Carrier 50HQ - Manual (Page 14)

TROUBLESHOOTING CHART (cont)
PROBLEM
INSUFFICIENT
COOLING OR
HEATING
NOISY OPERATION
CAUSE
Unit undersized
Loss of conditioned air by
leaks
Thermostat
Airflow
Refrigerant charge
Compressor
Reversing valve
Operating pressure
Refrigerant system
Compressor
Contactors
Rattles and vibrations
Airborne noises and
other sounds
Blower and blower motor
CORRECTION
Recalculate heat gains or losses for space to be conditioned. If
excessive, rectify by adding insulation, shading, etc.
Check for leaks in ductwork or introduction of ambient air thru
doors and windows
Improperly located thermostat (e g near kitchen sensing in­
accurately the comfort level in living areas).
Lack of adequate airflow or improper distribution of air. _ _
Low on refrigerant charge causing inefficient operation.
Check for defective compressor. If discharge pressure is too low
and suction pressure is too high, compressor is not pumping
properly. Replace compressor.
Defective reversing valve creating bypass of refrigerant from dis­
charge to suction side of compressor
Incorrect operating pressure (See chart.) ________ _
Check strainer and capillary tubes for possible restrictions to flow
of refrigerant
__ _ _ _ _ __
The refrigerant system may be contaminated with moisture, non-
condensables, and particles _ ^ ____ _ _
Dehydrate, evacuate and recharge the system.
Make sure the compressor is not in direct contact with the base or
sides of the cabinet The holddown bolts used for shipping should
be loosened so that the compressor is floating free on its isolator
mounts. Excessive noise will occur if the compressor has a broken
valve or loose discharge tube. Replace the compressor______________ _
Blower wheel hitting the casing Adjust for clearance and align­
ment Bent blower, check and replace if damaged Loose blower
wheel on shaft Check and tighten Defective bearings, check and
replace
A clattering or humming noise in the contactor could be due to
control voltage less than 18 volts. Check for low supply voltage, low
transformer output or extra long runs of thermostat wires If the
contactor contacts or coil is defective, repair or replace
Check for loose screws, panels or internal components Tighten
and secure. Copper piping could be hitting the metal surfaces
Carefully readjust by bending slightly
Undersized ductwork will cause high airflow velocities and noisy
operation._____ _______ __ _____________ _ _____________ _____ ________
Excessive water thru the water-cooled heat exchanger will cause a
rattling sound
Throttle back on the water flow ensuring adequate flow for good
operation but eliminating the noise
For replacement items use Carrier Specified Parts.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
Tab 5a 5a
Form 50HQ,VQ-2SI Supersedes 50HQ,VQ-1 SI PrintedinUSA 9-81 PC 111 Catalog No 535-029