V70 XC AWD L5-2.4L Turbo VIN 56 B5254T (1998)
A/C Signal: Description and Operation
A/C Relay
A/C RELAY
The A/C Relay (2/22) is activated if the A/C switch is pressed, the Blower Fan is operating and the Engine Control Module (ECM) confirms it. Power
is supplied to the A/C Compressor Solenoid Clutch (8/3) and the cycling of the Compressor can be controlled by the Pressure Switch (Pressostat)
(7/53) in the normal way.
The Compressor is disengaged in the following circumstances to prevent it operating when full power is required, or when there is a risk of
overheating:
^ Full acceleration; when the throttle is fully open the engine control module (ECM) shuts the compressor down for a maximum of 15 seconds
and a minimum of 3 seconds.
^ Risk of overheating. If coolant temperature is above approx. 125°C the A/C compressor is prevented from operating in order to reduce engine
load and avoid further overheating.
^ If pressure exceeds approx. 3,000 kPa.
The engine control module (ECM) also prevents the compressor from engaging before the engine has started properly. The A/C compressor cannot
start until the engine has been started for approx. 5-15 seconds.
