Vanden Plas (X300) L6-4.0L (AJ16) (1996)
Control Module HVAC: Description and Operation
Engine Speed Signal
Engine Speed Signal
The Air Conditioning Control Module (A/CCM) receives an engine speed signal from the Engine Control Module (ECM).
This signal facilitates compressor lock sensing (12 cyl. vehicles only).
This signal also aids the A/CCM inhibition of the heated screen relays. At engine speeds lower than 800 RPM the A/CCM assumes poor idle or engine
not running and will not permit the selection of the heated screens.