610.020-IOM (NOV 19)
Page 19
EVAPORATOR AND AIR COOLER
INSTALLATION - OPERATION - MAINTENANCE
Table 10: Air cooler troubleshooting guide
Symptoms Possible cause Corrective action
1. Fan motors not running Main switch open Close switch
Blown fuse or fuses Replace fuse or fuses
Check for short circuits or overload
conditions
Faulty motor or motors Replace motor or motors
Unit currently in defrost mode Wait for completion of defrost cycle
2. Elevated room temperature Incorrect thermostat setting (too high) Adjust thermostat setting
Low refrigerant charge Add refrigerant
Superheat setting too high Adjust thermal/electronic expansion valve
Evaporators are undersized for room / load If design load has increased, operating
conditions might require change. Alterna-
tively, add more evaporators to the space
Coil iced up Manually defrost coil and adjust defrost
settings
High inltration load Ensure all openings in space are properly
sealed
Low refrigerant ow into evaporator Check fans / motors for correct operation
(rotation)
Check and clean strainers
Adjust hand expansion valve setting
3. Ice accumulation on ceiling
around evaporator or around
fans, motors and fan nozzles
Defrost duration too long Adjust defrost settings
Too many defrosts Decrease defrost frequency
Defective defrost timer / thermostat /
defrost relief regulating valve
Repair or replace defective components
Fan delay not set correctly Adjust setting for fan delay duration
CLEANING
WARNING
All power must be disconnected and locked out before
any cleaning. The drain pan also serves as a cover for
hazardous moving parts. Operation of unit without drain
pan constitutes a hazard.
Keep coils clean to maintain optimum performance. During
periods of high cooling demand or when dirty conditions
prevail, clean the coil more regularly. Always remove large
debris from the coil and straighten ns before cleaning.
When using a high pressure washer to clean the coil, the
spray pressure must not exceed 1,100 psig (75 bar) and
the spray head must be at least 12 in. (300 mm) away from
the nned surface area. Ensure the spray angle is no wider
than 15° and that it is directed perpendicular to the coil
face area.
CAUTION
Do not use acidic chemical coil cleaners. Do not use
alkaline chemical coil cleaners that, after mixing,
have a ph value greater than 8.5 without also using
an aluminum corrosion inhibitor in the cleaning solu-
tion. Failure to follow these instructions could result in
severe corrosion to the nned surface area. Cleaning
and sanitizing solutions must be compatible with the
materials of construction of the unit.
WARNING
Some chemical coil–cleaning compounds are caustic
and toxic. Use these substances only in accordance with
the manufacturer’s instructions. Failure to do so could
result in serious injury, death or equipment damage.
Coil cleaning and sanitizing agents are available from the
following companies, dependent on materials of construc-
tion of the air unit: Zep Inc., DuChem, Nalco, and Hydro
Balance.
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