A/C Pressure Switch

WARNING: This page is about a different car, the 2006 Honda Odyssey and 2005 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.

The A/C pressure switch consists of a high-low pressure switch (A/C pressure switch A) and a middle pressure switch (A/C pressure switch B).

High-low pressure switch
If the refrigerant pressure becomes too high (due to blockage or lack of airflow at the condenser), or too low (due to leakage), the A/C pressure switch stops the A/C request signal to the PCM and the A/C compressor stops operating.

Fig 1: A/C High-Low Pressure Switch Operation
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Middle pressure switch
If the refrigerant pressure goes above 1,520 kPa (15.5 kgf/cm² , 221 psi), the A/C pressure switch closes to signal the PCM to change the speed of the A/C condenser fan and radiator fan to high. When the refrigerant pressure drops below 1,230 kPa (12.5 kgf/cm² , 178 psi), the A/C pressure switch opens to signal the PCM to change the speed of the A/C condenser fan and radiator fan to low.

Fig 2: A/C Middle Pressure Switch Operation
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 3: Identifying Air Flow System Description (1 Of 2)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Identifying Air Flow System Description (2 Of 2)
Courtesy of AMERICAN HONDA MOTOR CO., INC.