Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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A/C Signal: Description and Operation

A/C IDLE-UP SIGNAL
The Air Conditioning (A/C) amplifier outputs an A/C idle-up signal to the Engine Control Module (ECM) when the A/C compressor clutch is in operation. The ECM will then send a signal to the Idle Speed Control (ISC) motor. This signal to the ISC motor will activate the plunger to open the throttle plate. As the throttle plate opens, the engine speed will increase slightly to prevent a rough idle or stalling condition.