Goodman released Service Bulletin SR-072, regarding a software change on AVZC18 and AVZC20 Inverter Heat Pump units:
This bulletin is to inform you of a software change made to the Inverter Heat Pump models listed above. For units with a serial number prefix of 1706 and later the factory default setting for the defrost interval has been changed from 30 minutes to 120 minutes.
The defrost time interval can still be field adjustable to 30, 60, 90 or 120 minutes between defrost cycles to suit weather conditions and unit performance. This setting can be adjusted in the Comfortnet User Menu of the CTK04AE thermostat by selecting “Inverter” – “Heat Set Up” – “Defrost Interval”. When in this Sub Menu select 30, 60, 90,120 minutes setting.
NOTE: Oil Return Mode: In order to properly return the oil to the compressor, compressor speed may periodically adjust to assist oil circulation. These Inverter units utilize an oil return mode to properly return oil to the compressor which functions similar to a defrost cycle and may create the appearance of the unit having unnecessary defrosts.
If you have questions about this bulletin, HVAC Distributors customers can reach out to our Technical Service department at 800.228.4822 x5.