Frick AGHN - Page 20

610.020-IOM (NOV 19)
Page 20
EVAPORATOR AND AIR COOLER
INSTALLATION - OPERATION - MAINTENANCE
Table 10: Air cooler troubleshooting guide (continued)
4. Coil not clearing of frost during
defrost cycle
Insufcient defrost cycles in 24 hour period Increase defrost frequency
Defrost cycle too short Adjust defrost setting for increased dura-
tion
Hot gas volume insufcient Increase ow to evaporator
Hot gas temperature / pressure too low Increase hot gas temperature / pressure
Defective timer or relief regulating valve Replace timer or regulating valve
Fans continue to run when in defrost mode Adjust settings to prevent fans running
Excessive inltration load Ensure all openings in space are properly
sealed
5. Uneven coil frosting Defective heater element or elements Replace element or elements
Unit located too close to a door or opening Relocate evaporator
Refrigerant feed insufcient to properly
feed evaporator
Check and clean strainers
Adjust hand expansion valve setting
Adjust thermal expansion valve (TXV)
settings
Defrost duration too short Adjust defrost settings
TXV too small Replace with correct TXV
Fans not functioning correctly Check fans and motors for correct opera-
tion, and replace if defective
6. Ice accumulation in drain pan Defective heater element or elements Replace element or elements
Unit incorrectly pitched Check and adjust accordingly
Condensate drain line plugged Clean drain line
Defective drain line heater Replace heater
Insufcient hot gas ow to unit Increase hot gas ow to unit
Defective defrost timer / thermostat /
defrost relief regulating valve
Repair or replace defective components
7. Low airow Coil iced up See symptoms 3, 4, and 5 above
Unit mounted too close to a wall Reposition unit for unobstructed airow
VFD output too low Adjust VFD settings
Fans not functioning correctly Check fans and motors for correct opera-
tion, and replace if defective
8. Insufcient airthrow Air discharge area obstructed Remove / replace any items causing an
obstruction to the discharge air
Fit streamers on air unit
NOTICE
Ice has a much higher density than frost and requires more time to melt than the normal frost formation on a coil. Ice
can form from melted frost which is not drained from the unit during the defrost cycle. Over time this accumulation
can become signicant and can lead to other problems at the evaporator. It is essential that air coolers are regularly
inspected to ensure effective defrost performance. Manual ice removal may be required in some instances to remove
this ice accumulation.
Before any inspection involving frost or ice accumulation, the coil and all sheet metal components must be thoroughly
cleaned of all ice accumulation.