I used the following code to generate the defrost schedule for the air chiller object. For refrigerated warehouse a more frequent defrost schedule than typical may be required.

# Create #create a new defrost schedule defrost_schedule using ScheduleCompact
ScheduleRuleset
defrost_schedule = OpenStudio::Model::ScheduleCompact.new(model)
defrost_schedule.setName("RefrigeratedWarehouse.idf OpenStudio::Model::ScheduleRuleset.new(model)
defrost_schedule.setName("Frequent Defrost Schedule")

# Set schedule type limits
discrete_type_limits default_day = OpenStudio::Model::ScheduleTypeLimits.new(model)
discrete_type_limits.setName("ON/OFF")
discrete_type_limits.setLowerLimitValue(0)
discrete_type_limits.setUpperLimitValue(1)
discrete_type_limits.setNumericType("Discrete")
defrost_type_limits = discrete_type_limits
defrost_schedule.setScheduleTypeLimits(defrost_type_limits)

# Define the schedule values using Schedule:Compact format
# Defrost schedule matches AirChillerDefrostSched1 in RefrigeratedWarehouse.idf
defrost_schedule.addValue("Through: 12/31")
defrost_schedule.addValue("For: AllDays")
defrost_schedule.addValue("Until: 05:00", 0) 
defrost_schedule.addValue("Until: 05:20", 1)
defrost_schedule.addValue("Until: 22:00", 0)
defrost_schedule.addValue("Until: 22:40", 1)
defrost_schedule.addValue("Until: 24:00", 0)

# Create an air chiller using defrost_schedule above
air_chiller = OpenStudio::Model::RefrigerationAirChiller.new(model, defrost_schedule)
defrost_schedule.defaultDaySchedule
default_day.setName("Default Day Schedule")

I used the following code to generate the defrost schedule for the air chiller object. For refrigerated warehouse a more frequent defrost schedule than typical may be required.

note: generative A.I. was used to inform this code.

#create a defrost_schedule using ScheduleRuleset
defrost_schedule = OpenStudio::Model::ScheduleRuleset.new(model)
defrost_schedule.setName("Frequent Defrost Schedule")
default_day = defrost_schedule.defaultDaySchedule
default_day.setName("Default Day Schedule")

# Define hourly values for the default day with six defrost cycles per day # Each cycle lasts for 30 minutes and occurs every 4 hours default_day.addValue(OpenStudio::Time.new(0, 0, 0, 0), 0.0) # Start with no defrost default_day.addValue(OpenStudio::Time.new(0, 0, 30, 0), 1.0) # Defrost from 12:00 AM to 12:30 AM default_day.addValue(OpenStudio::Time.new(0, 4, 0, 0), 0.0) # No defrost from 12:30 AM to 4:00 AM default_day.addValue(OpenStudio::Time.new(0, 4, 30, 0), 1.0) # Defrost from 4:00 AM to 4:30 AM default_day.addValue(OpenStudio::Time.new(0, 8, 0, 0), 0.0) # No defrost from 4:30 AM to 8:00 AM default_day.addValue(OpenStudio::Time.new(0, 8, 30, 0), 1.0) # Defrost from 8:00 AM to 8:30 AM default_day.addValue(OpenStudio::Time.new(0, 12, 0, 0), 0.0) # No defrost from 8:30 AM to 12:00 PM default_day.addValue(OpenStudio::Time.new(0, 12, 30, 0), 1.0) # Defrost from 12:00 PM to 12:30 PM default_day.addValue(OpenStudio::Time.new(0, 16, 0, 0), 0.0) # No defrost from 12:30 PM to 4:00 PM default_day.addValue(OpenStudio::Time.new(0, 16, 30, 0), 1.0) # Defrost from 4:00 PM to 4:30 PM default_day.addValue(OpenStudio::Time.new(0, 20, 0, 0), 0.0) # No defrost from 4:30 PM to 8:00 PM default_day.addValue(OpenStudio::Time.new(0, 20, 30, 0), 1.0) # Defrost from 8:00 PM to 8:30 PM default_day.addValue(OpenStudio::Time.new(0, 24, 0, 0), 0.0) # No defrost from 8:30 PM to 12:00 AM

I used am currently trying to do the following code exact same thing, and am encountering the exact same issue. If you have any insight into this, happy to generate the defrost schedule for the air chiller object. For refrigerated warehouse a more frequent defrost schedule than typical may be required.discuss.

#create a defrost_schedule using ScheduleRuleset
defrost_schedule = OpenStudio::Model::ScheduleRuleset.new(model)
defrost_schedule.setName("Frequent Defrost Schedule")
default_day = defrost_schedule.defaultDaySchedule
default_day.setName("Default Day Schedule")