Outdoor Thermostat(S); Compressor Plug; Low-Voltage Terminals - Carrier R-22 Application Manual And Service Manual

If service alarm needs replacing, shut off all power to unit
before attempting removal. Electrical shock can cause per-
sonal injury or death.
Troubleshooting service-alarm device is easy. With thermostat
calling for heating or cooling and compressor running, indoor
thermostat light should be off. If on, check for wiring errors or
replace the service alarm.
To check for correct operation, shut off circuit breaker or discon-
nect switch to outdoor unit while it is running. Signal light on
thermostat should light. If this does not occur, check for wiring
errors or replace the service alarm.
Step 12—Outdoor Thermostat(s)
The outdoor thermostat(s) is/are installed in the control box. The
sensing bulb(s) remain/s in the control box. Outdoor thermostat
brings on stages of electric heat as outdoor temperature and
heat-pump output drops. Setting at which thermostat closes is
variable, depending on design of system. It is set at time of
installation and should not be changed without cause. Up to 2
outdoor thermostats may be installed. Some systems may not have
any thermostat. An outdoor thermostat can also be used to lock out
compressor operation at low ambients in condensing unit not
equipped with low-ambient control.
Although these devices are installed in control circuit (24v), turn
off all power to unit before attempting to troubleshoot thermostat.
Use a standard ohmmeter to check for continuity through thermo-
stat. If you suspect thermostat is out of calibration, use calibrated
electronic thermometer to determine correct outdoor temperature.
Turn thermostat dial knob until switch closes. Observe this using
ohmmeter across switch. Read temperature setting when switch
closes. It should be close to reading observed using electronic
thermometer. Any setting within ± 5°F is acceptable.
Step 13—Compressor Plug
The compressor electrical plug provides a quick-tight connection
to the compressor terminals. The plug completely covers the
THERMOSTAT
SUBBASE
24-VOLT WIRING
C
Y
L L L
C
INDOOR OUTDOOR
UNIT UNIT
TERMINAL TERMINAL
BOARD BOARD
PASS SUPPLY WIRE THROUGH
METALLIC LOOP TWICE ON
UNITS WITH NAMEPLATE
RLA OF 14 AMPS OR LESS.
Fig. 25—Service Alarm Wiring Connections
compressor terminals, and the mating female terminals are com-
pletely encapsulated in the plug. Therefore, the terminals are
isolated from any moisture so corrosion and resultant pitted or
discolored terminals are reduced. The plug is oriented to the relief
slot in the terminal box so the cover cannot be secured if wires are
not positioned in slot, assuring correct electrical connection at the
compressor. The plug can be removed by simultaneously pulling
while rocking the plug. However, these plugs are specialized and
vary in terminal orientation in the plug. Therefore, plugs can be
used on only the specific compressor or group as shown in Fig. 27.
For the Carlyle and Bristol compressors in Fig. 27, the triangle
formed by the fusite terminals points down, and the plug is
likewise oriented. The fusite terminals and plug-terminal orienta-
tion shown for the Tecumseh compressor is shown with the
triangle formed by the terminals pointing toward the top. The
configuration around the fusite terminals is the outline of the
terminal covers used on the specific compressors. The slot through
which the wires of the plug are routed is oriented on the bottom or
slightly to the left or right. The correct plug can be connected
easily to the compressor terminals and plug wires routed easily
through the slot in the terminal cover. Therefore, if a Carlyle or
Bristol compressor is substituted for a Tecumseh compressor, a
new plug must be installed. If the plug is not changed, proper
connection and routing of the plug wires through the terminal
cover will be impossible.
Step 14—Low-Voltage Terminals
The low-voltage terminal designations, along with descriptions
and/or functions, are used on all split-system condensers and heat
pumps:
G.—Energizes blower circuit from indoor thermostat.
E—Energizes emergency heat relay.
W2—Energizes first-stage supplemental heat through defrost relay
(wht).
L—Energizes light on thermostat with service alarm.
W3—Energizes second- or third-stage supplemental heat.
R—Energizes 24v power from transformer (red).
HIGH AND/OR LOW PRESSURE
AND/OR DISCHARGE TEMPERATURE
SWITCH (IF USED)
HPS
C
BRN
BLU BLU
BLK
ORN
1
SERVICE ALARM
*METALLIC
LOOP
24
DTS
LPS
YEL
YEL
YEL RED
2 3 X
ONE FIELD
LINE VOLTAGE
SUPPLY WIRE
A88340