Where is the low pressure cut-out switch located on most A/C systems?

Where is the low pressure cut-out switch located on most A/C systems?

• A. High side vapour or high side liquid
• B. Low side suction line before evaporator
• C. In the condenser outlet
• D. At the compressor discharge line

Answer: (B)

The main idea is protecting the compressor by monitoring the suction (low-pressure) side of the system. A low-pressure cut-out switch is placed in the low-pressure refrigerant path—typically on the suction line that returns vapor to the compressor (close to the evaporator or the compressor inlet). If suction pressure drops too low, the switch opens and shuts the system down. This prevents issues like oil starvation, overheating, and compressor damage that can occur when refrigerant charge is low, a metering device is blocked, or the evaporator is iced. High-pressure safety devices are placed on the high side (after the condenser) to protect against excessive head pressure, so they serve a different protective purpose.

The main idea is protecting the compressor by monitoring the suction (low-pressure) side of the system. A low-pressure cut-out switch is placed in the low-pressure refrigerant path—typically on the suction line that returns vapor to the compressor (close to the evaporator or the compressor inlet). If suction pressure drops too low, the switch opens and shuts the system down. This prevents issues like oil starvation, overheating, and compressor damage that can occur when refrigerant charge is low, a metering device is blocked, or the evaporator is iced.

High-pressure safety devices are placed on the high side (after the condenser) to protect against excessive head pressure, so they serve a different protective purpose.