Carrier 50JS - Manual (Page 25)

Cooling and Heating Troubleshooting Chart (cont’d)
SYMPTOM CAUSE REMEDY
Suction pressure too low (Cool) Dirty air filter Replace filter
(Heat) Outdoor coil frosted
Move timer on control board to 30 min. between
defrost cycles
Low refrigerant charge Check for leaks, repair and recharge
Metering device or low side restricted Remove source of restriction
(Cool) Insufficient coil airflow
Increase air quantity
Check filter—replace if necessary
(Cool) Temperature too low in conditioned area Reset thermostat
(Cool) Outdoor ambient below 40°F Install low-ambient kit
Field-installed filter-drier restricted Replace
Compressor runs but outdoor fan does not
NC (normally closed) contacts on defrost board
open Check condition of relay on board
Replace if necessary
IFM does not run Blower wheel not secured to shaft Properly tighten blower wheel to shaft
Insufficient voltage at motor Determine cause and correct
Power connectors not properly sealed Connectors should snap easily; do not force
IFM runs when it should be off
Motor programmed with a delay profile Allow a few min. for motor to shut off
With thermostat in off state, the voltage on G,
Y1,Y, Y2, W with respect to common, should be
1/2 of actual low voltage supply If measured voltage is more than 1/2, the ther-
mostat is incompatible with motor
If voltage is less than 1/2, the motor has failed
IFM operation is intermittent
Water dripping into motor Verify proper drip loops in connector wires
Connectors not firmly sealed
Gently pull wires individually to be sure they are
crimped into the housing
IFM—Indoor Fan Motor
START-UP CHECKLIST
(REMOVE AND STORE IN JOB FILE)
I. PRELIMINARY INFORMATION
Model No...............................................................................................................................................................................................................
Serial No. ...............................................................................................................................................................................................................
Date ........................................................................................................................................................................................................................
Technician..............................................................................................................................................................................................................
II. PRE-START-UP
___ Verify that all packing materials have been removed from unit
___ Remove all shipping holddown bolts and brackets per installation instructions
___ Verify that condensate connection is installed per installation instructions
___ Check all electrical connections and terminals for tightness
___ Check that indoor (evaporator) air filter is clean and in place
___ Verify that unit installation is level
___ Check fan wheel and propeller for location in housing and setscrew tightness
III. START-UP
Supply Voltage: L1-L2 __________ L2-L3 _________ L3-L1 __________
Compressor Amps: L1 __________ L2 _________ L3 __________
Indoor Fan Amps: __________
TEMPERATURE
Outdoor-Air Temperature: __________ DB
Return-Air Temperature: __________ DB __________ WB
Heat Pump Supply Air: __________
Electric Heater Supply Air: __________
PRESSURES
Refrigerant Suction __________ psig
Refrigerant Discharge __________ psig
___ Verify refrigerant charge using charging tables
___ Verify 3-phase scroll compressor is rotating in correct direction
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