Control; Refrigerant Pressure Switch; Low / High Pressure Switch - Mazda CT-L1005 Training Manual

A/C System

Control

Refrigerant Pressure Switch

•
The triple-type refrigerant pressure switch is located on the high-pressure side of the A/C
system, and consists of the low and high pressure switch and the medium pressure
switch.

Low / High Pressure Switch

•
The low / high-pressure switch protects the A/C system by outputting an A/C cut-off
signal to the PCM (Powertrain Control Module) when the pressure in the system is
abnormally low or high. The PCM then controls the magnetic clutch through the A/C
relay to shut the compressor off in the event of too little or too much pressure in the
system.
•
When the pressure in the A/C system is either too low or too high, it can cause damage
to the rest of the system. For example when the pressure is too low, there will be less
refrigerant delivered to the compressor. Because the compressor oil is carried along with
the refrigerant, this means that the compressor could be starved of lubrication, and
damage could result. When too much pressure develops in the system there could be a
rupture in a component (e.g. at a line or a connection). If this were allowed to happen, it
might cause injury or damage to other components.
NOTE: The A/C circuit is equipped with a fusible plug to protect the system against
excessive pressure (in case the magnetic clutch cannot be disengaged because of a
malfunction). If the pressure in the A/C system becomes too high, the plug opens
and refrigerant is released to the atmosphere.
03-20
Basic Climate Control
Curriculum Training
L1005_060