SERVICING
36
If the imbalance had not changed then the problem would lie
within the equipment. Check for current leakage, shorted
motors, etc.
S-2 CHECKING WIRING
WARNING
HIGH
VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY
BE PRESENT.
F
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Check wiring visually for signs of overheating, damaged
insulation and loose connections.
2. Use an ohmmeter to check continuity of any suspected
open wires.
3. If any wires must be replaced, replace with comparable
gauge and insulation thickness.
S-3 CHECKING THERMOSTAT, WIRING, AND
ANTICIPATOR
S-3A Thermostat and Wiring
WARNING
L
INE VOLTAGE NOW PRESENT.
With power ON and thermostat calling for cooling.
1. Use a voltmeter to check for 24 volts at thermostat wires
C and Y in the control panel.
2. No voltage indicates trouble in the thermostat, wiring or
external transformer source.
3. Check the continuity of the thermostat and wiring. Re-
pair or replace as necessary.
Indoor Blower Motor
With power ON:
WARNING
L
INE VOLTAGE NOW PRESENT.
1. Set fan selector switch at thermostat to "ON" position.
2. With voltmeter, check for 24 volts at wires C and G.
3. No voltage, indicates the trouble is in the thermostat or
wiring.
4. Check the continuity of the thermostat and wiring. Re-
pair or replace as necessary.
Resistance Heaters
1. Set room thermostat to a higher setting than room temp
so both stages call for heat.
2. With voltmeter, check for 24 volts at each heater relay.
3. No voltage, indicates the trouble is in the thermostat or
wiring.
4. Check the continuity of the thermostat and wiring. Re-
pair or replace as necessary.
NOTE:
Consideration must be given as to how the heaters
are wired (O.D.T. and etc.). Also safety devices must be
checked for continuity.
S-3B Cooling Anticipator
The cooling anticipator is a small heater (resistor) in the ther-
mostat. During the "off" cycle it heats the bimetal element
helping the thermostat call for the next cooling cycle. This
prevents the room temperature from rising too high before the
system is restarted. A properly sized anticipator should
maintain room temperature within 1 1/2 to 2 degree range.
The anticipator is supplied in the thermostat and is not to be
replaced. If the anticipator should fail for any reason, the
thermostat must be replaced.
S-3C Heating Anticipator
The heating anticipator is a wire-wound adjustable heater,
which is energized during the "ON" cycle to help prevent over-
heating of the conditioned space.
The anticipator is a part of the thermostat and if it should fail
for any reason, the thermostat must be replaced. See the
following for recommended heater anticipator setting.
The first stage heat anticipator setting for heat pump models
is .40. The heat anticipator setting for the package gas mod-
els is .80.
S-4 CHECKING TRANSFORMER AND CON-
TROL CIRCUIT
A step-down transformer (208/240 volt primary to 24 volt sec-
ondary) is provided with each package unit. This allows ample
capacity for use with resistance heaters.
WARNING
D
ISCONNECT ELECTRICAL POWER SUPPLY.
1. Remove control panel cover or etc. to gain access to trans-
former.
With power ON:
WARNING
L
INE VOLTAGE NOW PRESENT.
2. Using a voltmeter, check voltage across secondary volt-
age side of transformer (R to C).
3. No voltage indicates faulty transformer, bad wiring, or bad
splices.
4. Check transformer primary voltage at incoming line volt-
age connections and/or splices.
