SERVICING
10
1. Remove control panel cover, or etc., to gain access to
transformer.
With power ON:
WARNING
Line voltage now present.
2. Using a voltmeter, check voltage across secondary
voltage 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
voltage connections and/or splices.
5. If line voltage available at primary voltage side of
transformer and wiring and splices good, transformer
is inoperative. Replace.
CHECKING HIGH PRESSURE SWITCH
WARNING
HIGH VOLTAGE
Disconnect ALL power before servicing or in-
stalling this unit. Multiple power sources may
be present. Failure to do so may cause proper-
ty damage, personal injury or death.
The high pressure switch senses the pressure in the com-
pressor discharge line. If abnormally high condensing pres-
sures develop, the contacts of the control open, breaking
the control circuit before the compressor motor overloads.
This control is automatically reset.
1. Using an ohmmeter, check across the X32A connec-
tion on the outdoor unit PCB terminals of high pres-
sure control, with wire removed. If not continuous, the
contacts are open.
2. Attach a gauge to the dill valve port on the base
valve.
With power ON:
WARNING
Line voltage now present.
3. Start the system in charge mode and place a piece
of cardboard in front of the outdoor coil, raising the
condensing pressure.
4. Check pressure at which the high pressure control
cuts-out. If it cuts-out at 605 PSIG to -17 PSIG, it is
operating normally (See causes for high head pres-
sure in Service Problem Analysis Guide). If it cuts out
below this pressure range, replace the control.
CHECKING INDOOR AND OUTDOOR HI/LOW PRES-
SURE SENSOR
The HI/LOW pressure sensor senses the suction pressure in
cooling mode, and the discharge pressure in heating mode.
Follow the following sequence to check the pressure sensor.
With Power ON:
WARNING
Line voltage now present.
1. Connect manifold gauge to the air conditioner unit
2. Connect a pair of extended Molex probe tips to your
voltmeter test leads.
3. Find the suction pressure in the cool mode, or dis-
charge pressure in the heat mode (terminals) Locate
(X17A) connection and connect a DC voltmeter
across sensor terminals 1 and 3, (black and white
wires) and record the DC voltage.
4. Compare your readings to the detected pressure vs
output voltage in the following table. Replace the
sensor if the sensor is open, shorted, or outside of the
voltage range.
-200
-100
0
100
200
300
400
500
600
700
800
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
De
tec
ted
P
res
su
re (
PSI
G)
Output Voltage (DCV)
VOLTAGE AND PRESSURE CHARACTERISTICS
CHECKING COMPRESSOR
WARNING
Hermetic compressor electrical terminal venting can
be dangerous. When insulating material which supports
a hermetic compressor or electrical terminal suddenly
disintegrates due to physical abuse or as a result of an
electrical short between the terminal and the compressor
housing, the terminal may be expelled, venting the vapor and
liquid contents of the compressor housing and system.
