Dodge Dakota 2001, Service Manual

Page: 2183 / 2307

(3) Connect the high side manifold gauge set to
the fitting on the liquid line high side refrigerant
system service port.
(4) Compare the DRBIII
t
pressure value to the
manifold gauge set reading. The pressure reading
from the DRBIII
t
should be similar to the reading of
the manifold gauge set value.
(5) If not, replace the a/c pressure transducer.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the wire harness connector from the
A/C pressure transducer, which is mounted to a fit-
ting on the liquid line between the condenser and the
high side service port.
(3) Unscrew the A/C pressure transducer from the
discharge line fitting.
(4) Remove the A/C pressure transducer from the
vehicle.
(5) Remove the O-ring seal from the discharge line
fitting and discard.
INSTALLATION
(1) Lubricate a new O-ring seal with clean refrig-
erant oil and install it on the discharge line fitting.
Use only the specified O-rings as they are made of a
special material for the R-134a system. Use only
refrigerant oil of the type recommended for the com-
pressor in the vehicle.
(2) Install and tighten the A/C pressure transducer
on the discharge line fitting.
(3) Plug the wire harness connector into the A/C
pressure transducer.
(4) Connect the battery negative cable.
AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the com-
pass mini-trip computer module through the ambient
temperature sensor. The ambient temperature sensor
is a variable resistor mounted to a bracket that is
secured with a screw to the right side of the radiator
yoke, behind the radiator grille and in front of the
engine compartment.
For complete circuit diagrams (Refer to 8 - ELEC-
TRICAL/WIRING DIAGRAM INFORMATION -
DIAGNOSIS AND TESTING). The ambient tempera-
ture sensor cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the HVAC control head unit. The resis-
tance in the sensor changes as temperature changes,
changing the temperature sensor signal circuit volt-
age to the HVAC control head unit. Based upon the
resistance in the sensor, the HVAC control head unit
senses a specific voltage on the temperature sensor
signal circuit, which it is programmed to correspond
to a specific temperature.
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR
The thermometer function is supported by the
ambient temperature sensor, a wiring circuit, and a
portion of the HVAC control. If any portion of the
ambient temperature sensor circuit fails or if PCI
Bus information is missing, a (– –) will appear in the
display in place of the temperature, when the sensor
is exposed to temperatures above 55° C (140° F), or if
the sensor circuit is shorted. A (– –) will appear in
the display in place of the temperature, when the
sensor is exposed to temperatures below - 40° C (-
40° F), or if the sensor circuit is open.
The ambient temperature sensor circuit can also be
diagnosed using the following Sensor Test, and Sen-
sor Circuit Test. If the temperature sensor and cir-
cuit are confirmed to be OK, but the temperature
display is inoperative or incorrect, refer to Diagnosis
and Testing the Compass Mini-Trip Computer in
this section. For complete circuit diagrams, refer to
Wiring Diagrams.
SENSOR TEST
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor harness
connector.
(2) Measure the resistance of the ambient temper-
ature sensor. At - 40° C (- 40° F), the sensor resis-
tance is 336 kilohms. At 55° C (140° F), the sensor
resistance is 2.488 kilohms. The sensor resistance
should read between these two values. If OK, refer to
Sensor Circuit Test in the Diagnosis and Testing
section of this group. If not OK, replace the faulty
ambient temperature sensor.
SENSOR CIRCUIT TEST
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector and the HVAC control harness con-
nector.
(2) Connect a jumper wire between the two termi-
nals in the body half of the ambient temperature sen-
sor harness connector.
(3) Check for continuity between the sensor return
circuit and the ambient temperature sensor signal
24 - 18 CONTROLS
AN
A/C PRESSURE TRANSDUCER (Continued)