Set defrost timer on Paragon Electric Defrost-O-Matic

the problem is not necessarily with the timer. it seems you have more than ample time and time allocations to perform a complete defrost. most walk ins should have roughly 25-40 minutes of defrost every 4 to 8 hours. if you defrost with a heating element, you may have a problem with the strength of the element,or the element may be pulled away from the coil. you could also have a problem with the defrost thermostat(allowing the defrost to terminate prematurely)

If the air flow and temperature are not being compromised leave it alone. If there is a gradual build up of ice on the evaporator you may have a defrost element or defrost limit switch problem. Set the defrost duration duration to 45 minutes and see if that solves the icing problem. 4 defrost cycles a day should be enough to keep the icing problem at bay. 3 defrost cycles at night about 1 hour apart may also remedy the problem. Experiment until you find the right combination of defrost cycles for your freezer. Watch for any thawing of the product in the freezer and adjust accordingly.
Bills Refrigeration/Montana.