XC70 AWD L6-3.2L VIN 98 B6324S (2009)
The function of the leak diagnostic unit is to pressurize the fuel tank system during leak diagnostics and to open the fuel tank system to the surrounding
air during evaporative emissions control.
The leak diagnostic unit consists of a plastic housing with:
1. electrical air pump
2. a valve / solenoid which governs the air flow in the unit
3. a heater element (PTC resistor) which warms up the pump.
The electrical pump, valve and heater element in the unit are supplied with voltage by the system relay. The pump, valve and heater element are
grounded (control) in the engine control module (ECM).
During leak diagnostics the pump in the leak diagnostic unit starts. The valve in the unit is operated by the engine control module (ECM) by grounding
the different circuits internally in the engine control module (ECM). Operation depends on whether the diagnostic phase is checking for leakage or
checking the function of the diagnostic system. The engine control module (ECM) gauges the power consumption of the pump during pressurization. The
power consumption corresponds to a certain pressure in the fuel tank system. See also: Leak diagnostics (certain markets only) See: Powertrain
Management/Computers and Control Systems/Description and Operation/Leak Diagnostics (Certain Markets Only)
The engine control module (ECM) can diagnose the leak diagnostic unit.
The valve in the leak diagnostic unit can be activated and the power consumption of the pump can be read off.
The leak diagnostic unit is at the upper front edge of the fuel tank.
air conditioning (A/C) compressor.
The air conditioning (A/C) compressor transports refrigerant, which is necessary for air conditioning (A/C) operation. It is an axial piston compressor
with variable displacement. I.E. The compressor has adjustable cylinder displacement which is controlled by a check valve (solenoid). The valve, which
is underneath the compressor, can be replaced.
The A/C compressor is mounted on the cylinder block and is driven by the engine's crankshaft via the auxiliaries belt.
For further information, see Design and Function, climate control module (CCM).
Air conditioning (A/C) relay