Operating instructions

20
XIX. TROUBLESHOOTING GUIDE FOR UNIT OPERATION
PROBLEM
POSSIBLE CAUSE
CHECKS AND CORRECTIONS
Entire unit
does not run.
Blown Fuse/Tripped Circuit
Breaker
Replace fuse or reset circuit breaker. (Check for correct size fuse or circuit breaker.)
Blown Fuse on Controller
Replace fuse on controller. (Check for correct size fuse.) Check for loose fuse clips.
Broken or Loose Wires
Replace or tighten the wires.
Voltage Supply Low
If voltage is below minimum voltage on data plate, contact local power company.
Low Voltage Circuit
Check 24-volt transformer for burnout, blown fuse or voltage less than 18 volts.
Remote Hydronic Control
or Room Thermostat
Set system to "Cool" and lowest temperature setting, unit should run. Set system to "Heat" and
highest temperature setting, unit should run. If unit does not run in either case, the hydronic
control (or room thermostat) could be faulty or incorrectly wired. To prove faulty or miswired,
disconnect thermostat wires at the unit and jumper between "R", "Y" and "G" terminals, and unit
should run. Only replace with correct replacement. A substitute may not work properly.
Interruptible Power
Check incoming supply voltage.
Water
Lack of sufficient pressure, flow, temperature and/or quantity of water.
Unit Undersized
Recalculate heat gains or losses for space to be conditioned. If excessive, rectify by adding
insulation, shading, etc.
Loss of Conditioned Air by
Leaks
Check for leaks in ductwork or introduction of ambient air through doors and windows.
Thermostat
Improperly located thermostat (e.g. near kitchen sensing inaccurately the comfort level in living
areas). If thermostat has an anticipator, it should be set at 1.0 or 1.2.
Insufficient
cooling or
heating
Airflow (Across fan coil)
Lack of adequate airflow or improper distribution of air. Check the motor speed and duct sizing.
Check the filter, it should be inspected every month and changed if dirty. Remove or add
resistance accordingly.
Refrigerant Charge
Low on refrigerant charge causing inefficient operation. Adjust only after checking CFM, GPM
and inlet/outlet temperatures.
Compressor
Check for defective compressor. If discharge pressure is too low and suction pressure too high,
compressor is not pumping properly. Replace compressor.
Reversing Valve
Defective reversing valve creating bypass of refrigerant from discharge to suction side of
compressor. When it is necessary to replace the reversing valve, wrap it with a wet cloth and
direct the heat away. Excessive heat can damage the valve.
Desuperheater
The desuperheater circuit (in-line fuse) should be disconnected during cold weather to allow full
heating load to house.
Hydronic
pump runs
but
compressor
does not, or
compressor
short cycles.
Remote Hydronic Control
or Room Thermostat
Check setting and wiring. If thermostat has an anticipator, set it at 1.0 or 1.2.
Wiring
Check for loose or broken wires at compressor, capacitor, or contactor.
Blown Fuse
Replace fuse or reset circuit breaker. (Check for correct size fuse or circuit breaker.)
High Pressure or Low
Pressure Switch or
Discharge Refrigerant
Temperature Switch
The unit could be off on high pressure, low-pressure or discharge refrigerant temperature cutout.
Check water GPM and temperatures, ambient temperature and loss of refrigerant. If unit still
fails to run, individually check for faulty switches or wiring. Replace if defective.
Defective Capacitor
Check capacitor, if defective remove, replace, and rewire correctly.
Voltage Supply Low
If voltage is below minimum voltage specified on the data plate, contact local power company.
Check voltage at compressor for possible open terminal.
Low Voltage Circuit
Check 24-volt transformer for burn out or voltage less that 18 volts. With a voltmeter, check
signal from thermostat at Y to X, M1 on controller to X, capacitor voltage drop. Replace
component that does not energize.
Compressor Overload Open
In all cases an "internal" compressor overload is used. If the compressor motor is too hot, the
overload will not reset until the compressor cools down. If the compressor is cool and the
overload does not reset, there may be a defective or open overload. Replace the compressor.
Compressor Motor Shorted
to Ground
Internal winding grounded to the compressor shell. Replace the compressor. If compressor
burnout replace the liquid line filter/drier.
Compressor Windings Open
Check continuity of the compressor windings with an ohmmeter. If the windings are open,
replace the compressor.
Seized Compressor
Try an auxiliary capacitor in parallel with the run capacitor momentarily. If the compressor still
does not start, replace it.