Arkansas HVACR NewsMagazine January 2026

HVACR NewsMagazine January 2026

Tech News

Other Advantages of Demand Defrost Apart from the energy savings associated with fewer defrost cycles than a timed system (up to $400 a year), demand defrost could also lead to improved compressor longevity and reliability in the long run. We've talked a lot about the dangers of short cycling. Apart from the comfort issues associated with short cycles in humid climates, more frequent startups will strain the compressor motor. Defrost cycles are no different; the compressor runs during defrost to pump the hot discharge gas through the coils. Anytime we run a defrost cycle unnecessarily, the compressor has to start up again, which is hard on the motor and energy intensive. The White-Rodgers Universal Defrost Control does, however, force a defrost cycle after six hours to ensure adequate oil return. Oil return is crucial because the oil lubricates the bearings and keeps the compressor parts from wearing out, which also leads to premature failure. Sensor Location Accuracy is the key for defrost cycles, so we want to put the coil and outdoor air temperature sensors in specific areas. The coil temperature sensor comes with a clip and will typically be mounted to the lowest possible row of the condenser coil (not the liquid line). The goal is to make sure the sensor makes sufficient contact with the tubing so that it can pick up the coil temperature accurately. If you are replacing an OEM defrost board with a universal one, use the same spot as the previous coil sensor (unless there was something glaringly wrong with the original placement).

The placement of the outdoor air temperature is a little less straightforward. We don't want it to be in direct sunlight, so we need to mount it to a place where solar radiation won't skew the reading. It's usually fine enough to route the sensor through the grommets of the condenser side panel and fasten it to the thermostat cable and/or electrical whip.

Programming the Defrost Control for Demand Defrost If you install the White-Rodgers Universal Defrost Control, you could simply use its factory default settings, which are configured for demand defrost. With the control wired up properly and receiving power, press the "Option" until the display shows OE, and then press "Select." From there, you can cycle