Specifications

26
Low Suction pressure
Normal: 60 – 75 PSIG
Head pressure too low
Keep head pressure above
200 PSI by adjusting head
pressure regulator
Return air % RH level too low
Check register locations for
short-cycling of air.
Check setpoints; unit should
not be operating.
Insufficient evaporator air flow
Evaluate system air flow
Check for dirty filters or
restricted ductwork
Assure coils are not blocked or
dirty.
Close bypass damper to force
additional air across the coil.
Blocked filter drier
Evaluate filter pressure drop
and replace if necessary
Expansion valve not feeding
properly
Evaluate expansion valve
setting and performance.
Replace if necessary.
Restriction in refrigeration
piping
Check piping for kinks
High Head pressure
Normal: 200- 280 PSIG
Compressor discharge service
valves closed or not fully open
Fully open service valves
Excessive refrigerant charge
Check receiver sight glasses –
level indicators. Is the top ball
floating? Re-evaluate system
charge
Non-condensables in system Evacuate or purge system
Solenoid valve not opening
Check all solenoid valves
operation
Restriction in refrigeration
piping
Check coil and tubing for kinks
Refrigeration system is
overloaded
Check operating conditions
against the unit design
conditions on the nameplate. It
may be undersized.
Too much airflow across
evaporator
Verify the bypass damper is
open.
Balance the system airflow as
directed in section 6.4
Outdoor Condenser and Dry
Cooler related High Head
Pressure
Air on condenser temperature
above design condition.
If this is a chronic situation a
larger condenser or dry cooler
may be required.
Excessive pressure drop in
line sets
Re-evaluate remote
condenser installation and line
sizing
Fan motor overload tripped.
Reduce fan speed and reset
overload
Contactor faulty Replace contactor
Outdoor condenser fan does
not run.
Control wiring missing from
dehumidifier
ORI valve setting too high
Adjust ORI in water heating
mode so unit delivers 10
degrees of water heating.