YF7 Front and Rear Heat/A/C

YF7 Front And Rear Heat/A/C:

A switch that senses low side pressure as an indicator of the evaporator pressure controls the refrigeration cycle, or the ON and OFF operation of the compressor. The cycling pressure switch is the freeze protection device in the system. The switch also senses refrigerant pressure on the suction side of the system. This switch is located on the accumulator (6). With air temperatures of 10°C (50°F), the equalized pressures within the charged air conditioning system closes the contacts of the pressure switch.

When you select an air conditioning mode, the compressor clutch coil receives electrical energy. As the compressor reduces the evaporator pressure to approximately 159 kPa (23 psi), the pressure switch opens, de-energizing the compressor clutch. The system equalizes and the pressure reaches approximately 315 kPa (46 psi). Then, the pressure switch contacts close, re-energizing the clutch coil. The cycling continues and maintains the evaporator discharge air temperature at approximately 1°C (33°F).

Some slight increases and decreases of engine speed/power may occur under certain conditions, due to the cycling. This is normal. The system cycles in order to maintain the desired cooling, which prevents the evaporator freeze-up.

For a description of the RPO Code(s) shown in this article/image, refer to the RPO Code List found at Vehicle/Application ID Application and ID