Dodge Neon / Neon SRT-4. Manual - part 428
A/C LOW PRESSURE SWITCH
DESCRIPTION
The A/C low pressure switch is a single pole, single
throw, pressure actuated switch that is installed in a
threaded port into the suction passage of the accu-
mulator on 2.0L LHD models or in a threaded port
into the suction passage of the expansion valve on
2.4L and RHD models. The accumulator fitting on
2.0L LHD models contain a Schrader type valve,
which allows the switch to be serviced without dis-
charging the refrigerant system and is equipped with
a O-ring to seal the switch plumbing connection. The
A/C low pressure switch on 2.4l and RHD models can
only be serviced with the refrigerant system dis-
charged.
The A/C low pressure switch is factory calibrated
and cannot be adjusted or repaired and, if faulty or
damaged, it must be replaced.
OPERATION
The A/C low pressure switch is electrically con-
nected in series with the A/C-heater control mode
switch and 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 temper-
ature prevents condensate water on the evaporator
fins from freezing and obstructing air conditioning
system air flow.
On 2.0L LHD models, the A/C low pressure switch
contacts are open when the suction pressure is
approximately 152 kPa (22 psi) or lower. The switch
contacts will close when the suction pressure rises to
approximately 234 to 262 kPa (34 to 38 psi) or above.
Lower ambient temperatures, below approximately
-1° C (30° F), will also cause the A/C low pressure
switch contacts to open. This is due to the pressure/
temperature relationship of the refrigerant in the
system.
On 2.4L and RHD models, the A/C low pressure
switch contacts are open when the suction pressure
is approximately 96 kPa (14 psi) or lower. The switch
contacts will close when the suction pressure rises to
approximately 234 to 262 kPa (34 to 38 psi) or above.
DIAGNOSIS AND TESTING
A/C LOW PRESSURE SWITCH
NOTE: Lower ambient temperatures, below about
-1° C (30° F), during cold weather will open the A/C
low pressure switch contacts and prevent A/C com-
pressor operation due to the pressure/temperature
relationship of the refrigerant.
Before performing diagnosis of the A/C low pres-
sure switch, verify that the refrigerant system has
the correct refrigerant charge (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE) and that the A/C low pressure switch is
properly installed on the accumulator fitting. If the
A/C low pressure switch is not properly installed, it
may not open the Schrader-type valve in the accumu-
lator fitting, which will prevent the switch from cor-
rectly monitoring the refrigerant system pressure.
For circuit descriptions and diagrams, refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, further details on wire
harness routing and retention, as well as pin-out and
location views for the various wire harness connec-
tors, splices and grounds.
(1) With gear selector in Park or Neutral and with
park brake set, start the engine and allow it to idle.
(2) Place the A/C-heater mode control 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
jumper wire between the two terminals of the wire
harness connector for the A/C low pressure switch.
The A/C compressor clutch should engage. If the A/C
clutch does engage, replace the faulty A/C low pres-
sure switch. If the A/C clutch does not engage, the
A/C clutch, A/C clutch relay, A/C-heater control, A/C
high pressure switch, PCM or ECM (depending on
engine application), fuses or related wiring circuits
may be defective (Refer to 8 - ELECTRICAL/WIRING
DIAGRAM
INFORMATION
-
DIAGNOSIS AND
TESTING). Repair as required.
REMOVAL
2.0L LHD MODELS
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. 14).
(3) Remove the A/C low pressure switch from the
fitting on the top of the accumulator.
(4) Remove the O-ring seal from the accumulator
and discard.
24 - 20
CONTROLS
PL/SRT-4