Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Dual Pressure Switch
Dual pressure switch, located on compressor manifold, monitors refrigerant pressure. This information is sent to Powertrain Control Module (PCM), which uses this information to control cooling fan and A/C compressor clutch.
When discharge pressure decreases to about 250 psi (17.5 kg/cm2 ), dual pressure switch contacts will close, energizing A/C compressor (magnetic) clutch coil. When discharge pressure increases to about 405-445 psi (28.5-31.3 kg/cm2 ), dual pressure switch contacts will open, de-energizing A/C compressor clutch coil.
When A/C is turned on, cooling fan operates at low speed. When discharge pressure is about 305-345 psi (21.4-24.3 kg/cm2 ), dual pressure switch contacts will close and cooling fan will operate at high speed. When discharge pressure decreases to 230-270 psi (16.2-19.0 kg/cm2 ), dual pressure switch contacts will open and cooling fan will operate at low speed.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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