Defrost Control Board Wiring Diagram

[Ene Vinson]

Im also having a defrost issue with this model. Marcone shows the control board W11321510 to be replaced by W11566851. So, I ordered the updated part number and that's what shows on the box. However, the board inside is the older part number but with a different revision letter than what's already on the refrigerator. Any insight as to whether those revision letters mean anything?

Does anyone have anything else to add on this refrigerator model with defrost problems? I've been called to check this refrigerator for the third time with the same problem....evap freezing over. All components test ok. Replaced the control board and defrost thermistor anyway. I even ziptied it directly to the suction line without the plastic clip. Door seals are in great shape and sealing correctly.

Did you check defrost heater molex connectors? Especially the one with Green&Black harness. I had service call today for model WRS315SNHM06 with exact same issue. During the Forced defrost cycle, I noticed it was not drawing any amps, as soon I touched that green&black harness, amps started drawing.

In my case, I was not able to figure out what was causing the machine to freeze up or not initiate the defrost cycle. I could command defrost in the diagnostic mode and the heater would operate fine. Give it a week or so and the evap coils would be full of ice.

Is it not going through defrost at all if not you need to check the over temp cut outs for continuity. If it got too hot from over defrost it'll open those up. Even before you do that you should put it in diagnostics and see if it'll run the defrost heater while it's in diagnostics. If not check Loz power to element and if getting power then you should be able to test the over temp cut outs. You can also check in diagnostics if the thermistor/DF sensor on the evaporator is closed while it's frosted over.

Depending on which model thermostat you have, it is actually correct that the auxiliary heat is typically wired to the W2/AUX terminal. The real question is, did the technician make changes at the air handler or the outdoor unit at the same time? I asked this question because in a heat pump system, it is the outdoor defrost control board that initiates the auxiliary heat. Between the outdoor heat pump unit, and the indoor air handler, the defrost control board has a W2 terminal that is connected to the W2 terminal in the air handler. A dual fuel system would typically be a heat pump with a gas or oil fired furnace. You employed a workaround when you had it wired as a dual fuel system and the temperature cut over at 40F.

The tech did do something in the air handler. But just to clarify, I have a Nest Learning thermostat (3rd gen), a heat pump, and heat strips in the air handler. The Nest wiring diagram currently shows a white wire into W1. Should it instead be in W2?

GL4, the way heat pumps work between the defrost control board and the indoor air handler is that the defrost control board uses a W2 signaling wire to activate the electric heat in the air handler. Typically a thermostat is wired to the very same auxiliary heat unit using an E wire to enable the homeowner to activate the emergency heat in the case of a failure of the outdoor unit. As for auxiliary heat, when activated by the outdoor unit, the signal wire sends a signal to the thermostat on W2 to allow the thermostat to know that auxiliary heat has been turned on. In some cases, smart thermostats can be programmed in such a way that if it detects that the heat pump is running, and the outdoor ambient temperature is so low that the heat pump cannot keep up with the demand for heat, the thermostat can also activate the auxiliary heat to boost the heating capacity of the system. The nest is one of these types of advanced thermostats.

The goal here is for you to, that is, if you are comfortable, to ensure that your thermostat has the white wire on W2/AUX and in the air handler, the same color wire is also on the W2 of the control board. Do you have access to the indoor Air Handler?

If he indeed connected all three stages together then it should work. The problem is if the control board has indeed 3-stages of heat, and if the air handler does not have 3-stages of heat, it can act erratically. You should not tie W1, W2 and W3 together in the air handler. For me to look up the control system, I need the model number of the air handler. Some systems have multiple banks of heating strips and get activated is a sequence or as Stage 1 and Stage 2.

Sometimes the installer uses differ colored wires instead following industry standards. What ever color is in W2 should be in W2 at the other end. Your Trane air handler can indeed have up to 3 stages of electric heating coils. In order for that to be the case, separate electrical contactors are used for each stage. Additionally, you air handler has an Elecyriclly Commuted Motor (ECM) and can greatly vary the speed of the blower. Can you get me the model number of the outdoor unit?

Your outdoor unit is a single stage Heat Pump. Not sure how many stages of electric heat you have in the indoor air handler unit. The auxiliary heat kits are installed by the contractor and not by the factory. Since the outdoor unit does contain an outdoor temperature sensor, the connection between W1 and W2 and W3 is not a valid configuration. The proper configuration between the Nest thermostat, the air handler and the outdoor unit typically W1 from the thermostat to W1 in the air handler, W1 from air handler to W1 on the outdoor heat pump, W2 from the outdoor heat pump temperature sensor W2 going to the air handler W2 to the W2 of the thermostat.

The AC Cooling Wizard

The Nest App just uses different colors to simply differentiate the wires. What matter is what color wire is in the terminal backplate and the other end. If you think about it, the thermostat is not smart enough to see the color of the wire. So, the software uses the industry standard wire colors for each terminal.

Unplugged the fridge and let it sit overnight with towels in the bottom to capture excess moisture. There was still some ice at the bottom of the evaporator, so used a hair dryer on the lowest heat setting to get rid of it.

The wiring diagram for this model says that the unit has an electronic defrost control. The procedure to invoke a manual defrost is to operate the light switch on the fridge side 5 times within 6 seconds. I did that but do not see any signs of defrost action. I'm using both a non-contact AC probe (Fluke LVD2) and checking at the defrost heater as well as the defrost termination temp snap switch clipped to the top tube of the evaporator. Tried this several times.

The evap coil is currently sitting at about -43C and is accumulating ice. I'm leaning towards suspecting the refrigerator control board but would greatly appreciate advice on other things I can check.

Problem turned out to be the "Adaptive Defrost Control" module. There are two electrolytic caps on the board. The larger of the two (1000uF / 10V) had the classic bulged top. I replaced that capacitor and checked both the value and ESR of the other capacitor (22uF / 100V) - seems to be okay. I would have replaced it as well but that isn't a value that we stock. But it seems okay.

Answer Steven, With the control board having already been replaced and the unit defrosting in the diagnostic mode, this would most likely be an issue with the thermistor. Even though it is passing in diagnostics there could be a problem with it.

Answer Hello Rodney, there is also a cold control thermostat WP2198202 that controls overall operation. To test if its the thermostat or the defrost board, the next time it stalls in defrost, unplug the ref from the outlet for a few seconds then back in, if it restarts its the defrost board, if it does not restart, turn the thermostat knob off/on and it restarts then its the cold control thermostat.

Answer It sounds like you could have an issue at the main control. Find your tech sheet and wiring diagram and find where the voltage comes from to the auger motor the main control or dispenser control? If the main control powers auger, check the wiring from dispenser control to main control and from control to auger. Wiring at the door hinge could be an issue to look for as well.

Answer Hello Bob,there are two controls that power the compressor/fans, the defrost board and the cold control thermostat, a failure of either will stop the cooling. The cold control thermostat can be tested with a multimeter for continuity in the run position. The defrost control should have 120v went tested at terminals P5 orange to P4 white.

Answer Hello Jim,the led light modules in the freezer and fresh food sections are powered strictly through the door switches. The lights are wired in series, if one is faulty it will affect the other two also. If all the lights are flickering when either door is opened then it is usually a faulty/failing freezer light module part W11104452.

Answer Hello Kevin,the defrost control board does not control the lighting, the led light module in the freezer is faulty, and is causing the fresh food lights to dim as they are on a series circuit, the freezer led light module is part WPW10515057.

the Defrost Control Board Is An Oem Replacement Part for Whirlpool Refrigerators. This Circuit Board Coordinates Defrost Heating Cycles to Remove Built-Up Frost From Evaporator Coils.

causes Relate to Water Damage Following Leaks, Component Failure Due to Power Surges Loosening Connectors, or General Component Wear Over Time.

symptoms of Issues Include:

Maybe check if the drain tube under the evap unit is OK and not blocked, preventing the defrost meltwater from fully draining away, so that it refreezes and eventually builds up covering the fan and the evap unit.

The tech sheet wiring diagram shows a thermal fuse in the heater circuit. I realize that you said that the heater is working so the thermal fuse must be OK Looking at the parts list (see below), the thermal fuse is part of the evap fan harness cable and it is there as a safeguard to prevent the evaporator unit getting too hot during a defrost cycle.

3a8082e126