SERVICING
10
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
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
HIGH VOLTAGE !
D
ISCONNECT
ALL
POWER
BEFORE
SERVICING
OR
INSTALLING
. M
ULTIPLE
POWER
SOURCES
MAY
BE
PRESENT
. F
AILURE
TO
DO
SO
MAY
CAUSE
PROPERTY
DAMAGE
,
PERSONAL
INJURY
OR
DEATH
.
WARNING
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 connection
on the outdoor unit PCB terminals of high pressure con-
trol, 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:
L
INE
V
OLTAGE
NOW
PRESENT
.
WARNING
3. Start the system in charge mode and place a piece of
cardboard in front of the outdoor coil, raising the con-
densing 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 pressure in Service
Problem Analysis Guide). If it cuts out below this pres-
sure 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:
L
INE
V
OLTAGE
NOW
PRESENT
.
WARNING
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 discharge
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.
If the compressor terminal PROTECTIVE COVER and
gasket (if required) are not properly in place and secured,
there is a remote possibility if a terminal vents, that the
vaporous and liquid discharge can be ignited, spouting
flames several feet, causing potentially severe or fatal injury
to anyone in its path.
This discharge can be ignited external to the compressor if
the terminal cover is not properly in place and if the
discharge impinges on a sufficient heat source.
