104
Table 72 —
Cooling Service Analysis
LEGEND
PROBLEM
CAUSE
REMEDY
Compressor and Fan Will Not Start
Power failure.
Check power source. Call power company.
Fuse blown or circuit breaker tripped. Check fuses and
circuit breakers in power and control panels.
Replace fuse or reset circuit breaker.
Disconnect off.
Power disconnect.
Compressor time guard to prevent short cycling.
Check using
Comfort
Link
Navigator display.
Thermostat or occupancy schedule set point not
calling for Cooling.
Check using
Comfort
Link
Navigator display.
Outdoor temperature too low.
Check Compressor Lockout Temperature (
MC.LO
)
using
Comfort
Link
Navigator display.
Active alarm.
Check active alarms using
Comfort
Link
Navigator
display.
Compressor Cycles (Other Than
Normally Satisfying Thermostat)
Insufficient line voltage.
Determine cause and correct.
Active alarm.
Check active alarms using
Comfort
Link
Navigator
display.
Compressor Operates
Continuously
Unit undersized for load.
Decrease load or increase of 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 Head Pressures
Loose condenser thermistors.
Tighten thermistors.
Dirty condenser coil.
Clean coil.
Refrigerant overcharge.
Recover excess refrigerant.
Faulty EXV.
1.
Check ST thermistor mounting and secure tightly
to suction line and insulate.
2.
Replace EXV (and filter drier) if stuck open or
closed.
3.
Run EXV auto-component test.
EXV board malfunction.
Check alarm history for A169 (expansion valve control
board comm. failure).
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 EXV.
1.
Check ST thermistor mounting and secure tightly
to suction line and insulate.
2.
Replace EXV (and filter drier) if stuck open or
closed.
3.
Run EXV auto-component test.
EXV board malfunction.
Check alarm history for A169 (expansion valve control
board comm. failure).
Refrigerant overcharged.
Recover excess refrigerant.
Suction Pressure Too Low
Dirty air filters.
Replace air filters.
Low refrigerant charge.
Check for leaks, repair, and recharge.
Faulty EXV.
1.
Check ST thermistor mounting and secure tightly
to suction line and insulate.
2.
Replace EXV (and filter drier) if stuck open or
closed.
3.
Run EXV auto-component test.
EXV board malfunction.
Check alarm history for A169 (expansion valve control
board comm. failure).
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.
EXV
—
Expansion Valve Control Board
ST
—
Suction Temperature
Содержание WeatherExpert 48N2
Страница 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Страница 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Страница 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Страница 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Страница 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Страница 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Страница 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Страница 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Страница 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Страница 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Страница 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Страница 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Страница 168: ...168 Fig 47 Sensor and Ignition Position Fig 48 Combustion Blower Details SENSOR DETAILS IGNITION DETAILS ...
Страница 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...