Transducer Troubleshooting - Carrier WEATHERMASTER 48/50Z030-105 Operation And Service Manual

determining the resistance with unit shut down and thermistor
disconnected from J8. Compare the values determined with the
value read by the control in the Temperatures mode using the
scrolling marquee display.
Transducer Troubleshooting —
trol uses 2 suction pressure transducers to measure the suction
PROBLEM
Compressor and Fan Will Not
Start.
Compressor Cycles (Other Than
Normally Satisfying Thermostat).
Compressors Operates
Continuously.
Excessive Head Pressures.
Condenser Fans Not Operating.
Excessive Suction Pressure.
Suction Pressure Too Low.
LEGEND
CB — Circuit Breaker
TXV — Thermostatic Expansion Valve
The electronic con-
Table 71 — 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 call-
ing 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. Reset thermostat or schedule set point.
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.
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).
pressure of circuits A and B. The pressure/voltage characteris-
tics of these transducers are in shown in Tables 76 and 77. The
accuracy of these transducers can be verified by connecting an
accurate pressure gage to the second refrigerant port in the
suction line.
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.
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.
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.
86
REMEDY