Thermostat, Defrost

Mtbob

Answer You can test the defrost heater and defrost thermostat with a multi-meter. Both of these should read closed or 0 for continuity. If one is open, then that is your bad part. If both are closed then you have a bad timer. 

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JIMJESSE699 for Model Number magic chef fridge ctb1925grq

Answer Hello JimJesse699 It sounds like the thermostat 61005789 on unit is faulty and would need to be replaced. 

Tom for Model Number crosley ct15a2w

Answer Tom, Temperature has nothing to do with the voltage. There should be 120 VAC into and through the entire circuit. (unless the defrost thermostat is an open circuit, due to it being warm). There should be 120 VAC into the thermostat on the blue wire, out of the thermostat on the white wire, into the heater, through the heater and at the yellow wire out of the heater to the defrost timer, as long as the temperature control is a "closed" circuit and the refrigerator is cooling. With the voltages you posted, there's a loose connection or damaged wire in the harness. The neutral portion of the circuit is accomplished through the yellow wire(terminal 2) and white wire(terminal 1). Do all of the voltage checks to chassis ground, on all the connections, this will verify wether you have a loose connection, or and issue in the neutral circuit at the timer. Thanks 

Dan for Model Number MTB2156DEQ

Answer Hello Dan. If the thermostat 61005254 is not closed and passing voltage to the heater, yes it is bad and needs to be replaced in the unit. 

Mike for Model Number atb2135hw

Answer Hello Mike, There are only three components in the defrost circuit not counting the wiring harness. On this model, I would say you probably have either a bad defrost heater or a bad defrost thermostat. The defrost timer is the other component. You can use the defrost timer to assist you in the diagnosis. If you look straight up at the control box, (ceiling of the fresh food compartment), yo should see a hole that has a large plastic screw looking device in it. If you use a small screwdriver in this hole and turn it clockwise, you will hear it clicking as you turn it. It will then make a loud click. If you stop at this point, you have forced the unit into defrost. This will put voltage to the defrost thermostat. Testing at the defrost thermostat, you should read 120Vac on both sides of the device. If not, the defrost thermostat is at fault. If so, the defrost heater is open. If there is no voltage on either side of the defrost thermostat, the points in the defrost timer are at fault. Once you have found the device at fault, you can go ahead and defrost the unit with a hair dryer. This will cause the unit to cool properly for about 5 to 7 days normally while you wait on the part. When you receive the part and put it in, you will need to defrost the unit again because the defrost cycle can only melt away the amount of frost build-up between normal defrost cycles. Not defrosting the unit will cause an air circulation deficiency that you will most likely notice in you milk, (milk will spoil quicker than normal without the unit cooling at full efficiency). 

Dan for Model Number MTB2156DEQ

Answer Dan, With the defrost timer in the defrost mode, you should read 120 VAC from blue(#3) to white (#1) this is power in, and from yellow(#2) to white(#1) this is power out, to the heater 120 VAC. The defrost thermostat, should have a closed circuit below 38 dgrs.F. and an open circuit above 38 dgrs. ( put the thermostat in a glass of ice water for a few minutes then check the circuit). The heater element should have a resistance reading(approximately 20 to 30 ohms, on that unit), it sounds more like a defrost timer issue, based on your post.