Strange PSI's in AC system, no cold AC

[bohica2xo]

Feeler gauge between the clutch faces. .020 inch is good. .080 is way too big. (yes I have seen that gap)

Adjustment is made by removing the clutch plate. Behind it on the mounting surface there will be a few washers. These are the adjusting shims. You remove the same thickness you wish to reduce the gap by. So an .080 gap, you pull an .060 shim - and end up with a .020 gap. No need to replace a clutch.

Rattling noises can be several things. Idler bearings can get louder with load. The hub bearing on the compressor could be worn out. Isolating the noise can take a few tries. I recommend removing the belt, and rotating everything it contacts by hand, feeling for roughness or slop.

[Cusser]

The un-predictable compressor engagement is usually a clutch gap.

Just a year ago I had an intermittent AC issue on my 1998 Nissan Frontier, at about 255K miles. AC would just stop blowing cold, then after a few minutes would work. Since I have on this vehicle a dash indicator light I wired in parallel to the compressor wire, I knew that the AC clutch was getting positive voltage. So a couple of days later when the AC stopped blowing cold but the light was still on, I immediately pulled over and visually verified that the AC clutch was disengaged, even though it was getting power.

So I used a seized compressor from my 2004 Frontier to practice on, and figured out on that one that three 5mm bolts could be screwed into already-threaded holes to pull the clutch plate off. So I did this on my Frontier's compressor; I removed one thin shim, and put it back together, and it has worked fine since. I didn't need to unbolt the compressor or even remove or loosen the AC belt to do this.

[pippo]

Thanks, people for the spec on my Honda and the experience story you had!

Just got home and will try to get the "reading" of a feeler guage. I guess I will just jack up car a bit, crawl under, place a feeler between the clutch and comp. Let's see what I get..........

[pippo]

Well, people, the gap is 0.035. So, looks like the gap is not the culprit. I was hoping it was. Sheesh. Looking more like its time to get a new comp. Maybe not today, but soon. I am still getting cold ac, intermittently.

[pippo]

Ok, embarrasing as he**, I just started the car again, to check guages readings, and have a 3rd (4th??) look at things, and learned that rattling sound is not from

the ac compressor, but from the exhaust manifold shield!! It rattles againbst the manifold! It apparently is too close to it, somehow. Gonna wait til it coold, and bend it out a bit, then test again. But still, it blows ice cold air when car started, then take off for a drive , after 5 minutes, no more cold ac. High psi shows fluttering needle still.

[Cusser]

So when AC clutch disengages, is the AC clutch getting positive voltage or NOT?

If not, trace circuit to find out why not !!!

If so, carefully tap it with a wooden handle, be careful of moving stuff !

[bohica2xo]

Yeah Cusser, nobody wants to believe it is the clutch gap. Lots of compressors replaced for lack of an adjustment.

The hot resistance of the coil is greater than cold. Less magnetizing force hot. Add in some slightly higher resistance connections in the circuit... Quits working when it is hot.

Adjust the gap back down to .015 / .020 and it will work again.

Take a mirror & flashlight with you. When it craps out hot, leave it running, park & look under the car. Is the front plate spinning?

[pippo]

Thanks. Looks like I have some detective work to do. Much of this is new to me (chasing down voltage), so wish me luck.

[pippo]

Good to know, Al9! Some hope! Yes, Im hoping it is clutch related some how. Heck- even if I cant detect the problem like the pros here could do, Worst case I buy a new clutch kit (I asssume the come with new wiring harness/clips) and install! Not too $$$ of a fix, right?

[bohica2xo]

Or you could address the most common failure first.