V olvos built for the U.S. are equipped with a climate control system that comes standard in most models. The climate control system contains a function selector dial, driver and passenger temperature dials, a recirculated air switch, A/C on and off switch and a fan speed (blower motor) control switch (see Photo 1). The heater-A/C blower motor is controlled by the Electronic Climate Control (ECC) output power stage, as the air conditioning system operates only above 32° F. If the blower control switch is in the off position, the A/C compressor will not engage. Some additional components used for this type of system include a sun sensor, outside temperature sensor, low-pressure switch, interior temperature sensor, four damper door motors, high-pressure sensor, engine coolant temperature sensor and the A/C main relay.

Climate control services can range from needing to recharge the system, to performing major component repairs, such as a condenser or an evaporator replacement. This article will cover the climate control system on 850, V70 and S70 models, which are most common.

Compressor Clutch Controls
The A/C clutch is activated by the engine management system. The ECC unit requests activation using an A/C selected signal to the engine control unit via the low-pressure switch. The engine control unit (ECU) determines when the A/C compressor kicks in based on the engine temperature signal, pressure signal from ...