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Troubleshooting
Troubleshooting steps are listed in the following table.
Turn off all power to the unit before conducting any
troubleshooting procedures unless the procedure
Table 10. Troubleshooting methods
Symptom
Suction Pressure Too Low
Chilled Water Valve Fails to Open or Close
Evaporator Coil Ices
Blower Fails to Start
Control is Erratic
Condenser Pressure Too High
Condenser Pressure Too Low
AH-SVX008C-EN
specifically requires the system to operate. Keep hands,
clothing and tools clear of the electrical terminals and
rotating components. Equipment located in the ceiling can
pose unusual difficulties. Ensure that your footing is stable
at all times.
Probable Cause
a. Loss of refrigerant (excessive bubbles in
sight glass).
b. Expansion valve stuck or obstructed (short
cycle or continuous running).
c. Clogged drier/strainer (feels cold).
d. Dirty air filters.
a. Temperature setpoint too high/low.
b. No control power to the chilled water valve
c. Actuator failed.
Low airflow.
b.Temperature setting too low.
c.Discharge air short cycling back to return.
d.Low refrigerant charge.
a. Power failure.
b. Control transformer circuit breaker tripped.
c. Defective contactor. Repair or replace.
d.Thermal overload tripped.
Wiring improperly connected or broken.
a. Non-condensable gas or air in system.
b. Condenser air intake is blocked
c. Overcharge of refrigerant
d. Low water flow to water-cooled condenser
e. Condenser fan not operating
f. Water/glycol temperature too high.
g. Condenser pressure regulating valve setting
too high
h. Flow of water/glycol too low
i. Water/glycol solution not mixed prior to
adding to syste
a. Loss of refrigerant (indicated bubbles in sight
glass).
b. Condenser fan controls not set.
c.Water regulating valve adjusted too low.
Recommendation
Locate and repair leak. Remove and clean or
replace valve.
Replace with new drier/strainer.
Clean/replace filters.
Adjust to correct temperature setting
Thermostat wired incorrectly. Check wiring
diagram and rewire if required.
Replace actuator.
1.Check filters. Replace as needed.
2.Check for and clear any obstructions across or
in the (supply) discharge air- stream.
3.Check correct rotation of evaporator blower
Increase temperature setpoint (68°F
minimum.).
Check discharge grille orientation
Find leak, repair and recharge system
Check main voltage power source input cable.
Check for short circuit or ground fault; if none,
reset circuit breaker.
Repair or replace.
Reset overload and check amperage of motor.
Compare to setting on overload and adjust to
FLA. All direct-drive motors are internally
protected and do not require overload reset.
Check wiring against electrical drawing.
Recover system and recharge. Replace
drier/strainer. Evacuate to 50 microns and
recharge.
Remove debris and clean condenser.
Reclaim excess refrigerant from system.
Reset-determine cause and fix.
Check pressure/temperature operating
switches and motor. Replace as needed.
Check flow and operation of drycooler.
Adjust to obtain correct pressure.
1.Check glycol solution level and concentration.
2.Valves not open or partially open. Repair/
replace as needed.
3.Air in system - bleed system.
4.Check all strainers and clean if needed.
Remove solution and premix. Refill system.
Locate and repair leak. Recharge
Adjust or repair controls
R407C - Readjust to 320 psig.
Maintenance
41
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