Reefer runs for 45min of each hour. Freezer seems to stay relatively cold although at times ice cream is somewhat soft. Condenser coils, back, and front have been vacuumed after gently blowing out dust. Reefer temp. seems normal. Shouldn't a bad thermostat (temp control unit) cause more of a temperature issue in the freezer? Should I replace the temp control unit?.
Answer Hi. Look at the back wall of the freezer to see if it is frozen over and you see frost build up. If so then you have a normal defrost issue. This leads to a NO-COOL. The defrost control part # WR9X520 stops the compressor run time and sends the voltage to the defrost thermostat every 6-8 hrs depending on the model. If the defrost thermostat senses the frozen temperatures in the evaporator/freezer area it closes and it sends the voltage to the defrost heater part # WR51X466 to defrost the evaporator coils. When the defrost thermostat part # WR50X10010 senses the heat inside the area has risen to 45° it opens and stops the heater voltage for safety limits not to melt the cabinet. Use a volt/ohm meter part # TJMA-DM1 to assist you in your diagnostics. Find the tech sheet inside the controls and it will allow you to put the unit into a self diagnostic mode to start the defrost. Follow the wiring diagram to check the voltage on the pin/wire output to the heater circuit. See if the defrost control is at fault. 75% of the time its a combination of this and the defrost thermostat not closing in frozen temperatures. Use the ohm meter and remove the wires off the thermostat and check to see if It is closed (O-ohms) at frozen state. Use towels to catch the defrosted water as you pour hot water on the coils and defrost them manually. Block the drain pan to catch the water with the towels or use a hair dryer to melt the ice on the evaporator. Then the unit will return to normal as the lightly (normal) frosted coils allow the evap. fan to circulate the cold air through the damper into the fresh food area once again. The cold control, part # WR9X517 will sense a satisfied temperature and shut the compressor off. Thank You.