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45
Cooling Troubleshooting
Use the Scrolling Marquee display or a CCN device to view the
cooling status display and the cooling diagnostic display (see
Appendix A) for information on the cooling operation. Check the
current alarms and alarm history for any cooling alarm codes and
correct any causes. (See Table 12.) Verify any unique control
configurations per installed site requirements or accessories.
If alarms conditions are corrected and cleared, operation of the
compressors and fans may be verified by using the Service Test
mode. (See Table 4.) See Table 14 for general cooling service
analysis.
Table 14 – Cooling Service Analysis
PROBLEM
CAUSE
REMEDY
Compressor and Fan Will Not
Start.
Power failure.
Call power company.
Fuse blown or circuit breaker tripped. Check CB1,
CB2, and CB3.
Replace fuse or reset circuit breaker.
Disconnect off.
Power disconnect.
Compressor time guard to prevent short cycling.
Check using
Comfort
Link
Scrolling Marquee.
Thermostat or occupancy schedule set point not
calling for Cooling.
Check using
Comfort
Link
Scrolling Marquee.
Outdoor temperature too low.
Check Compressor Lockout Temperature using
Comfort
Link
Scrolling Marquee.
Active alarm.
Check active alarms using
Comfort
Link
Scrolling
Marquee.
Compressor Cycles (other than
normally satisfying thermostat).
Insufficient line voltage.
Determine cause and correct.
Active alarm.
Check active alarms using
Comfort
Link
S
crolling
Marquee.
Compressor Operates
Continuously.
Unit undersized for load.
Decrease load or increase size of unit.
Thermostat or occupancy schedule set point too low.
Reset thermostat or schedule set point.
Dirty air filters.
Replace filters.
Low refrigerant charge.
Check pressure, locate leak, repair, evacuate, and
recharge.
Condenser coil dirty or restricted.
Clean coil or remove restriction.
Excessive Condenser Pressures.
Loose condenser thermistors.
Tighten thermistors.
Dirty condenser coil.
Clean coil.
Refrigerant overcharge.
Recover excess refrigerant.
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line and insulate.
2. Replace TXV (and filter drier) if stuck open or
closed.
Condenser air restricted or air short cycling.
Determine cause and correct.
Restriction in liquid tube.
Remove restriction.
Condenser Fans Not Operating.
No Power to contactors.
Fuse blown or plug at motor loose.
Excessive Suction Pressure.
High heat load.
Check for sources and eliminate
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line and insulate.
2. Replace TXV (and filter drier) if stuck open or
closed.
Refrigerant overcharged.
Recover excess refrigerant.
Suction Pressure Too Low.
Dirty air filters.
Replace air filters.
Low refrigerant charge.
Check pressure, locate leak, repair, evacuate, and
recharge.
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line and insulate.
2. Replace TXV (and filter drier) if stuck open or
closed.
Insufficient evaporator airflow.
Check belt tension. Check for other restrictions.
Temperature too low in conditioned area (low
return‐air temperature).
Reset thermostat or occupancy schedule.
LEGEND
CB
- Circuit Breaker
TXV
- Thermostatic Expansion Valve
48/50PG and PM
Summary of Contents for 48/50PG C03-14
Page 31: ...31 C07009 Fig 18 Air Baffle Dimensions 48 50PG03 16 48 50PG and PM...
Page 32: ...32 C08077 Fig 19 Air Baffle Dimensions 48 50PM16 28 48 50PG and PM...
Page 56: ...56 C08549 Fig 25 48PG03 16 Control Wiring Schematic 48 50PG and PM...
Page 57: ...57 C08550 Fig 26 50PG03 16 Control Wiring Schematic 48 50PG and PM...
Page 62: ...62 C08471 Fig 31 Typical 48PM16 28 Control Schematic 48 50PG and PM...
Page 63: ...63 C08062 Fig 32 Typical 48PM16 28 with Humidi MiZert System Control Schematic 48 50PG and PM...
Page 64: ...64 C101251 Fig 33 Typical 50PM16 28 Control Schematic 48 50PG and PM...
Page 65: ...65 C08064 Fig 34 Typical 50PM16 28 with Humidi MiZert Control Schematic 48 50PG and PM...
Page 66: ...66 C10902 Fig 35 Typical 48 50PM16 28 Power Schematic 48 50PG and PM...
Page 67: ...67 C09213 Fig 36 Typical 48 50PM16 28 with Humidi MiZert System Power Schematic 48 50PG and PM...
Page 69: ...69 C08067 Fig 38 48 50PM16 28 Component Arrangement 48 50PG and PM...
Page 70: ...70 C101252 Fig 39 48 50PM16 28 with Humidi MiZert Component Arrangement 48 50PG and PM...