SERVICING
21
S-2 CHECKING WIRING
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure 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
THERMOSTAT WIRE SIZING CHART
LENGTH OF RUN
MIN. COPPER WIRE
GAUGE (AWG)
25 feet 18
50 feet 16
75 feet 14
100 feet 14
125 feet 12
150 feet 12
S-3A THERMOSTAT AND WIRING
WARNING
Line Voltage now present.
With power ON, thermostat calling for cooling
1. Use a voltmeter to check for 24 volts at thermostat wires
C and Y in the unit control panel.
2. No voltage indicates trouble in the thermostat or wiring.
3. Check the continuity of the thermostat and wiring. Repair
or replace as necessary.
Indoor Blower Motor
With power ON:
WARNING
Line 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. Repair
or replace as necessary.
S-3B COOLING ANTICIPATOR
The cooling anticipator is a small heater (resistor) in the
thermostat. 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 changed.
S-4 CHECKING TRANSFORMER
AND CONTROL CIRCUIT
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do so
may cause property damage, personal injury
or death.
A step-down transformer (either 208-240, 460 or 575 volt pri-
mary to 24 volt secondary) is provided with each unit. This
allows ample capacity for use with resistance heaters.
WARNING
Disconnect ALL power before servicing.
1. Remove control panel cover to gain access to trans-
former.
With power ON:
WARNING
Line 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.
5 If line voltage available at primary voltage side of trans-
former and wiring and splices good, transformer is inop-
erative. Replace.
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