Recirculation control (electronic climate control only)

Fig 1: Recirculation Control Input And Output Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.

The climate control module (CCM) (3/112) controls the recirculation during the following conditions for electronic climate control:

• The recirculation switch is on (the LED lights orange)
• The system is in AUTO position and there is a large difference between the desired and current temperature
• The car is equipped with an air quality sensor, and the recirculation switch is on (the LED light green).

The air quality sensor transmits a signal to the climate control module (CCM) if it detects high concentrations of pollutants in the outside air. When this occurs the climate control module (CCM) transmits a signal to the damper motor for recirculation (6/48) to close the fresh air damper and to use recirculated air. The level of recirculation is controlled by the signal from the air quality sensor:

• signal 1 provides partial recirculation for speeds below 85 km/h, no recirculation for speeds exceeding 85 km/h
• signals 2 and 3 provide 100% recirculation.

If the high level of pollutants remains the system stays in recirculation for a certain time, maximum of 10 minutes. The time that the system is recirculating is determined by the outside temperature, if the air conditioning (A/C) is on and if the windshield wipers are activated. The system returns to fresh air for a short time before recirculation is resumed. The particle filter absorbs most of the pollutants entering the passenger compartment during this time. The maximum time prevents misting and musty air.

The air quality transmits information about the content of pollutants to the climate control module (CCM). This information is graded into four levels, and the information used for diagnosis.

Recirculation is never permitted if the defroster is selected. The climate control module (CCM) requests the compressor when the evaporator temperature exceeds 3 °C.