25
M
INI
-S
PACE
EC I
NSTALLATION
, O
PERATION
AND
M
AINTENANCE
M
ANUAL
SYMPTOM
PROBABLE CAUSE
RECOMMENDATION
Suction Pressure Too Low
a. Loss of refrigerant (excessive bubbles in
sight glass).
Locate leak and repair. Recharge system.
b. Expansion valve stuck or obstructed
(short cycle or continuous running).
Remove and clean or replace valve.
c. Clogged drier/strainer (feels cold).
Replace with new drier/strainer.
d. Dirty air fi lters.
Clean/replace fi lters.
Water/Glycol Valve Fails to Open
or Close
a. Temperature set point too high.
Adjust to correct temperature setting.
b. No control power to the valve.
Thermostat wired incorrectly. Check wiring
diagram and rewire if required.
c. Actuator failed.
Replace actuator.
Evaporator Coil Ices
a. Low airfl ow.
1. Check fi lters. 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.
b. Temperature setting too low.
Increase temperature setpoint (68 °F min.).
c. Discharge air short cycling back to return.
Check discharge grille orientation.
d. Low refrigerant charge.
Find leak, repair and
recharge system.
Blower Fails to Start
a. Power failure.
Check main voltage power source input
cable.
b. Control transformer circuit breaker
tripped.
Check for short circuit or ground fault; if
none, reset circuit breaker.
c. Defective contactor.
Repair or replace.
d. Condensate Switch Open.
Insure unit is level.
Check that condensate pan is draining
properly. Clear obstructions.
e. Motor starter protector tripped
Reset motor starter protector and check
amperage of motor. Compare to setting of
motor protector and adjust FLA.
Control is Erratic
Wiring improperly connected or broken.
Check wiring against electrical drawing.
Table 8.
Troubleshooting Guide
