Jeep Cherokee 2000 Service Manual - page 1880
(2) Place the heater-A/C mode control switch knob
in each mode position, one position at a time, and
pause after each selection. The test set gauge should
return to the 27 kPa (8 in. Hg.) setting shortly after
each selection is made. If not OK, a component or
vacuum line in the vacuum circuit of the selected
mode has a leak. See the procedure in Locating Vac-
uum Leaks.
CAUTION: Do not use lubricant on the switch ports
or in the holes in the plug, as lubricant will ruin the
vacuum valve in the switch. A drop of clean water
in the connector plug holes will help the connector
slide onto the switch ports.
LOCATING VACUUM LEAKS
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
TO
GROUP
8M
-
PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
STEERING
COLUMN,
OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect
the
vacuum
harness
connector
behind the glove box and inboard of the glove box
opening on the heater-A/C housing.
(2) Connect the test set vacuum hose probe to each
port in the heater-A/C housing half of the vacuum
harness connector, one port at a time, and pause
after each connection (Fig. 10). The test set gauge
should return to the 27 kPa (8 in. Hg.) setting
shortly after each connection is made. If OK, replace
the faulty heater-A/C control. If not OK, go to Step 3.
(3) Determine the vacuum line color of the vacuum
circuit that is leaking. To determine the vacuum line
colors, refer to the Vacuum Circuits chart (Fig. 11) or
(Fig. 12).
(4) Disconnect and plug the vacuum line from the
component (fitting, actuator, valve, switch, or reser-
voir) on the other end of the leaking circuit. Instru-
ment panel disassembly or removal may be necessary
to gain access to some components. See the service
procedures in this group.
(5) Connect the test set hose or probe to the open
end of the leaking circuit. The test set gauge should
return to the 27 kPa (8 in. Hg.) setting shortly after
each connection is made. If OK, replace the faulty
disconnected component. If not OK, go to Step 6.
(6) To locate a leak in a vacuum line, leave one
end of the line plugged and connect the test set hose
or probe to the other end of the line. Run your fin-
gers slowly along the line while watching the test set
gauge. The vacuum reading will fluctuate when your
fingers contact the source of the leak. To repair the
vacuum line, cut out the leaking section of the line.
Then, insert the loose ends of the line into a suitable
length of 3 millimeter (0.125 inch) inside diameter
rubber hose.
SERVICE PROCEDURES
REFRIGERANT OIL LEVEL
When an air conditioning system is assembled at
the factory, all components except the compressor are
refrigerant oil free. After the refrigerant system has
been charged and operated, the refrigerant oil in the
compressor is dispersed throughout the refrigerant
system. The accumulator, evaporator, condenser, and
compressor will each retain a significant amount of
the needed refrigerant oil.
It is important to have the correct amount of oil in
the refrigerant system. This ensures proper lubrica-
tion of the compressor. Too little oil will result in
damage to the compressor. Too much oil will reduce
the cooling capacity of the air conditioning system.
It will not be necessary to check the oil level in the
compressor or to add oil, unless there has been an oil
loss. An oil loss may occur due to a rupture or leak
from a refrigerant line, a connector fitting, a compo-
nent, or a component seal. If a leak occurs, add 30
milliliters (1 fluid ounce) of refrigerant oil to the
refrigerant system after the repair has been made.
Refrigerant oil loss will be evident at the leak point
by the presence of a wet, shiny surface around the
leak.
Refrigerant oil must be added when a accumulator,
evaporator coil, or condenser are replaced. See the
Refrigerant Oil Capacities chart. When a compressor
Fig. 10 Vacuum Circuit Test
XJ
HEATING AND AIR CONDITIONING
24 - 19
DIAGNOSIS AND TESTING (Continued)