A/C Unit Moanin' and Groanin'

[GrampS10Acious]

Hey to all,
I have been having problems with the A/C pancake compressor on my '92 2.8 L S-10 and was wondering if anyone has replaced theirs with an aftermarket unit like say a Sanden unit? I have put two pancakes on it and seem to end up with the same result, moaning at idle when the A/C is running. I have been all over it to make sure all mounting bolts are tight. I have remove the heatshield over the cat converter that made it sound like an aluminium pie pan was rattling around under there. Thought that if anyone has gone to a different type compressor this group would know...any Help???
Thanks,
Gramps

[spongebob]

if the compressors your buying are reman's,,thats your problem.
also flush the system next time, and pull a 500 micron vacuum.

[GrampS10Acious]

The first time I used a reman. and the second time I went brand new....still lookin' to go with an aftermarket brand

[spongebob]

try this site gramp's..
www.autoacforum.com

[Telkar]

Happens here too. Rebuilt A/C Comp. I prefer to drive with the windows down anyway, so I don't use my A/C much. I understand how annoying it is though. What I don't understand is my previous A/C comp was rebuilt as well, and didn't do it. Guess it was rebuilt to higher tolerances.

[GrampS10Acious]

Has anyone got any experience with any other after market A/C unit, like a Sanden 508
Gramps

[SSRob]

Not sure the compressors these guys use, or if they have any S-10 stuff, but they sure don't normally use R-4 pancake stuff!
They specialize in old old cars and street rods, etc.

Rob in AZ

[GrampS10Acious]

Gotta Link?

[SSRob]

Oopps!
http://www.vintageair.com/

Rob in AZ

[GrampS10Acious]

Thanks

[betterthanyou]

Its the nature of the beast. The Isuzu Rodeo had a damper attached to the compressor housing that was there to quiet the vibration. Once revved up they smooth out. If the FWD 3.1L vans of the era use the same compressor I bet they have the damper.

[jwvess00]

Hi there!

I'm with betterthanyou on this. I've had many R4-equipped cars, and just about all of them moaned. Heck, my '06 Solstice moans louder than any of them. I too have considered an aftermarket but not seriously.

One problem with using an aftermarket may be mounting it to your accessory drive. If you can work through that, and have custom hoses made (which shouldn't be too hard -- plenty of places can do that) you should be okay. Note that the R4's short stature is key -- there's not a lot of room around the compressor so a longer one may not fit in the original spot.

Also note that this A/C system is a cycling-clutch orifice tube system. I don't know if that matters when picking out an aftermarket compressor but it's something I'd mention to the vendor before purchase since it's not the only style in use on automobiles. Also note that in the original system the R4 compressor has no oil sump, and that the oil stays in the refrigerant (and to some extent in the receiver/dryer). If you change the compressor for an aftermarket, make sure to discuss this with the vendor to ensure the new compressor has an adequate oil supply without over-oiling the system.

[GrampS10Acious]

Thanks guys, ya know, I do remember that when this truck was new that the problem did not exist, it was only when the OEM gave up the ghost and a replacement was added but both replacements have. The darn thing transmits all the way through to the exhaust system! Oh well guess I'll try to quiet it as best I can by checking for all the places that could be touching somewhere and correcting.
Gramps

[betterthanyou]

Check the pulley size. GM used 2 sizes. A 5" and a 4.2". If your groaning is at or near idle then it is most likely because the compressor is spinning at a speed where its own piston is setting up a harmonic with the engine pistons. Changing the operating speed of the compressor with the correct pulley size will eliminate the harmonic by never letting the compressor get into that range.

[inkycu]

I had this problem and it appeared that it was the serpentine belt vibrating just after the alternator. After going through the recommended tensioner and belt replacement with no improvement, I began trying some other options and finally solved the problem.

The AC compressor has 2 bolt holes at the top @ 11 o-clock and 1-o-clock angle. I got some steel flat bar and made support brackets running from the alternator mounting bolt to the AC compressor by running a bolt through the empty ac compressor bolt hole. This alone eliminated most of the serpentine belt vibration. I also made a support bracket from the AC compressor to the power steering pump.

Since I put in headers, I replaced the 87 power steering bracket from the exhaust manifold with a bracket from a 86 2.8 s10. I used a bolt and a couple of nuts as spacers from the ps pump to connect it to the 86 bracket and no vibration.

hope this helps