348 air conditioner wire, does anyone know what this is?

Hi Brian. Please see attached 348 A/C Diagram & a pic of the power wire to my compressor while I was doing the major. At the bottom of the drawing, you can see number 98. That's the A/C compressor clutch. It shows that there's one wire (I'm sure 12V power) and then a chassis ground. So I'm sure the intent is that when the compressor is bolted to the support bracket, that the compressor clutch is grounded through the bracket to complete the clutch circuit.

I didn't have a separate ground wire on mine, which has the Nippondenso compressor. It looks like someone decided to run a separate wire to ground your compressor, perhaps to make sure the compressor/clutch was grounded. Or perhaps it's possible that someone modified or installed a different clutch on your compressor and used that grounding method. Not sure. Do you have a different compressor than the Nippondenso?

I don't believe the wire is factory, and that either the early or late cars would have that. I suppose you could leave it disconnected and see if your compressor still works, and remove it if it does. Hope this helps... you can PM me if you need other help.
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That may be a pullup resistor or clamping resistor (zenor diodes, really) used to insure a precise voltage.

It's a hack job, though.

 

Got your PM... Sorry Brian.. I wanted to post here again because I see I misunderstood your first post. It's very hard to see the wiring on my car with everything installed, but see my attached pic. I also had some wiring that I think went inside the compressor and bolted to the compressor case. I was assuming that was just a ground wire from the clutch inside the compressor.... I only cleaned my unit up; didn't have to work on it at all, so can't really recall for sure.

It sounds like you're saying you have a wire spliced into your power wire and is grounded to the compressor case through a resistor. That makes no sense... that can't be stock. From your PM, it seems your problem is that you are blowing the compressor fuse each time you turn the A/C on. And that you also have removed this spliced wire and resistor, and after 15sec your fuse still blows. It sounds to me like your clutch is bad and/or shorted, or other wiring is shorted somewhere. I"m still not sure why someone added the wire and resistor.

The data with the drawing mentions that the clutch has 3.0-3.5 ohms resistance (apparently). I'd measure resistance on your clutch from the compressor connector to the compressor case, and see what you get. I'll bet it's way off or shorted (near zero).

Also, check resistance between the main power plug (as in my first pic above) and ground, to make sure you don't have a short in your main power wiring (should see near infinite resistance). That way you can be sure the problem is in your compressor/clutch and not in your main wiring. I suspect you'll have to get your compressor repaired or replaced, but let us know what you find.
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Seems like there may be an intermittent short in the wire inside the clutch area. Or could still be some short in the clutch. I'm not sure what it takes to disassemble the compressor to get to the clutch, but you could search for 348 compressor threads to see what you can find. Also could be something in the 348 Parts Interchange thread here:

http://www.ferrarichat.com/forum/showthread.php?t=50339

I doubt you'd be able to repair it in place, even if it's a simple fix, so you may have to get the system evacuated and then remove it. Steve at the C&C suggested I use The Mustang Shop in Chandler to get my system evacuated for my major, and they also recharged it afterwards. They did a good enough job. Or you could post a thread in the Arizona forum to see if someone can suggest another shop to have the system evacuated and compressor and clutch checked or repaired.

Turbo & Electric in Phoenix repairs turbos and alternators, and they may be a source for compressor repair also (not sure). I picked up my alternator regulator and rectifier there. Of course, some will also suggest Andy Falbo or Alex Traverso who work on a lot of the Ferraris here in town. Let us know what you find as you progress!

 

Looking at the original post, I think I could understand it if what looks like a resistor was actually a capacitor, to reduce or eliminate the voltage spike when turning off the compressor

 

Hang On,

That is factory wiring for the Sanden OEM A/C Compressor. That little 'resistor' is not a resistor. It is a Zener Diode and is swaged on the the ground wire that has a screw tab that goes right on the compressor body. It is there to prevent milliamperage current from flowing backwards into the open circuit wire that supplies voltage to the coil in the clutch. When there is no voltage being supplied (coil is not energized and A?C compressor is not engaged) the coil still spins and that geenrates a little amperaage that can flow through ground. The Zener diode stops that and potentially sending back amerage to the control unit.

Don't snip this or by-pass it.

 

Welcome to Fchat, and great first post! I saw Brian at an event a couple weeks ago, and he had talked with a local Ferrari expert, I believe Alex Traverso, and Alex basically said the same thing! I don't recall what the solution was to Brian's blown fuses, but I think it just may have been that the Zener diode was bad. Brian.. any update on your A/C?