Troubleshooting - Modine Manufacturing VFV Series Installation And Service Manual

TROUBLESHOOTING

Table 33.1 - 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)
Possible Cause
1. Unit mounted disconnect in the "OFF" position.
2. Unit mounted 3-speed selector switch in the "0"
position (if equipped with a 4-position switch).
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.
14-500.7
Possible Remedy
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.
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