Brand:Whirlpool
Model Number:WRF555SDHV00
Main Symptom:coils frosting on back bottom.
What happens & when:Runs for about 2 weeks then frosts again
Error Code (if any):
Parts or tests already tried: Defrost thermostat OK, heater had 40ohms replaced control board
Photos / video link:
WRF555SDHV00 Refrigerator Tech Sheet - W11050317 - Rev B.pdf (263.8 KB)
Do this test and change it to the Basic mode Service Test - 7 Defrost mode
The defrost mode can be set by using SW3. In ADC Mode the product will automatically defrost after a minimum of
8 hours of compressor runtime up to maximum of 96 hours of compressor runtime, depending upon product usage. In
Basic Mode the product will automatically defrost after 8 hours of compressor runtime.
(01 = ADC ON, 02 = Basic Mode ON) 8 hour timer. Also check your Thermistors.There should be a thermistor mounted to the Evaporator.That one should be tested with a meter as it could be out of range as related to ohms at a certain temperature!
For your Whirlpool refrigerator model WRF555SDHV00, the fact that frost builds up on the back bottom of the freezer about every two weeks strongly suggests a defrost problem.
Since you’ve already checked the defrost thermostat, measured approximately 40 ohms through the heater, and replaced the main control board, I wouldn’t recommend replacing any more parts just yet.
The next step is to determine whether the defrost heater is actually receiving power during a defrost cycle.
Remove the freezer’s rear interior panel and look at the evaporator coils.
If the entire evaporator is frosting over, continue with the electrical checks below.
On this Whirlpool control family, the service tests typically include:
These tests are documented in Whirlpool’s service information, although the exact keypad sequence should be confirmed against the tech sheet for your model.
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With the evaporator cold enough for the thermostat to be closed, run the defrost heater test.
If the heater activates and begins melting frost, that confirms the heater circuit can operate. If it doesn’t, the next step is a voltage test.
Live Power Warning: This test involves approximately 120 VAC. Only perform it if you’re comfortable measuring live voltage.
With the heater connected and the defrost test active, measure AC voltage across the heater’s two supply connections.
Reading
What it tells us
Approximately 120 VAC and heater warms
Defrost heater circuit is operating
Approximately 120 VAC but no heat
Recheck heater connections and element
0 VAC
Check thermostat, wiring, and control output
Your 40-ohm heater reading suggests the element is good, but we still need to confirm it’s receiving power.
Also, make sure the thermostat was tested while it was cold. A defrost thermostat can test open at room temperature and still be functioning correctly.
If the ice is mainly at the bottom of the freezer, check the drain opening beneath the evaporator.
Make sure it isn’t plugged with ice or debris. Flush it with warm water until water flows freely into the drain pan underneath the refrigerator.
Since the control board has already been replaced and the heater measures 40 ohms, I’d focus on the defrost thermostat under operating conditions, the wiring connections, and whether the heater actually operates during a forced defrost.
One question that will help narrow this down:
When you say the coils frost over after two weeks, is the entire evaporator covered in thick white frost, or is there mainly a large buildup of ice along the bottom of the freezer?
That distinction will help determine whether we’re chasing a defrost failure or a drain problem.