3
TROUBLESHOOTING GUIDE – REMOTE THERMOSTAT UNITS*
SYMPTOM
CAUSE
CHECK / CORRECTION
Unwanted source of heating or cooling is
near the wall thermostat causing the
thermostat to sense a temperature other
than room temperature.
Eliminate the unwanted heating or cooling source or move the
wall thermostat. See if thermostat is too close to a supply air
register. Seal the hole in the wall where the thermostat cable
passes into the thermostat.
Wall thermostat body may be heating up
due to impingement of direct sunlight, at a
certain time of day.
Relocate thermostat, provide shade for the thermostat, or just
live with the problem if it occurs for only a short time during
the day.
Thermostat does not
Properly Control Room
Temperature, Causes Unit
to Run Continuously, or
Causes Abnormal Cycle
Times in Heating or
Cooling Mode
Defective thermostat.
Test and replace if necessary.
Low voltage.
Check voltage with unit running and ensure it is within
nameplate limits.
Restricted condenser air.
Check for dirt or other condenser coil restriction. Clean as
necessary.
Recycling of condenser air.
Check for inadequate discharge air installation clearances.
Coil not sealed against grille. Unit may not be completely
pushed into sleeve
Condenser fan motor operating
intermittently, rotating slowly, or not at all.
Check to see if fan or shaft is rubbing or experiencing external
friction. Check free rotation of the motor shaft. Check voltage
to the motor. Check motor capacitor. Check for miswiring.
Motor may be seized internally. Motor may have open
windings, or defective internal overload – if so, replace motor.
Defective thermostat.
Test and replace if necessary.
Faulty or incorrect compressor overload.
Check for correct overload model number and replace if
incorrect. Otherwise, if running amps seem normal, replace
overload.
Indoor coil freezing.
See “Indoor Coil Frosts”
Compressor running too slow and drawing
high amps.
Compressor may be miswired. Check capacitor. Compressor
may be seizing – if so, replace compressor.
Indoor room temperature too cold.
Compressor will cycle on and off by command of the indoor
coil freeze protection device.
Compressor Short Cycles
Outdoor temperature too cold.
Compressor is not intended to operate at cold outdoor
temperatures. Compressor will cycle on and off by command
of the indoor coil freeze protection device.
System switch set OFF on wall thermostat
Switch to COOLING
Fuse or circuit breaker tripped.
Replace or reset as necessary.
Defective cooling relay.
Test and replace if necessary.
Defective switch.
Test and replace if necessary.
Defective thermostat.
Test and replace if necessary.
Indoor room temperature below thermostat
set point.
Lower thermostat setting if comfort not yet achieved.
Indoor room temperature too cold.
Compressor will cycle on and off by command of the indoor
coil freeze protection device.
Outdoor temperature too cold.
Compressor is not intended to operate at cold outdoor
temperatures. Compressor will cycle and then lock out by
command of the indoor coil freeze protection device, until the
outdoor temperature warms up.
Broken, shorted, loose, or miswired wiring.
Inspect and correct.
Defective compressor capacitor.
Test and replace if necessary.
Defective compressor overload.
Test and replace if necessary.
Low voltage or no voltage to compressor.
Check voltage and ensure it is within nameplate limits.
Compressor windings open.
Disconnect overload from compressor terminals. Check for
winding resistance across all winding pairs C-S, C-R, S-R and
check each terminal to the compressor shell for ground faults.
Replace compressor if any windings are open-circuited or
short circuited to the shell.
Compressor Will Not Run
Seized compressor.
If all of the above check out OK and if pressures are
equalized, and compressor draws high amps and will not
start, compressor is seized and needs to be replaced.
*This troubleshooting guide is intended for use by qualified service personnel.
Continued
