Dodge Nitro. Manual - part 744

and converts its data into a linear pulse width modulated (PWM) output signal which is read by the automatic 
temperature control (ATC) A/C-heater control. The ATC A/C-heater control uses the infrared sensor data as one 
of the inputs necessary to automatically control the interior cabin temperature level. By using thermal radiation 
(surface temperature) measurement, rather than an air temperature measurement, the ATC heating-A/C system 
is able to adjust itself to the comfort level as perceived by the front seat occupants. This allows the ATC system 
to compensate for other ambient conditions affecting comfort levels, such as solar heat gain or evaporative heat 
loss. 

The ATC system logic responds to the infrared sensor message by calculating and adjusting the air flow 
temperature and air flow rate needed to properly obtain and maintain the selected comfort level temperature of 
the occupants. The A/C-heater control continually monitors the infrared sensor circuit, and will store diagnostic 
trouble codes (DTCs) for any problem it detects. 

The infrared sensor is diagnosed using a scan tool (refer to HEATING & AIR CONDITIONING - 
ELECTRICAL DIAGNOSTICS for more information). 

The infrared sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged. 

REMOVAL 

SENSOR-INFRARED 

Fig. 54: Overhead Console, Screw, Infrared Sensor & Tab 
Courtesy of CHRYSLER LLC 

1. Disconnect and isolate the negative battery cable.  

2. Remove the overhead console (1) from the headliner and place it on a workbench (refer to REMOVAL ). 

NOTE:

Take the proper precautions to protect the front face of the overhead console 
from cosmetic damage while performing this procedure.

NOTE:

Typical overhead console shown.

 

2007 Dodge Nitro R/T 

2007 HVAC Heating & Air Conditioning - Service Information - Nitro

  

3. Remove the screw (2) that secures the infrared sensor (3) to the back of the overhead console and remove 

the sensor.  

INSTALLATION 

SENSOR-INFRARED 

Fig. 55: Overhead Console, Screw, Infrared Sensor & Tab 
Courtesy of CHRYSLER LLC 

1. Position the infrared sensor (3) onto the back of the overhead console (1). Align the tab (4) on the sensor 

with the slot in the console.  

2. Install the screw (2) that secures the infrared sensor(s) to the overhead console. Tighten the screw to 1.2 

N.m (10 in. lbs).  

3. Install the overhead console (refer to INSTALLATION ).  

4. Reconnect the negative battery cable.  

TRANSDUCER-A/C PRESSURE 

DESCRIPTION 

TRANSDUCER-A/C PRESSURE 

NOTE:

Take the proper precautions to protect the front face of the overhead console 
from cosmetic damage while performing this procedure.

NOTE:

Typical overhead console shown.

 

2007 Dodge Nitro R/T 

2007 HVAC Heating & Air Conditioning - Service Information - Nitro

  

Fig. 56: A/C Pressure Transducer 
Courtesy of CHRYSLER LLC 

The A/C pressure transducer (1) sends a signal to the powertrain control module (PCM) which controls both 
A/C compressor clutch engagement/disengagement and electric cooling fan operation. The A/C pressure 
transducer is mounted on a fitting located on the A/C liquid line near the dash panel. The PCM will disengage 
the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 206 kPa (30 
psi). 

The fitting for the A/C pressure transducer on the A/C liquid line is equipped with an O-ring seal and contains a 
Schrader-type valve to allow the transducer to be serviced without discharging the refrigerant system. 

OPERATION 

TRANSDUCER-A/C PRESSURE 

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its 

 

2007 Dodge Nitro R/T 

2007 HVAC Heating & Air Conditioning - Service Information - Nitro

  

connection to a fitting on the A/C liquid line. The A/C pressure transducer will change its internal resistance in 
response to the pressures it monitors. The powertrain control module (PCM) or the engine control module 
(ECM) (depending on engine application) provides a five volt reference signal and a sensor ground to the A/C 
pressure transducer, then monitors the output voltage of the A/C pressure transducer on a sensor return circuit to 
determine refrigerant pressure. The PCM/ECM is programmed to respond to the A/C pressure transducer and 
other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to 
help optimize A/C system performance and to protect the system components from damage. The PCM/ECM 
will disengage the A/C compressor clutch when high side pressure rises above 2971 kPa (431 psi) or fall below 
206 kPa (30 psi). The A/C pressure transducer input to the PCM/ECM also prevents the A/C compressor clutch 
from engaging when ambient temperatures are below about 10°C (50°F) due to the pressure/temperature 
relationship of the refrigerant. 

A Schrader-type valve in the A/C discharge line fitting permits the A/C pressure transducer to be removed or 
installed without disturbing the refrigerant in the A/C system. 

The A/C pressure transducer is diagnosed using a scan tool (refer to appropriate Engine ELECTRICAL 
DIAGNOSTICS article for more information). 

The A/C pressure transducer cannot be adjusted or repaired and it must be replaced if found inoperative or 
damaged. 

DIAGNOSIS AND TESTING 

TRANSDUCER-A/C PRESSURE 

The A/C pressure transducer is tested using a scan tool (refer to appropriate Engine ELECTRICAL 
DIAGNOSTICS article for more information). Before testing the A/C pressure transducer, be certain that the 
transducer wire harness connection is clean of corrosion and properly connected. For the A/C to operate, an A/C 
pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range 
indicate a low or high refrigerant system pressure condition to the powertrain control module (PCM). The PCM 
is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the A/C 
compressor. Refer to the A/C Pressure Transducer Voltage chart for the possible conditions indicated by the 
transducer voltage reading. 

A/C PRESSURE TRANSDUCER VOLTAGE 

Voltage 

Possible Indication 

0.0

1. No sensor supply voltage from PCM.
2. Shorted sensor circuit.
3. Inoperative transducer.

0.150 TO 0.450

1. Ambient temperature below 10°C (50°F).
2. Low refrigerant system pressure.

0.451 TO 4.519

1. Normal refrigerant system pressure.

4.520 TO 4.850

1. High refrigerant system pressure.

5.0

1. Open sensor circuit.
2. Inoperative transducer.

 

2007 Dodge Nitro R/T 

2007 HVAC Heating & Air Conditioning - Service Information - Nitro