Troubleshooting - Modine Manufacturing Varsity ZCV Series Installation And Service Manual

TROUBLESHOOTING

Table 16.1 - Troubleshooting - General
Trouble
A. Unit Not Operating -
Power On
B. Unit Operating -
No Mechanical
Heating / Cooling
C. No Indoor Fan
D. Hot Water / Chilled
Water Valve Not
Operational (Option)
E. DX Split Units Only:
Low Suction Pressure
(LP Switch Tripped)
16
Possible Cause
1. Unit mounted disconnect in the "OFF" position.
2. Unit mounted 3-speed selector switch in the
"0" position.
3. Unit switched OFF in the microprocessor.
4. Delay on start set incorrectly.
5. Unit not in occupied mode.
6. Fire/smoke alarm tripped.
7. Tripped circuit breakers.
8. Loose mains or control wiring.
9. Occupancy sensor malfunction.
10. Hot water freeze protection (optional) stat
tripped.
1. Heating/cooling not required.
2. No output from microprocessor.
3. DX Split Units Only: HP/LP pressure safety
switch(es) tripped (open).
4. DX Split Units Only: Internal overload switch
on compressor tripped (open).
5. Loose control wiring connections.
6. Tripped circuit breakers.
7. Low temperature unit lockout.
8. DX Split Units Only: Compressor faulty.
9. Condensate pan/pump float switch tripped.
1. Motor tripped on internal overload.
2. Fan not required
3. No power to the fan.
4. Current sensor fault.
1. Heating not required.
2. Loose wiring connections.
3. Faulty heating actuator.
4. Isolation valves are open.
5. Check for DC control signal.
1. Low refrigeration charge.
2. Clogged filter(s).
3. Clogged liquid line filter drier.
4. Improper expansion valve setting or valve
malfunctioning.
5. Low/restricted supply airflow.
1. Turn the disconnect switch to the "ON" position.
2. Turn the 3-speed selector switch to the "1, 2, or 3" position.
3. Consult microprocessor documentation.
4. Consult microprocessor documentation.
5. Consult microprocessor documentation, and consult
microprocessor occupied setpoints.
6. De-energize and re-energize unit.
7. Reset the tripped circuit breaker(s).
8. With power OFF from distribution panel inspect the field
wiring connections in the electrical panel.
9. Inspect connections beginning with sensor input from the
microprocessor.
10. Manually reset at stat.
1. Verify applicable set point with return air temperature.
2. Consult microprocessor documentation.
3. Inspect high and low system pressures and wiring.
Check for dirty filters in Heat Pump mode.
4. Wait for compressor motor windings to cool down
(This switch is automatic reset).
5. Inspect connections beginning with compressor output
from the microprocessor.
6. Reset the tripped circuit breaker(s).
7. Consult microprocessor setpoints.
8. Replace compressor.
9. Check condensate pan/pump and piping for blockage.
1. Let motor cool down and reset - possible bad motor or
blocked filter.
2. Consult microprocessor documentation, or set thermostat
to "ON". Check if unit is in unoccupied and standby mode.
3. Check to make sure plugs are locked in place and all pins
are secure. Check for 24V control signal.
4. Make sure sensor is functioning correctly.
1. Consult microprocessor documentation.
2. Inspect connections beginning with valve output from the
microprocessor. Check to ensure 24V supply power is
present at actuator.
3. Replace actuator if faulty.
4. Check for additional external isolation valves.
5. Check for 2-10vDC signal from microprocessor.
1. Measure unit operating pressures. Add charge and check
for leaks.
2. Replace filter(s) as necessary.
3. Replace drier with a direct replacement. Follow proper
procedure.
4. Check operation and superheat settings.
5. Check diffusers, filters and supply motor to ensure
appropriate airflow.
AIR14-501.2
Possible Remedy