Section 22: HEATING AND AIR CONDITIONING
PA1553
11
NOTE
When starting the A/C compressor wait 5
seconds before checking pressures in order to
give the system a chance to build its pressure.
During the first 5 seconds after startup, the
compressor is active on 6 cylinders and the
A/C valve is open regardless of the pressure
readings.
In test mode, with the parking brake applied and
the passenger set point set to a value higher
than 64°F (18°C), the hot water circulating pump
is not set to OFF as it would normally do when
the outside temperature gets above 50°F
(10°C). This feature allows verification of the
pump when inside a garage. This is also useful
when working on the heating system to remove
air pockets trapped in the system.
When performing an A/C cooling test and having
the water pump shut off in switch/sensor test
mode is required, just set the passenger set
point temperature to the minimum 64°F (18°C)
to shut off the pump.
7.2 HVAC SYSTEM AND TEST MODE FOR
ELECTRIC MOTORS
The test mode allows testing the motors and
electric contactors without the need to have the
engine running (see Section 06: ELECTRICAL
under "TEST MODE FOR ELECTRICAL
MOTORS" for complete information).
Use this test mode for testing of the condenser
motors, the A/C compressor clutch activation,
left and right unloaders, evaporator motor, water
pump, and hot water solenoid valve.
7.3 PARTICULARITIES
Conditions for engaging the
2
nd
speed on the evaporator
motor (cooling demand).
The 2
nd
speed engages if the cabin area air temperature is 1 degree
above the set point and it revert to speed 1 if the temperature gets
equal or below the set point.
Conditions for hot water
recirculating pump activation
(heating demand).
The pump turns to OFF if the outside temperature is above 50°F
(10°C), when there is less demand for heating.
Note: To test a working pump, it is possible to keep it active even if
the outside temperature is above 50°F (10°C). See paragraph 7.2
HVAC SYSTEM AND TEST MODE FOR ELECTRIC MOTORS.
The compressor unloaders are
working based on pressure
and also on the difference
between the cabin area air
temperature and the set point.
2 left compressor cylinders:
Stop if: Cabin area air temperature is at less than 0.4°C degree above
the set point or if the compressor output is above 280 psi, or if the
compressor input is below 26 psi.
Restart if: Cabin area air temperature is 0.9°C or more above the set
point and the compressor pressure output is less than 220 psi and the
compressor pressure input is above 34 psi.
2 right compressor cylinders:
Stop if: Cabin area air temperature is at less than 0.2°C above the set
point or if the compressor input falls below 23 psi.
Restart if: Cabin area air temperature is 0.7°C or more above the set
point and the compressor input pressure is above 32 psi.
The A/C deactivation pressure
is 320 psi.
In case of high pressure, the analog pressure sensor connected to
the Multiplex module deactivates the compressor.
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