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Maytag Dehumidifier Compressor Does Not Run

Jeffceo

Premium Member
Joined
Dec 27, 2011
Messages
20
Location
CT
Model Number
M3DH30B2A
Brand
Maytag
Age
6-10 years
Hello,

I have a Maytag M3DH30B2A Dehumidifier (portable). I typically use it downstairs in the summer but we have a lot of moisture in the garage from recent winter weather so I set it up in the garage. It turned on and the compressor came on. I came back a short while later and the fan was running but the compressor had stopped. I tried a different outlet in case the outlet it was in did not have adequate amps; same deal. The fan turns on but the compressor does not start. I thought it may be too cold in the garage (45) and the cold temp made the frost sensor kick in. I brought it inside the house to warm up for a few hours and still the same thing. I took it apart and checked for lose wires, overheating compressor, etc. I tested the voltage from a red wire going to the compressor and each of the two wires coming off the capacitor. 119 on both. I thought the capacitor could be bad so I swapped it out with a brand new one with the same specs (15UF 370VAC capacitor 50/60hz). No difference. The unit itself is in good condition and has minimal use. Any ideas where to look next?

Thank You
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
44,797
Location
Murray, Utah 84107, United States
It's not actually part of any HVAC and it's not a major appliance so service schematics probably don't exist. Here's what I can tell you; There are two wires supplying voltage to the compressor via a start device. The start device might consist of an overload and relay (and capacitor) or it might be an enclosed unit containing the relay and overload that pulls off the compressor. Measure the voltage between the two wires on the relay/overload/start device. If the voltage is 120 VAC, unplug the machine and remove the relay/overload/start device from the compressor. It pulls straight off the three compressor pins/terminals. Set your meter to read ohms on the lowest scale (RX1) and measure the compressor start windings (C to S). You should have between 3-11 ohms. Then measure the run windings (C to R). You should have 1-5 ohms. Then measure between each compressor terminal and the compressor body. Your meter should show infinite resistance. If the compressor measurements are correct you might have a faulty start device. Since that unit and most of it's parts have been discontinued, you'll need to post a picture of it for me to find the correct part.
Compressor Config.jpg
 
Last edited:

Jeffceo

Premium Member
Joined
Dec 27, 2011
Messages
20
Location
CT
Thank you for the help. That is some great info. There is a plastic cap on top of the compressor with the letters C S R. Underneath there is a small round plastic part with a spring on it. I would imagine this is the overload device. I did some more troubleshooting last night before I saw your post and discovered there is some type of sensor inline with the red wire going to the compressor, this wire does not go through the capacitor. The "sensor" is clipped on to one of the coolant/refrigerant lines. I disconnected it and tested the resistance; it was open. I tapped it in case there was a stuck switch inside, no difference. I used a jumper wire to bypass this sensor and the compressor ran. There is a number on the part: 37TA32 501624 F57-20F J0413. Not 100% sure on the last 4 digits as they are obstructed. Inside the white plastic cap is filled with resin/epoxy. Please see the pictures. Is is safe to bypass this?
photo (1).jpgphoto (2).jpg
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
44,797
Location
Murray, Utah 84107, United States
That part is the thermostat for the compressor. It's a normally closed thermostat that opens at 57*F or below. It works just the opposite of a defrost thermostat on a refrigerator. Unfortunately, if you bypass it the compressor won't shut off. None of those numbers are part numbers and so far I haven't been able to locate one either.
 
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