Dodge ZB 2005, Руководство по обслуживанию

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(3) Connect the wire harness connectors to the
back of the A/C-heater control and install instrument
panel center bezel (Refer to 23 - BODY/INSTRU-
MENT
PANEL/INSTRUMENT PANEL CENTER
BEZEL - INSTALLATION).
A/C LOW PRESSURE SWITCH
DESCRIPTION
The A/C low pressure switch is a single pole, single
throw, pressure actuated switch that is used to con-
trol evaporator freeze up.
The A/C low pressure switch is mounted on a fit-
ting located on the top of the A/C accumulator. The
A/C low pressure switch fitting on the accumulator is
equipped with an O-ring and contains a Schrader-
type valve, which allows the switch to be serviced
without discharging the refrigerant system.
OPERATION
The A/C low pressure switch monitors the pressure
of the refrigerant leaving the accumulator to the A/C
compressor. The A/C low pressure switch is electri-
cally connected in series with the A/C high pressure
switch, between ground and the powertrain control
module (PCM). The A/C low pressure switch contact
opens or closes the path the ground, signaling the
PCM to turn the A/C compressor clutch on and off.
This regulates the refrigerant system pressure and
controls evaporator coil temperature. Controlling the
evaporator temperature prevents condensate water
on the evaporator fins from freezing and obstructing
A/C system air flow.
The A/C low pressure switch contacts open when
the suction pressure is approximately 131 to 141 kPa
(19 to 21 psi) or lower. The switch contacts close
when the suction pressure rises to approximately 241
to 269 kPa (35 to 39 psi) or above. Lower ambient
temperatures, below approximately -1° C (30° F), will
also cause the switch contacts to open. This is due to
the pressure/temperature relationship of the refriger-
ant in the system.
The A/C low pressure switch is factory-calibrated
and cannot be adjusted or repaired. If the A/C low
pressure switch is faulty or damaged, it must be
replaced.
DIAGNOSIS AND TESTING
A/C LOW PRESSURE SWITCH
NOTE: Lower ambient temperatures, below about
-1° C (30° F), during cold weather will open the
switch contacts and prevent compressor operation
due to the pressure/temperature relationship of the
refrigerant.
Before performing diagnosis of the A/C low pres-
sure switch, be certain that the switch is properly
installed on the accumulator fitting. If the switch is
not properly installed, it may not open the Schrader-
type valve in the accumulator fitting, which will pre-
vent
the switch from correctly monitoring the
refrigerant system pressure.
Verify that the refrigerant system has the correct
refrigerant charge (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM CHARGE).
(1) With gear selector in Neutral and park brake
set, start engine and allow to idle.
(2) Place the A/C-heater mode control switch in
any A/C position.
(3) Disconnect the wire harness connector from the
A/C low pressure switch.
(4) Using a suitable jumper wire, install the wire
between the two terminal cavities of the A/C low
pressure switch wire harness connector. The A/C
compressor clutch should engage.
(5) If the A/C compressor clutch does not engage,
the A/C compressor clutch, A/C compressor clutch
relay, A/C-heater mode control switch, A/C high pres-
sure switch, PCM, fuses or related wiring circuits
may be defective (Refer to 8 - ELECTRICAL/WIRING
DIAGRAM
INFORMATION - DIAGNOSIS AND
TESTING).
(6) If the A/C compressor clutch does engage, con-
nect a manifold gauge set to the low side refrigerant
system service port (Refer to 24 - HEATING & AIR
CONDITIONING
- STANDARD PROCEDURE -
REFRIGERANT SYSTEM SERVICE EQUIPMENT).
(7) Check for continuity between the two terminals
of the A/C low pressure switch. There should be con-
tinuity with a suction pressure reading of 241 to 269
kPa (35 to 39 psi) or above, and no continuity with a
suction pressure reading of 131 to 141 kPa (19 to 21
psi) or below. If OK, test and repair the A/C clutch,
A/C clutch relay, A/C-heater control, A/C pressure
transducer, PCM, fuses or related wiring circuits as
required. If not OK, replace the faulty A/C low pres-
sure switch.
REMOVAL
NOTE: Note: It is not necessary to discharge the
refrigerant system to replace the A/C low pressure
switch.
(1) Disconnect and isolate the negative battery
cable.
(2) Disconnect the wire harness connector from the
A/C low pressure switch (Fig. 12).
24 - 16 CONTROLS
ZB
A/C HEATER CONTROL (Continued)