Carrier SUPRA 950Mt - Defrost Cycle Malfunction; Abnormal Pressure, Cooling

62-11863 6-4
6.3.5 Defrost Cycle Malfunction
Will not initiate defrost auto-
matically
Defrost thermostat (DTT) open or defective
Loose terminal connections
Check the selected Defrost Interval
Replace
Tighten
Check
Will not initiate defrost manual-
ly
Microprocessor or Cab Command defective
Loose terminal connections
Defrost thermostat (DTT) open or defective
Replace
Tighten
Replace
Initiates but does not defrost Hot gas valve malfunction
Defrost relay (DR) defective
Electric heater inoperative
6.3.11
Replace
Check
Frequent defrost Defrost timer to be adjusted 3.15.2
Does not terminate within 45
minute maximum allowable
time
Defrost thermostats (DTT) shorted closed
Wet load
Replace
Check
6.3.6 Abnormal Pressure, Cooling
High discharge pressure Condenser coil dirty or air flow restricted
Condenser fan defective
Loose or broken V-belt
Discharge check valve restricted
Non-condensibles or refrigerant overcharge
Hot gas valve (1HGV or 2HGV) malfunction
5.14.2
Check
5.3
Replace
Replace
6.3.11
Low discharge pressure Compressor valve(s) worn or broken
Low refrigerant charge
Hot gas valve (1HGV or 2HGV) malfunction
5.8
5.4.1
6.3.11
High suction pressure Compressor valve(s) worn or broken
Compressor Pressure Regulator (CPR) valve not adjusted
properly
Compressor gasket(s) defective
Hot gas valve (1HGV or 2HGV) malfunction
5.8
5.15
5.8
6.3.11
Low suction pressure Suction service valve partially closed
King valve partially closed
Compressor Pressure Regulator (CPR) valve not adjusted
properly
Filter-drier partially plugged
Low refrigerant charge
Expansion valve malfunction
No evaporator air flow or restricted air flow
Excessive frost on coil
Open
Open
5.15
5.11
5.7
6.3.10
6.3.9
Check
Suction and discharge pres-
sures tend to equalize when
unit is operating
Compressor valves defective
Hot gas valve (1HGV or 2HGV) malfunction
5.8
6.3.11