AC Pressure Sensor

Replace the AC pressure sensor on a 1992 Dodge Viper V10, which monitors refrigerant pressure and protects the compressor from operating under unsafe conditions.

Warnings

Tools required

Parts

• AC pressure sensor/switch × 1 — Use OEM specification
• AC line O-rings × 2 — Use OEM specification

Fluids

• R-12 refrigerant
• PAG oil for AC system

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine to cool completely if recently driven
3. Have AC system refrigerant professionally recovered by certified technician or using approved recovery equipment
4. Verify system pressure is at 0 PSI before proceeding

Procedure

1. 1

   Locate AC pressure sensor
   Open the hood and locate the AC pressure sensor on the high-side AC line near the firewall on the passenger side of the engine bay. The sensor is a cylindrical switch threaded into the AC line with a 2-pin electrical connector. It is typically positioned on the liquid line between the condenser and the evaporator.
2. 2

   Disconnect pressure sensor electrical connector
   Press the tab on the 2-pin electrical connector and pull it straight off the pressure sensor. Route the connector away from the work area to prevent damage.
3. 3

   Remove AC pressure sensor
   Using a 19mm wrench or crowfoot wrench, unthread the pressure sensor from the AC line fitting in a counterclockwise direction. Remove the sensor completely and set aside. Some residual oil may drip from the fitting; this is normal.
4. 4

   Inspect and replace O-rings
   Remove the old O-ring from the sensor port on the AC line. Inspect the sealing surface for damage or debris. Install a new O-ring onto the new pressure sensor, then lightly coat the O-ring with fresh PAG oil to ensure proper sealing and prevent damage during installation.
5. 5

   Install new AC pressure sensor
   Thread the new AC pressure sensor into the AC line fitting by hand in a clockwise direction until hand-tight. Use the 19mm wrench to tighten the sensor to the OEM-specified torque (verify exact value; AC pressure sensors are typically low torque, approximately 7-11 Nm / 5-8 lb-ft). Do not overtighten. Do not overtighten, as this can damage the fitting or crack the sensor body.
   Torque spec

   AC Line Fittings27 Nm (20 lb-ft)
6. 6

   Reconnect electrical connector
   Push the 2-pin electrical connector firmly onto the new pressure sensor until it clicks into place. Verify the connector is fully seated and the locking tab is engaged.
7. 7

   Evacuate and recharge AC system
   Using AC service equipment, evacuate the system to remove air and moisture (minimum 30 minutes vacuum hold). Verify the system holds vacuum without loss. Recharge the AC system with the specified amount of R-134a refrigerant according to the underhood AC specification label.

Reassembly

1. No disassembly was required beyond component removal
2. Ensure all electrical connections are secure and properly routed
3. Close hood after verifying no tools or parts are left in engine bay

Verification

• Start the engine and turn on the AC system to maximum cool
• Verify the AC compressor engages and disengages normally
• Check for refrigerant leaks around the pressure sensor fitting using a leak detector
• Verify cold air output from cabin vents
• Monitor AC system pressure readings to confirm proper operation (typical high-side pressure 150-250 PSI at idle with ambient temperature 70-90°F)
• Verify no warning lights or fault codes are present

Related trouble codes on this vehicle

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