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Testing Regina ECU inputs from A/C 700 1990

Hi,
I'm struggling (still) with low idle speed when the transmission is in drive and the A/C is on. Off idle there is no problem, it's only a problem when at idle. The car idles steadily in this condition, just at too low a speed which makes the car chatter and somewhat uncomfortable for the passengers. Switching the car to park, or switching off the A/C compressor, eliminates the chatter, but it's a little bit much to constantly do this in stop-and-go traffic.

It looks like there are two inputs from the A/C to the Regina: 1) from the dashboard switch (to tell the ECU the A/C switch is on), and 2) from the compressor (to tell the ECU that the compressor is engaged).

Can the Mode-3 diagnostics in LH2.4 be used to test both inputs? Or just the former? It looks to me like "just the former".

Can input #2 possibly assert itself before the pulley is turning, i.e. the engine is running?

ed







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