AC wiring experts

[93blackbeauty]

Just went to a plug and play Megasquirt based PCM. Wanting to get AC working again and im seeing 2 pins 10 for pressure switch input and one 43 ac panel input. Does the PCM control any of the AC functions or is this a reference for idle control?

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[Raymond_B]

Just went to a plug and play Megasquirt based PCM. Wanting to get AC working again and im seeing 2 pins 10 for pressure switch input and one 43 ac panel input. Does the PCM control any of the AC functions or is this a reference for idle control?

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PCM has no function in AC other than idle up as you said. If you're going to use electric fans I can share my circuit diagram for my Megasquirt that has fan control and ac control along with WOT cut out etc.

 

[93blackbeauty]

PCM has no function in AC other than idle up as you said. If you're going to use electric fans I can share my circuit diagram for my Megasquirt that has fan control and ac control along with WOT cut out etc.

I plan to us electric fans eventually and that would be awesome.

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[Raymond_B]

I plan to us electric fans eventually and that would be awesome.

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Cool, OK now this uses some MS3X pins, but it will give high and low speed control, AC idle up, WOT cut out etc.

******Warning******* My truck isn't running yet so I have not tested it. If you let the magic smoke out or burn something up it's not my fault

 

[93blackbeauty]

Cool, OK now this uses some MS3X pins, but it will give high and low speed control, AC idle up, WOT cut out etc.

******Warning******* My truck isn't running yet so I have not tested it. If you let the magic smoke out or burn something up it's not my fault

That's perfect and that should work just different pins. Im using stinger performances PNP unit. It has several pin options for fan control I can jumper it to a handful of different places but the other diagram is helpful to setup everything.

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[svtlightning207]

Not sure about your ecu- set ups- do they have built in protection on outputs? I'd look into installing flyback diode, or MOV to protect the ecu- check the documentation that came with it to verify- I'm assuming you've looked into it, and it probably has built in protection- but just a thought. The collapsing magnetic field when an inductive circuit opens induces back into the circuit, usually several hundred volts, which in turn fries transistors. Most modern cars now are all computerized and typically have warnings about installing relays into circuits. Id recommend a separate fused feed from your 12v constant to relay 1 & 3- if one circuit fails and pops a fuse, you will have the other to fall back on.

 

[Raymond_B]

Not sure about your ecu- set ups- do they have built in protection on outputs? I'd look into installing flyback diode, or MOV to protect the ecu- check the documentation that came with it to verify- I'm assuming you've looked into it, and it probably has built in protection- but just a thought. The collapsing magnetic field when an inductive circuit opens induces back into the circuit, usually several hundred volts, which in turn fries transistors. Most modern cars now are all computerized and typically have warnings about installing relays into circuits. Id recommend a separate fused feed from your 12v constant to relay 1 & 3- if one circuit fails and pops a fuse, you will have the other to fall back on.

Excellent input, thank you!

 

[svtlightning207]

I'm a bit confused by your set up?? why the need to have fan 2 running before fan 1 can come on? I don't know much about e-fan set ups other than how to wire them.. I run my fan on low speed only. I'm mostly curious on how people trigger their 2 speed or 2 fan set ups.

 

[93blackbeauty]

I'm a bit confused by your set up?? why the need to have fan 2 running before fan 1 can come on? I don't know much about e-fan set ups other than how to wire them.. I run my fan on low speed only. I'm mostly curious on how people trigger their 2 speed or 2 fan set ups.

I haven't done an L before but I always used thermostatic switches. Temp 1 limit fan 1 activates temp 2 fan 2 activates and then kicks off like 10 degrees below on temp.

But we also have Megasquirt PCMs which have built in fan control which I've never done mine have always been thermostatic stand alone controllers.

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