Nippondenso A/C clutch

[Driven97]

Ok, so a new compressor had my A/C blowing nice and cool - for a little while. Troubleshooting today and I noticed the clutch wasn't engaging. I am seeing 12v across the terminals with the AC on, 0V off.



I take it I somehow fried the clutch coil, as it looks terrible. Looks like it's still available - p/n 93012690700 but any idea as to why or what happened? This is the original clutch assembly as my reman compressor didn't come with one.

[Driven97]

Since I'm pretty sure I solved this:

I had a bad ground between the compressor and the chassis. The bolts for the compressor weren't tight. I tightened them up and got a much more solid 14.0V on the clutch circuit.

Low voltage = slipping AC clutch = heat = self destruction.

Now I just need a new clutch...

[kuehl]

Remove the front clutch hub (12 or 13 mm nut, use air gun), be careful not to lose the "air gap" shim washer(s) that will either be on the shaft or stuck in the hub's bore. And don't loose the shaft key.

Remove the pulley; using snap ring pliers and watch your eyes when you do it, they can fly off.

Remove phillips head screw holding down clutch wire to comp body.

Remove coil; using snap ring pliers and watch your eyes when you do it, ditto.

Test the coil resistance, should be 3 to 3.5 ohms.
Inspect the epoxy encapsulating the coil windings; if cracked it overheated.
If coil is shot find a good used one.

Reassemble and insure you have .015"-.030" air gap measured at 3 places (120 degrees apart) around the clutch, between the pulley and clutch hub.


Porsche AC

[Driven97]

Is the "air gap" shim a tuning item then I take it? When I swapped compressors I just put the same one back on, didn't measure the gap. I'm assuming too much gap could also cause slippage / meltdown.

Thanks, BTW.

[kuehl]

Air-gap is a mechanical clearance term ( valve clearance, spark plug gap clearance, driving under a bridge clearance, safe distance between you and the 'x' clearance).

If you do not have enough gap (space) between the hub and pulley then either
it will grip and pump all the time or it will drag (wear and overheat).

If you have too much gap the magnet won't be able to pull the hub in and
your pump won't pump or it could drag.

Compressors that come with a clutch assembly should have the gap set, but like
new spark plugs out of the box... check it; compressors are heavy (mass), 16 lbs., and sometimes things get damaged in transit and the hub or pulley gets bent.

[Driven97]

My compressor came "bare." Looks like the body of the compressor dictates the position of the pulley, where the shaft dictates the position of the drive hub.

Ugh, now I have 1 more thing to check when I get a replacement. And of course I don't own feeler gauges, so I get to buy more tools...

[kuehl]

The aluminum front nose hub section (body) of the compressor has a pin that aligns with the coil; coil wire should be at right side looking at your bumper. The rest: pulley and front hub does not have an orientation because they spin; other than the key way on the front hub that slides over the key on the shaft.

PP Article on Nippon Comp Rebuild



" And of course I don't own feeler gauges, so I get to buy more tools..." Omg! Omg!
Look. If you want to own a Porsche you got 2 choices:
A) Pay someone to fix it.
B) Buy the tools and have fun like the rest of the community.
There are other choices but I'm being nice today and sharing my toys.

[T77911S]

i just put a new coil on my jeep. it came with the spacers to set the air gap. it had 2 ways of doing it. one was to measure it and shim it, the other i thought was better. basically keep adding shims until the clutch plate does not hit the coil. this made the most sense since i had no spacer that would get it any closer. it works fine.
the coil was about $100. everyone said jsut replace the compressor.

BTW, this is the second jeep i have had that the coil for the AC made it run bad. the coil and ac still worked, i just think it was pulling too much current.

[kuehl]

Here ya go,

Clutch Assy for Sale on PP Classifieds