Operation CHARM: Car repair manuals for everyone.
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)

Or, hide this message: temporarily or permanently

ECM A/C Load Logic

ECM A/C Load Logic

1. Check coolant temperature. Coolant must be above 167° F before continuing.

2. With transmission in Park, turn on the A/C. The engine speed will increase (From 1,000 to 1,500 RPM), then decrease back to normal (From 750 RPM).

3. Leave engine idling for 10 minutes.

4. Turn engine off and wait 10 seconds (for ECM relay to go off). Restart the engine and confirm the engine does not surge when A/C is turned on. Repeat steps 1 - 3 if surge is still present.

5. Drive vehicle with A/C on to confirm surge is not present when A/C compressor engages. Repeat steps 1-3 if surge is still present.