21
TROUBLESHOOTING GUIDE (MODELS 200-750)
SYMPTOM
POSSIBLE CAUSE(S)
CORRECTIVE ACTION
A) Water downstream of dryer
1. Residual free moisture remaining in
downstream pipelines
2. Air bypass system is open
3. Inlet and Outlet connections are reversed
4. Air lines downstream of dryer are exposed
to temperatures below the dew point.
5. Excessive free moisture (bulk liquid) at
dryer inlet.
6. Condensate not being drained
7. Dryer overloaded resulting in elevated
dew point.
8. Refrigeration system not functioning
1. Blow out system with dry air
2. Check valve positions
3. Check for correct connection
4. Insulate or heat trace air lines exposed to
low ambients or dry air to lower dew point
5. Install separator ahead of dryer
6. See C below
7. See C below
8. See C below
B) High pressure drop across dryer
1. Excessive air flow
2. Freezing of moisture in evaporator
because of refrigeration system fault
3. Filter loaded with solid particulates
1. Check flow rate
2. See C below
3. Replace filter element
C) Checkpoint faults
1. Power on light off
2. Compressor on light off
3. Alarm/Service alert light on
-check Display for active
conditions
SERVICE DRYER
LOW PRESSURE
HIGH PRESSURE
NOTE: If high refrigerant pressure
occurs, switch must be manually
reset
HIGH TEMPERATURE
(also observed as high reading on
temperature indicator)
DRAIN
COMPRESSOR
HEATER
TEMP SENSOR
a. Power failure; open circuit
a. Compressor commanded off by manual
switch or programmed schedule
b. Open circuit
c. Control circuit open on high or low
pressure cutout
a. Service interval specified has elapsed
a. Hot gas bypass valve requires adjustment
b. Low on refrigerant
a. Lack of condenser cooling
Air-cooled - Ambient temperature too
high, clogged condenser fins, obstructed
flow across condenser, faulty fan motor or
fan control switch.
Water-cooled - Cooling temperature too
high, flow too low, clogged strainer, faulty
water regulating valve
a. Dryer overloaded
b. Refrigeration system off or not cooling
sufficiently
a. Drain line restricted or frozen
b. Drain mechanism faulty
a. Faulty compressor contactor.
b. Faulty N.O. auxiliary contact on
compressor contactor.
a. Faulty compressor contactor.
b. Faulty N.C. auxiliary contact on
compressor contactor.
a. Temperature sensor or wiring to sensor
is open (only the left-most LED in the
temperature display will be illuminated).
b. Temperature sensor or wiring to sensor is
shorted (all of the LEDs in the temperature
display will be illuminated).
a. Check for power to dryer
a. Check current command status
b. Check power to compressor
c. Check display for fault
a. Perform scheduled service
a. Contact qualified technician or
manufacturer’s service department
Check air temperature 6” in front of
condenser; Clean condenser and check
for free air flow; Check fan and switch
operation
Check cooling medium temperature and
flow, clean strainer, check valve operation
a. Check compressed air flow, temperature,
and pressure
b. Check power to unit, power to
compressor, Low or High pressure faults
Have qualified technician evaluate system
a. Open drain line
b. Turn 3-way valve to horizontal position
and open petcock for manual draining.
Rebuild drain mechanism.
a. Check wiring and operation of contactor.
b. Check wiring and operation of auxiliary
contact.
a. Check wiring and operation of contactor.
b. Check wiring and operation of auxiliary
contact.
a. Replace sensor or repair wiring.
b. Replace sensor or repair wiring.
NOTE: After fault correction, press reset button to clear display
