Trane CGA-SVX01A-EN Installation, Operation And Maintenance Manual page 30

K. Discharge Pressure Too Low
Probable Cause
(1) Shortage of refrigerant (i.e., low subcooling, high superheat,
bubbles in sight glass)
(2) Broken or leaky compressor discharge valves
(3) Defective low pressure switch
(4) Unit running below minimum operating ambient
L. Discharge Pressure Too High
Probable Cause
(1) Too little or too warm condenser air; airflow restricted
(2) Air or non-condensable gas in system (i.e., exceptionally hot
condenser)
(3) Refrigerant overcharge (i.e., high subcooling, low superheat,
high suction pressure)
(4) Excessive system load
(5) Defective condenser fan or fan pressure control (i.e., 1 fan off,
high condenser pressure)
M. System Cannot Heating Mode (CGAR Model Only)
Probable Cause
(1) Broken or improper control wiring
(2) Defective four-way valve
N. Suction Pressure Too Low - Heating Mode (CGAR Model Only)
Probable Cause
(1) Low refrigerant charge
(2) Too little or too cold evaporator air; airflow restricted
(3) Unit running below minimum operating ambient
(4) Expansion valve power assembly has lost charge
O. Discharge Pressure Too High - Heating Mode (CGAR Model Only)
Probable Cause
(1) Low water flow
(2) Defective heating thermostat switch
© American Standard Inc. 2001
Recommended Action
Find and repair leak; recharge system
Replace compressor
Replace defective control
Provide adequate head pressure controls, or an ambient lockout
switch
Recommended Action
Clean coil; Check fans and motors for proper function
Evacuate and recharge system
Recover excess refrigerant
Reduced load
Repair or replace switch
Recommended Action
Check control wiring
Replace four-way valve
Recommended Action
Add refrigerant
Clean coil; Check fans and motors for proper function
Provide an ambient lockout switch
Repair or replace expansion valve power head assembly
Recommended Action
Check for clogged strainers and incorrect balancing valve settings
a. Verify that sense bulb is properly inserted bulbwell of
heat-exchanger
b. Replace heating thermostat switch
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CGA-SVX01A-EN