Brand: KitchenAid
Model Number: KTRP19KRWH00
Main Symptom: Defrost heater short cycling
What happens & when:I have a 2005 KitchenAid KTRP19KRWH00 with an Invensys ADC2000. The refrigerator cools normally, but the defrost heater is being energized in repeated 20–30 second pulses with frequent relay clicking. Have you ever encountered that behavior on an ADC2000?
Error Code (if any):
Parts or tests already tried:
Photos / video link:
Yes—I have seen behavior that is very similar, and it is not normal operation for an Invensys ADC2000.
On an ADC2000, once a defrost cycle is initiated, the relay should energize the heater continuously until one of two things happens:
Repeated 20–30 second heater pulses with relay clicking are not part of the normal defrost algorithm.
1. Failing ADC2000 relay or board (most likely)
2. Intermittent feedback from the heater monitor circuit
The ADC2000 actually monitors heater operation through one of its inputs to determine how long the heater has been energized.
If that feedback becomes erratic because of:
the control can repeatedly drop out and retry.
3. Intermittent defrost thermostat
A weak bimetal usually causes one clean shutoff when it opens—not repeated 20-second cycling.
Only if the thermostat is right at its opening temperature and rapidly cooling/reheating would you expect repeated cycling, and even then it generally occurs near the end of defrost rather than throughout the cycle.
Clamp an ammeter around one heater lead and monitor:
while the evaporator is still well below freezing and the bimetal is known closed, I’d strongly suspect the ADC2000 itself.
Whirlpool issued a service pointer for certain refrigerators using the ADC2000 because of adaptive defrost behavior that could result in incomplete defrosts under some conditions. However, that issue involved the board’s defrost scheduling algorithm—not rapid relay pulsing during an active defrost.
If you can tell me:
I can probably narrow it down to either a board failure or an external component with fairly high confidence.
Yes compressor is off while these short pulses occur. No ice buildup. This is the text I sent to a few technicians. I got one response, stating it was out of his league. "I have a 2005 KitchenAid KTRP19KRWH00 refrigerator equipped with an Invensys ADC2000 Adaptive Defrost Controller.
Over the past few months I’ve noticed frequent relay clicking. Using a Home Assistant power monitor (Ikea Grillplats plug power into which the fridge is connected), I’ve observed that instead of a single normal defrost cycle, the ADC often energizes the defrost heater for two short 20–30 second pulses separated by a brief pause before returning to cooling. I’m wondering whether this behaviour could indicate a failing ADC2000 board, a problem with its adaptive control logic or stored parameters, or some other known issue with these controllers.
The refrigerator otherwise cools normally, and examining the evaporator coil shows a uniform ‘normal’ frost pattern, with no ice buildup.
I have also cleaned the condenser coils (it was very dusty); so everything is clean, but this odd behaviour remains."
This feels more like the controller making bad decision than a relay struggling to stay closed.
I’m tempted to disconnect R10 as the next step, to disable the adaptive behaviour.
Forced defrost seems to work fine. I’m confident that the power goes into the heater, based on the thermal lag/temperature monitor I have in the freezer compartment.
Almost definitely a board/relay issue
Could it be the low voltage rail to the micro sagging upon relay activation, as a result of degraded bulk capacitor on the ADC?
So I have two options so far: 1) pull R10 to see if that helps; I believe the defrost should then occur after 10 hours of compressor run time, or 2) replace the ADC2000, about $300CAD with tax. Fridge currently burns about 2kWh/day, about 30% higher than the advertised power consumption.
Yeah I’d start with pulling that r10 and see if it makes a difference
Also, have you actually seen repeated 20–30 second heater pulses disappear after lifting R10, or is this more of a diagnostic step to determine whether the adaptive algorithm is involved?
There were 105 short defrost events yesterday; this can’t be good the for the relay. I lifted one side of R10, and got two more short pulses since, so this suggests that nothing has changed and that these pulses are not caused by the adaptive algorithm.
The controller was observed to be a Microchip Tech P/N PIC16C54C.
I really suspect the relay/control board
So am I right in thinking that these short defrost pulses are not normal under any circumstances?
Exactly they are very indicative of something electronically wrong somewhere in the control sytem
Information that I have on my computer of using a regular timer or this one.I have not done this myself.I just save it if I ran into that expensive board.
WP2304099 SUPCO EDT11.pdf (106.0 KB)
KitchenAid KTRP19KRWH00 Refrigerator Service and Wiring Sheet - W10142143 - Rev A.pdf (529.5 KB)
Job Aid - 8178726 (R-107).pdf (165.6 KB)
Thank you. I saved those
Same thing, thanks for that, was looking for this too.
I’m still getting short defrost pulses with R10 pulled from my ADC2000 controller, leading me to look at the ETD11 as a possible way forward.
The SUPCO EDT11 only has four terminals (no neutral connection), so I’m assuming it uses the same principle as a conventional mechanical defrost timer. In other words, during cooling its internal timing circuit (equivalent to the timer motor in a mechanical timer) returns through the defrost heater and closed bi-metal thermostat, while during defrost it returns through the compressor run winding. See attached schematic.
If that’s correct, the EDT11’s schedule is effectively based on compressor run time, not simply elapsed clock time.
I was a bit confused by one YouTube installation where the installer connected terminal 3 directly to neutral. That would appear to power the timer continuously, making the defrost schedule based on elapsed time rather than compressor run time.
Am I understanding the EDT11 correctly? Is the intended installation to operate on compressor run time, with the neutral connection only being appropriate for special applications?
I did not realize there was a second relay in the “start device/overload assembly” barnacled to the compressor. That’s the relay that was clicking, not the one on the ADC2000. Either the start device has aged or the compressor is truly overheating. As the compressor seems to run fine and not consume more power than it should (I think), I’m hoping it’s just the start device. I ordered a new Start Device Kit - WP2225929.
Blowing some air on the start device/overload assembly (and the compressor) with a muffin fan eliminated the symptoms (compressor dropping out, evaporator fan/condenser fans still running) so I can live in hope that the compressor is still good on this 20 year-old fridge.
Below is the fridge power consumption, showing compressor cycling (normally I assume), drawing about 100W. Ambient temperature is 24°C.
