Carrier Weathermaster 48P030-100 Controls, Start-Up, Operation, Service, And Troubleshooting page 107

PROBLEM
Compressor and Fan Will Not Start
Compressor Cycles (Other Than
Normally Satisfying Thermostat)
Compressors Operate Continuously
Excessive Head Pressures
Condenser Fans Not Operating
Excessive Suction Pressure
Suction Pressure Too Low
LEGEND
CB — Circuit Breaker
TXV — Thermostatic Expansion Valve
Table 86 — Cooling Service Analysis
CAUSE
Power failure.
Fuse blown or circuit breaker tripped. Check CB1, CB2, and
CB3.
Disconnect off.
Compressor time guard to prevent short cycling.
Thermostat or occupancy schedule set point not calling for
Cooling.
Outdoor temperature too low.
Active alarm.
Insufficient line voltage.
Active alarm.
Unit undersized for load.
Thermostat or occupancy schedule set point too low.
Dirty air filters.
Low refrigerant charge.
Condenser coil dirty or restricted.
Loose condenser thermistors.
Dirty condenser coil.
Refrigerant overcharge.
Faulty TXV.
Condenser air restricted or air short cycling.
Restriction in liquid tube.
No Power to contactors.
Condenser Fan slips on shaft.
Motor overload open.
Motor burned out.
VFDs not functioning.
High heat load.
Faulty TXV.
Refrigerant overcharged.
Dirty air filters.
Low refrigerant charge.
Faulty TXV.
Insufficient evaporator airflow.
Temperature too low in conditioned area (low return-air
temperature).
Call power company.
Replace fuse or reset circuit breaker.
Power disconnect.
Check using ComfortLink scrolling marquee.
Check using ComfortLink scrolling marquee.
Check Compressor Lockout Temperature (MC.LO) using
ComfortLink scrolling marquee.
Check active alarms using ComfortLink scrolling 
marquee.
Determine cause and correct.
Check active alarms using ComfortLink scrolling 
marquee.
Decrease load or increase of size of unit.
Reset thermostat or schedule set point.
Replace filters.
Check pressure, locate leak, repair evacuate, and recharge.
Clean coil or remove restriction.
Tighten thermistors.
Clean coil.
Recover excess refrigerant.
1. Check TXV bulb mounting and secure tightly to suction
line and insulate.
2. Replace TXV (and filter drier) if stuck open or closed.
Determine cause and correct.
Remove restriction.
Fuse blown or plug at motor loose.
Tighten fan hub setscrews.
Check overload rating. Check for fan blade obstruction.
Replace motor.
Verify the VFDs; replace if needed.
Check for sources and eliminate
1. Check TXV bulb mounting and secure tightly to suction
line and insulate.
2. Replace TXV (and filter drier) if stuck open or closed.
Recover excess refrigerant.
Replace air filters.
Check for leaks, repair, and recharge.
1. Check TXV bulb mounting and secure tightly to suction
line and insulate.
2. Replace TXV (and filter drier) if stuck open or closed.
Check belt tension. Check for other restrictions.
Reset thermostat or occupancy schedule.
107
REMEDY