Table N1: VHC-36, -42 and -50 Troubleshooting
Problem
Cause
Solutions
Compressor runs but stops quickly.
Overload, fuse burnout.
Check if voltage is too low, wiring is incorrect, wire gauge
is sized correctly; replace blown fuse.
Low or high pressure switch activated.
See solution for high pressure switch open and low
pressure switch open.
Compressor makes an abnormal
sound.
Reverse scroll operation.
Reverse any two phases on the three-phase compressor.
Compressor quality issue.
Replace compressor.
Excessive compressor vibration.
Compressor screw is loose.
Tighten the screw.
Compressor is running but there is no
pressure buildup.
Scroll reverse operation.
Reverse any two phases on the three-phase compressor.
Compressor system is normal but
amps are too high.
Incorrect compressor voltage.
Replace with correct voltage compressor.
High pressure switch is open in
cooling operation.
Condenser fan failed (AC system).
Check if wiring is correct; replace any failed components.
Lack of water flow (WSHP).
Check if the motorized water valve is opening completely
and confirm loop water pumps are running.
Water flow rate is too small (WSHP).
Check if pump sized correctly. If water strainer is installed
in line, check if strainer is too dirty.
Condenser is too dirty (AC system).
Clean condenser coil.
Ambient temperature exceeds
application upper limit (AC system).
Consult factory for operation out of application range.
Water entering temperature exceeds
application upper limit (WSHP).
Consult factory for operation out of application range.
Refrigerant overcharge.
Charge correct amount of refrigerant.
Non-condensable air accumulates in
the coaxial coil.
Vacuum system, re-charge refrigerant.
Coaxial coil scaled.
Clean coaxial coil.
High pressure switch is open in
heating operation.
Supply fan failure.
Check if wiring is correct, replace any failed components.
Outside air damper not open.
Check outside air damper operation and replace actuator
if failed.
Dx coil is too dirty.
Clean Dx coil.
Supply airflow is too small.
Check if components (coil, wheel, filter) are too dirty, motor
is running at low speed or not and check if there is too
much pressure loss in supply duct.
Refrigerant overcharge.
Charge correct amount of refrigerant.
Low pressure switch is open in cooling
operation.
TXV failed in closed position.
Replace TXV.
Supply blower failure.
Replace TXV or filter drier.
Insufficient supply airflow.
Check if components (coil, wheel, filter) are too dirty, motor
is running at low speed or not and check if there is too
much pressure loss in supply duct.
Loss of refrigerant charge.
Check and repair any leaks in the piping and refill
refrigerant.
Low pressure switch is open in heating
operation.
TXV failed in closed position.
Replace TXV.
Blocked TXV or filter drier.
Replace TXV or filter drier.
Lack of water flow (WSHP).
Check if motorized water valve is opening completely and
confirm loop water pumps are running.
Insufficient water flow (WSHP).
Check if pump is sized correctly or if water strainer is
blocked.
Water entering temperature too low
(WSHP).
Consult factory for operation out of application range.
Loss of refrigerant charge.
Check and repair any leaks in the piping and refill
refrigerant.
VCES-VHC-IOM-1F – VHC-36, -42 & -50
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