hvac

AC Low Pressure Switch

for 2017 Dodge Viper 8.4L V10 · RWD

Difficulty

Moderate

Time

36 min

Tools

Steps

✓Fact-checked. Built from OLP's spec database, then independently fact-checked line by line with every correction applied. Master-tech sign-off by Chris Hackleman is queued. Cross-check torque values against the factory manual, and stop if anything looks unsafe. How our data is made.

Replace the AC low pressure switch on the 2008 Dodge Viper 8.4L V10 by accessing it on the AC line near the accumulator/drier, discharging the system, disconnecting the electrical connector, and installing the new switch.

Warnings

⚠️AC system is under high pressure. Always recover refrigerant using proper equipment before opening any AC lines or components. Refrigerant can cause frostbite on contact with skin.

⚠Only certified technicians should handle AC refrigerant recovery and recharging. Improper handling violates EPA regulations.

⚠Wear safety glasses and gloves when working with AC system components.

ℹ️The AC system must be evacuated and recharged after switch replacement. Factor in additional time for these procedures.

Tools required

AC refrigerant recovery machineEssential

Socket set (metric)Essential

Torque wrench

Adjustable wrench or line wrenchEssential

AC vacuum pumpEssential

AC manifold gauge setEssential

Safety glassesEssential

Work glovesEssential

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Parts

AC low pressure switch × 1 — Use OEM specification
O-ring seals for switch (if not included with switch) × 1 — Use OEM specification

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Fluids

R-134a

Preparation

Park vehicle on level surface and engage parking brake
Allow engine to cool completely if recently driven
Ensure AC system is off
Gather all tools and replacement parts before beginning

Procedure

1
Recover AC refrigerant
Connect AC recovery machine to the service ports on the AC system. Follow manufacturer instructions to fully recover all R-134a refrigerant from the system. Record the amount recovered for recharging reference. This is a legal requirement and prevents refrigerant release into the atmosphere.
2
Locate AC low pressure switch
Open the hood and locate the AC low pressure switch. On the 2008 Viper 8.4L V10, the low pressure switch is mounted on the AC line/component in the engine bay. Verify the exact switch location against the factory service manual, as this system uses a receiver/drier (not an accumulator). The switch has a single electrical connector and threads into the AC line.
3
Disconnect electrical connector
Press the release tab on the electrical connector for the low pressure switch and pull the connector straight off the switch. Move the wiring harness aside to provide clearance for switch removal.
4
Remove low pressure switch
Using an adjustable wrench or appropriate line wrench, unthread the low pressure switch from the AC line fitting by turning counterclockwise. Be prepared for a small amount of residual refrigerant oil to leak from the port. Remove the switch completely and inspect the O-ring seal that came off with it.
5
Prepare new switch for installation
Remove the new low pressure switch from packaging. Check that it includes a new O-ring seal. If a separate O-ring is provided, lubricate it lightly with clean refrigerant oil and install it onto the threads of the new switch. If the switch comes with a pre-installed O-ring, verify it is in good condition.
6
Install new low pressure switch
Thread the new low pressure switch into the AC line fitting by hand, turning clockwise until hand-tight. Using the wrench, tighten the switch securely. Tighten firmly to ensure a leak-free seal, but do not overtighten as this can damage the fitting or crush the O-ring. Tighten the switch to the factory-specified torque value; refer to the factory service manual for the exact specification.
7
Reconnect electrical connector
Push the electrical connector firmly onto the new low pressure switch terminal until it clicks into place. Verify the connector is fully seated and the locking tab is engaged.
8
Evacuate AC system
Connect AC vacuum pump to the system service ports. Evacuate the system for a minimum of 30 minutes to remove all air and moisture. Monitor the vacuum gauge to ensure the system holds vacuum, which indicates no leaks are present at the new switch installation.
9
Recharge AC system
Using the AC manifold gauge set and refrigerant source, recharge the system with R-134a refrigerant to the factory specified amount (refer to the underhood emissions/AC label for exact capacity). Monitor pressure gauges during charging to ensure proper fill. The low pressure switch controls compressor operation based on system low-side pressure; refer to the factory service manual for the exact cut-in/cut-out pressure specifications.

Reassembly

Verify electrical connector is fully seated and locked
Ensure no tools or parts are left in engine bay
Close hood after final inspection

Verification

Start engine and turn AC system to maximum cooling
Verify compressor cycles on and off as controlled by the low pressure switch
Check for cold air output from cabin vents
Inspect the low pressure switch installation area for any signs of refrigerant leakage (oil residue)
Use AC leak detector or soapy water solution around switch threads to verify no leaks
Monitor AC system operation for several minutes to confirm proper cycling and cooling performance