A/C Switches
High and low pressure switches protect the A/C system and trigger the compressor clutch based on system pressure.
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High and low pressure switches protect the A/C system and trigger the compressor clutch based on system pressure.
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A/C pressure switches protect the system by monitoring refrigerant pressure and cutting power to the compressor if pressure goes out of range. A faulty pressure switch can cause the A/C to stop working entirely even when the system has adequate refrigerant — making it one of the most misdiagnosed A/C components on semi trucks.
At True Truck Parts, we carry OEM-spec A/C pressure switches for Freightliner, Kenworth, Peterbilt, Volvo, Mack, and International trucks. Serving fleets in Mississauga, Brampton, Vaughan, Milton, Oakville, Burlington, and across the GTA. Same-day quoting, Canada-wide delivery.
The A/C pressure switch monitors refrigerant pressure on the high and low sides of the system. If pressure drops too low (refrigerant leak) or rises too high (blockage or overcharge), the switch cuts power to the compressor clutch to prevent damage. A faulty switch can falsely trigger this cutoff even when the system pressure is within normal range.
With the system at operating pressure, use a multimeter to check continuity across the switch terminals. A good switch shows continuity (closed circuit) within its rated pressure range. You can also temporarily bypass the switch to see if the compressor engages — if it does and the system has proper refrigerant, the switch is faulty and needs replacement.
Yes — high-pressure switches, low-pressure switches, and combination dual-pressure switches. Some trucks also use a binary switch (shuts off below low-pressure and above high-pressure threshold) or a trinary switch that also controls the condenser cooling fan. Contact us to confirm the correct switch type for your specific truck make and model.
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