GE electric dryer thermostat replacement

DANGER: If you make a mistake while working on your dryer, you will die. DANGER: Hazardous voltage. Contact will cause electric shock, burn, or death. Most household electric dryer circuits can deliver over 30 amperes at 240 volts AC. DISCLAIMER These photos and descriptions are provided for information only. Do not attempt. This Web page is NOT created by, sponsored by, endorsed by, affiliated with, or otherwise connected to General Electric Inc., Therm-O-Disc, or Emerson Electric Co. The creator of this Web page, other than owning GE appliances, has NO CONNECTION with General Electric Inc., Therm-O-Disc, or Emerson Electric Co. The thermostat shown here is for one specific model of GE dryer. The parts for other models and makes will vary.

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A relative has a GE electric clothes dryer, model DBXR463ED2WW, from circa 2005. It ran well when first installed, but had later developed long drying times. Sometimes, in the automatic cycles, it would shut itself off before the cycle completed.

I cleaned lint out of the vent duct, and reworked the duct once (adding formed sheet metal elbows, instead of just bending the duct 90 degrees). I was told that these efforts helped a little, but the long drying times still happened.

Recently, I was able to spend some more time on it. First, still thinking it was a venting problem, I reworked the duct again, replacing the flexible duct with a combination of straight sheet metal duct and a different flexible duct - no change. I then disassembled the dryer, hoping to find a sock or big lint wad somewhere in the air system. I pulled a little bit of lint out, but this didn't change the situation much. The service sheet inside the control console gave a spec of 47 to 51 RPM for the drum; I checked with a stopwatch and it was right at 51 RPM. I measured the line voltage at the dryer; it was about 238 V with the dryer off and 236 V with it running on high heat, so that seemed OK.

I reassembled it and ran a load of laundry the automatic cycle - the dryer again shut itself off before the cycle completed. A friend happened to touch the flat top of the dryer and commented that it was really hot. I checked it and agreed; it should be "warm" in operation, but no so hot that you can't stand to put your hand on it for more than a few seconds. I let the dryer cool off and complete that load.

Looking at the service sheet, the only thermostats that could stop the cycle like this are the high-limit thermostat and the overload protector on the main motor.

I then ran another load, and when the dryer shut itself off again, I unplugged it, opened up the control console, and verified that the "high limit" safety thermostat (which opens at 315° +/- 10° F or 157° +/- 6° C) was open. (Both wires for the high limit thermostat appear in the control console, unlike the three other thermostats in the dryer.)

I figured that one of the other thermostats in the dryer was not operating correctly, so I decided to test all four of them for opening and closing temperatures.

1. The high-limit thermostat lives on the "pizza pan" that the heating elements are mounted to. It shouldn't open up unless there is a problem. If it opens up, it breaks the circuit to the "run" winding of the main motor. As the main motor slows down, the centrifugal switch on the main motor will break the circuit to the heating elements.

2. The safety thermostat also lives on the "pizza pan". It shouldn't open up unless there is a problem. If it opens up, it breaks the circuit to both heating elements.

3. The control inlet thermostat also lives on the "pizza pan". It opens and closes as the dryer runs normally. It controls the circuit to one of the heating elements. In the "automatic" cycles, it also does not allow the timer motor to run until the thermostat opens. This thermostat also has a small internal heater, which is energized in certain cycles to make the thermostat open at a lower temperature.

4. The drum outlet thermostat lives on the blower housing, downstream of the blower. It opens and closes as the dryer runs normally. It controls the circuit to both heating elements. This thermostat also has a small internal heater, which is energized in certain cycles to make the thermostat open at a lower temperature.

To test each thermostat, I connected a multi-meter in "continuity buzzer" mode across the terminals of the thermostat. I held a thermistor temperature probe against the base of the thermostat to monitor the temperature. I then heated the thermostat until it opened, noted the opening temperature, and then let it cool and noted the closing temperature.

I got this test procedure from the document Bimetal Disc Thermostat Application Notes from Therm-O-Disc / Emerson Electric. Therm-O-Disc manufactured all four of the thermostats I had.

The drum outlet thermostat is supposed to open at 135° +/- 5° F. To test it, I held it over a 75 W incandescent lamp. The other three thermostats open at 210° F or above, so I tested them with a heat gun.

I debated about whether I needed to energize the internal heaters for the two thermostats that had them, but I decided against it. The 69T Product Bulletin implied that the thermostat ratings assume that the internal heater is not being used. It would also be simpler and safer to test the thermostats without using the internal heaters.

I found that three of the thermostats switched at temperatures fairly close to their nominal values. The switching points did change by a few degrees F if the thermostat was starting from cold (after sitting on a 65° F concrete floor for 30 minutes or more) versus having recently been heated and cooled.

The control inlet thermostat still switched, but it did so far outside of its nominal switching points.

I decided to replace the control inlet thermostat.

Several online parts sites listed it as GE part number WE4M181 and sold it for prices $29 to $49 including tax (if applicable) and shipping. I checked a few local distributors and found one in stock; it cost me $39 with tax.

The replacement thermostat was slightly different than the original; on the original, the mounting feet are rotated 45 degrees from the main terminals, while on the replacement, the mounting feet are rotated 90 degrees from the main terminals. I was concerned about the thermostat body hitting the drum when installed, but it turns out that the replacement part fits OK.

I reassembled the dryer and first verified that it ran on the "no heat" setting. I then dried large loads of laundry on all three heat settings, using the appropriate "automatic" cycle for each load - the dryer ran normally and did not shut off until the cycle was complete. I sat near the dryer for each of these cycles to catch any overheating or other misbehavior - very exciting.

	Top view of the old (failed) thermostat. Note the mounting feet at 45 degrees to the main terminals.
	Side view of the old (failed) thermostat.
	Top view of the new (replacement) thermostat. Note the mounting feet at 90 degrees to the main terminals.
	Side view of the new (replacement) thermostat.