Just4Fun

1995 Miata with MS3Pro PNP the a/c clutch engages, but the A/C Fan does not engage. Idle up works fine and main fan kicks on below Fan Control Temps. Just need the A/C to come on so I can cruise.

I started by removing the A/C relay and it bench tested fine. Energized properly with good continuity through the relay.

While the engine was running and the A/C compressor running I tested the wiring inputs to the relay. Both power wires to the hot side relay(BLU/Y) and solenoid wire (BLK/WHT) were showing 12+V. When I attached the BLU/WT wire to the relay, it did not energize the relay solenoid.

I checked the BLU/WT for ground and it was open. I've reviewed both the Miata stock wiring diagram and Megasquirt documentation and can find no control or I/O for this part of the circuit.

Does MS3Pro PNP control this circuit?

Appreciate any insight before I start inventing work arounds.

Yours truly,
Just4Fun....Smitty

cpierr03

If I recall the default control outputs are swapped, I believe Inj J controls the compressor clutch and Inj I controls the passenger side fan.

Just4Fun

Thank you for your insight. I will try a test mode for those outputs and see what happens.

Just4Fun

cpierr...well the hint paid off. Inj I was not assigned in the I/O pins. Ran a test mode on that I/O and the ac fan relay buzzed. Went into advanced setting/programmable I/O and set Inj I to reference coolant sensor such that it turns on at 80 degrees +- 3 degrees and fan kicked on. Reset the reference to >199 degrees.

Hit the highway with A/C, hwy temps at 95, engine held temps between 203 and 204 for 30 min at 70 mph.

Thanks again for the hint!

Just4Fun

cpierr03

Yep, I had the same problem, just couldn't remember how I fixed it . Glad you got it sorted!