So I'm swapping an 99 interior into my NA (I know the dash is heavier) but I'm stuck with wiring the HVAC. I found this thread on m.net but I just don't understand it. Hopefully someone here does.

NB HVAC controls INSTALLED in NA - MX-5 Miata Forum
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So far I've got the lights to work and the fan to work in all 4 speeds. The a/c compressor isn't kicking on though.
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The a/c switch completes a ground. Add a ground jumper and see what happens.

 

To which of the 3 wires? There's a pink, black/blue and blue/yellow one.
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Hablas espanol?

 

http://neomiata.com/garage/1999_Miat...20Diagrams.pdf

page 2. nothing goes directly to gnd. they are all interlocked.

 

I'm stumped. The directions on m.net say to connect AP5 to BP3, but there is no P3 if I'm looking at it correctly.
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True. But if you follow the diagram, the Pink is V+ for the a/c on LED and is hot key-on. When you push the a/c button, the pink and the black/blue are connected to blue/yellow. blue/yellow is a (shitty) ground.

 

According to the instructions on m.net the blue/yellow wire needs to go through a diode, should I still try grounding it?
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confusing at the least because there's two blu/yel and one goes to a 30A fan fuse!?

but yeah it looks like the Blu/yel out of the AC circuit goes to ground via the fan speed switch.

ben, do you call it shitty because it only goes directly to gnd in fan 1, otherwise it's thru a resistor?

 

That makes sense. No, don't touch the blu/ylw

Ground the blk/blu and the a/c comp should kick on. Ground the pink and the diode should light up.

 

Took me a minute to find what you're looking at. Yes, you are correct. There are (2) blue/yellow wires that provide power to relays. We're ignoring those. The blue/yellow wire we're looking at is between the a/c button and the fan switch. It's the ground for the a/c switch, run through the fan speed controller as an AND gate. For a/c to activate, the button must be depressed AND the fan speed controller must not be in the off position.

And phil, yes, you will need a diode on this blue/yellow.

 

****, I was wrong. If I'm reading the instructions right the diode is supposed to be on the blk/blue wire.
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The purpose of the diode is to prevent the blower motor from grounding through the a/c amp, so it wouldn't matter which wire you put it on.

 

So which wire should I ground?
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To test operation? Ground the black/blue.

BTW, I'm looking at the 99 schematic.

 

A refers to the plug on the car-side of the harness.
B refers to the NB pigtail.

A-P1 -- AC3 & B-P4 (fan speed 1)
A-P2 -- B-P5 (fan speed 2)
A-P3 -- AC1
A-P4 -- diode* (inline) to AC2
A-P5 -- B-P3 My problem is here, there is no P3 on the plug that goes to the HVAC

A-S1 -- B-S2 (fan speed 3)
A-S2 -- B-S3 (fan speed 4)
A-S3 -- B-S1 (ground)

L1 -- B-P1
L2 -- B-P2
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Even with the Diode on it? The dash and HVAC I have are from a 99.
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This is gibberish. Needs pictures.

 

1st pic is the NA pig tail, second two plug into the NB HVAC. The 3 wire plug is the a/c button.






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