Install Instructions

56
IOM - HZH/HZV Series
Low Air Coil Temperature
Fault - (ClimaDry) Code 12
X
Reduced airflow in cooling, ClimaDry, or
constant fan
Check for dirty air filter and clean or replace
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
Air temperature out of range Too much cold vent air - bring entering air temp within design parameters
Bad thermistor Check temp and impedance correlation per chart
ESD - ERV Fault (DXM Only)
Green Status LED Code 3
X X ERV unit has fault (Rooftop units only) Troubleshoot ERV unit fault
No Fault Code Shown
X X
No compressor operation See ‘Only Fan Operates’
Compressor overload Check and replace if necessary
Control board Reset power and check operation
Unit Short Cycles
X X
Dirty air filter Check and clean air filter
Unit in ‘Test Mode’ Reset power or wait 20 minutes for auto exit
Unit selection Unit may be oversized for space - check sizing for actual load of space
Compressor overload Check and replace if necessary
Only Fan Runs
X X
Thermostat position Ensure thermostat set for heating or cooling operation
Unit locked out Check for lockout codes - reset power
Compressor overload Check compressor overload - replace if necessary
Thermostat wiring
Check thermostat wiring at DXM2 - put in Test Mode and jumper Y1 and R to
give call for compressor
Functional Troubleshooting (cont.)
Fault Htg Clg Possible Cause Solution