ToySnakePMC

It’s been quite an absence of mine here on this fine forum. I currently have 2 other project cars in play this past year or so, but I want to finish up the AC to make my V8M a more complete package. It gets hot in the summer - as the hard top hasn’t been off in 5 yrs, lol..!

So, I have the Cadillac CTS-V compressor like many others around here, I would guess. My plans are to use a Vintage Air trinary switch to help control compressor and fan. That should allow me to completely avoid worrying about involving my E40 (correct name?) ECM from the ‘05 GTO as that ECM had a body control module (BCM) giving it such directions...

I hear that my compressor has an internal diode and can be quickly fried if I hook it up backwards. Does that sound correct?
My connector pigtail from GM is wired with WHITE wires so having never seen which wire would have originally been green (12v+?) and which one would be ground... I currently have a 50/50 chance of being correct. I’m just concerned since there could be difficulties if I get it wrong.

I’m no where near ready to try it as I’m just now formulating my plan. I have FM fittings for the compressor on the shelf, so I’m just now figuring out what it’s going to look like. Any help is appreciated.

thx. Patrick

ToySnakePMC

Lol, figured out my little problem when I looked at the compressor hanging onto the side of my engine as the plug connector has exposed wiring going to the clutch. One green & black stripe wire and a black wire. At this point, I assume black is ground/ negative. We shall see...!

Here’s a pic. You can check out my build thread around post #314 for the start of the AC installation that’s currently under way in the 9th month of 2020.

Handsoncarskt

I'll be at this stage soon, so your info is great. I'll be using a Vintage Air Trinary switch and condenser as well... what condenser did you use? and did you make Hybrid lines to the Miata box inside?

Thanks in advance
Kevin.

ToySnakePMC

Hello Kevin, I’ve got most of this AC installation on my build thread - starting near the bottom of page 13. https://www.v8miata.net/general-moto...na-794/page13/. The condenser and evap coils, and drier were from Rock Auto and are basic 1994 Miata components.

Trinary switch is the way to go, I believe. I have a current issue with my AC control wiring, lol! I figured it out Sunday evening, but left town the next morning so it will be next weekend when I dig into my dash and locate the correct red/green wire at (or near) the AC button I hope...

pecanflyboy

I have a 1999 with an LS3 crate engine and GMPP ECM. This GM ECM does not control the AC clutch or the AC condenser fan, but it does control the main cooling fan. Why do we need to rewire the existing Miata AC clutch relay and AC condenser relay? It seems like the Miata logic will work to activate the AC clutch and condenser fan when commanded on and needed?

Flyin' Miata instructions have me wiring the AC condenser fan to be triggered on with the main cooling fan. Then, they want to trigger the AC clutch with the "trigger wire" into the relay as opposed to just using the output from the relay? Is this just a lot of work to remove the three relays (main fan, AC condenser fan, and AC clutch relays), or is there a reason?

The builder of my car wired the main cooling fan into the GM Fan relay as described in the FM instructions. However, he kept the AC condenser fan and AC compressor clutch installed as they came from Miata. It works as advertised until the engine gets hot at idle.............

I'm getting uncommanded condenser fan and AC compressor relay activation from the Miata PCM when the main cooling fan is activated by the GM ECM fan relay? So, when at a stop light, the cooling fan, condenser fan, and AC clutch come on until the engine cools and the main cooling fan is deactivated. I've narrowed it down to the ground trigger from the PCM. Any ideas?