat?

- Joe

[RegUS_PatOff]

175F may be OK...

is there plenty of air-flow ?

can you measure the temperature with the vent connected ?