AC Clutch getting RED hot???

Did a bunch of work to my car over the past couple of weeks.  Replaced valve seals, new water pump, re-install headers, etc.  Started it tonight for the first time in a couple of weeks and the AC clutch got so hot the pins were bright red.  And it had only run for a minute or two. Now the compressor has been leaking over the past few months, so I was expecting to have to replace it, but I have never seen one get red hot like that.  

Is it just out of oil?

Back onto the lift!!

Bad Clutch Bearings (see it quite often on the big trucks) Time for a new Compressor/Clutch.

So I Will redo the system. What should I replace? Dryer, compressor, anything else?

Compressor or just the clutch, accumulator, orifice tube.

I will do the whole compressor. I figure 270,000 miles it might be time.

There is no dryer per se on the CCOT system in the B-bodies. The part you are thinking of is the accumulator. I would also change the orifice tube -- it has a screen that (hopefully) has been capturing any debris thrown by the compressor, so the screen may well be plugged by now. Don't forget to drain and measure the oil inside the compressor and accumulator, replacing it with at least the same amount.

All this assumes there was no sealant added to the system at some time in it's past life. Most sealants are moisture-reactive so opening the system may activate the sealant inside the system, causing problems.

In addition to a new accumulator, compressor warranties require flushing (with a flush machine and approved chemicals -- not one of those pressurized spray cans!), all new components or an inlet filter. I suggest the inlet filter. There are some that are cut into the line but my favorite is a screen that presses into the compressor inlet line. GM markets a kit with a variety of diameter screens.

I have yet to find a definitive list of what vehicles require which screen size. I do know that a 1995 Roadmaster takes size “A” – 0.510” diameter, to fit lines from .499” to .507” ID. GM Part # J44551-10, AC Delco part # 15-21186. All B-bodies from 94 to 96 use the same compressor so I suspect they use the same screen. The kit comes with a special tool to press the screen into place, but it's a POS tool and a bit of ingenuity will suffice.

Pull a vacuum for at least 1/2 an hour before filling, just to get any air and moisture that entered when you opened things up out of the system. That's assuming you install the new parts right away. If it's open for more than a few hours, try to hold the vacuum overnight.

Since it's a 94, replace the dang belt while you are in there. It's a PITA to get at, so you may as well put a new one on while you're there.

Read my article on this forum on the fastest way to remove the LT1 AC compressor. Slot the bracket before you reinstall everything. You're welcome.

What's a "dang belt"? Was that a '94-only part? Does that go inside the compressor, or on the clutch somewhere?

The drive belt that runs the compressor. Changing a belt should be a 2 minute job, not require unbolting things like the radiator pipe.

compressor is seized,. clutch is engaging,.

buickwagon wrote:

There are some that are cut into the line but my favorite is a screen that presses into the compressor inlet line. GM markets a kit with a variety of diameter screens.

The kit comes with a special tool to press the screen into place, but it's a POS tool and a bit of ingenuity will suffice.

All good professional advice,.but a little intense,.

whats the purpose of the orfice tube then?

So Autozone has a set of manifolds, a vacuum pump, "professional" flush kit (consists of a reservoir, air input hose, and blower hose) in their Loan-A-Tool program. AdvanceAuto had a 20% coupon this morning for online orders so I got a compressor, dryer/accumulator thingy, replacement tube wha-cha-ma-call-it, and some 134a. I will begin remove the compressor today so I can see if I have to take a header back off. The loan a tool parts will be to AZ tomorrow after church. Maybe I can get it all done tomorrow.

Flush it all, mount it all up, and vacuum it down for 45+ minutes. Some fresh juice & oil, and we should be good to go.   

WOW, I'll join the club. Just went out to the driveway to top up the AC in MacWoody's wagon before it goes to the left coast, and figured I'd check the pressure in the SS while I was at it. Started the car, put it on MAX, and it was blowing cool, with the compressor cycling. Not bad. In the amount of time to walk 50 yards to my tool box, I heard metal squealing noises, and came back to the car to find smoke coming out of the three holes on the clutch. Damn.

Oh no it's contagious!!!

[quote="phantom 309"]

buickwagon wrote:

All good professional advice,.but a little intense,.

whats the purpose of the orfice tube then?

Actually, I'm not a professional. I'm a shadetree mechanic just like most of you. However, AC service is a little intense and most shadetree mechanics don't seem to fully understand it -- certainly not as well as the motor or suspension, etc. Neither did I at first. I learned most of it the hard way. That's why I wrote an AC primer: for others to learn the easy way and avoid some of my more expensive mistakes. You can find it here: http://buickforums.com/forums/threads/26737-Basic-principles-of-Auto-AC.

It describes the function of the orifice tube too, but in short, the orifice tube is a small hole that separates the high pressure side from the low pressure side. It includes a screen to prevent debris from clogging the orifice. It hides inside the line from the condenser to the evaporator, in the connection at the condenser.

BTW: I have a recovery system, vacuum pump, manifold, sealant detector, leak detector, black light, the complete Delco filter kit, a kit of AC o-rings, bottles of oil, Schraeder valve kit, clutch tools, 30lb cylinder of R-134a, etc. etc. I have used and use all of the above servicing my family's AC systems. If a member of this forum is in the Muskoka area, I would be happy to help you with your AC problems

buickwagon wrote:

Actually, I'm not a professional. I'm a shadetree mechanic  

BTW: I have a recovery system, vacuum pump, manifold, sealant detector, leak detector, black light, the complete Delco filter kit, a kit of AC o-rings, bottles of oil, Schraeder valve kit, clutch tools, 30lb cylinder of R-134a, etc. etc. I have used and use all of the above servicing my family's AC systems. If a member of this forum is in the Muskoka area, I would be happy to help you with your AC problems

That would be awesome,. i can't get the orange cars' a/c to work.

coming to Hershey/Carlisle anytime soon? jk

BigBlackBeaSSt wrote:

coming to Hershey/Carlisle anytime soon?

Sorry, I haven't been across the border much since 9/11. I like America. I like Americans. But your government scares me, and your constitution protects citizens, not people.

(Note: this is not an invitation for political debate, just an explanation of why I won't be trying to cross the border with a wagon load of AC tools any time soon.)

Don't worry, our government scares me to!! I am sure they would not have a sense of humor about a bottle of refrigerant.

You should see the look on the TSA agents faces when I fly with PCMs in my carry on bag!

Got it apart.  The orifice tube is ridiculous.  I think I could do ok it I recycled all the aluminum on the screen (pics to come). It did not take very long to get it apart.  I flushed the condenser first with air than the flush kit I borrowed from AZ.  Worked great.  

Removed the motor mount bolt and jacked up the motor on one side to get the compressor off.  Will slot the bracket before I re-install.  

Taking a break (back issues).  More to come later.

Make sure you get all the flush out. 15 minutes of flushing = 45 minutes of blowing out flush residue.

Cleaned it up and blew out all the lines until dry. Replaced all the o-rings.

The fluid would not flow through the evap. I put the flush into the accumulator side of the hose and only air blew out of the other end. Blew back the other way and the fluid came out. Is this a concern?

OIL? The pump came with 6.8 oz in it. I lost just a smidge (.5 oz maybe) when I changed it from a bolt to the original stud from the factory compressor (someone commented that it would be easier and I agree). The accumulator is new and the evaporator and condenser are empty of course. So the service manual says 1 oz for the condenser, 3 oz for the evaporator and 3.5 for the accumulator. So do I add more?

The old compressor and accumulator had nothing in them, it had been leaking for months.

Put a quick vacuum on it and it holds well.

It is recommended that you dump the oil the compressor shipped with and replace with new, just in case the oil picked up some moisture while sitting on a shelf.

(That said, most compressors come with blanking plugs, so I'm not sure how the moisture is supposed to get in there. And I would think the compressor manufacturer would use an appropriate oil.)

Whatever you choose it would be a good idea to crank the compressor over by hand a few times before spinning it with the engine, just to get the oil distributed a bit, and pour the balance of your fill into the accumulator. The required oil fill for your model year should be on the underhood sticker.

factory service manual says that the capacity for the compressor is 6 ounces, 1 oz for the condenser, 3 oz for the evap, and 3.5 for the accumulator. I added 5 oz of additional oil to the 6.3 ish still in the compressor. That should be good.

Put one of those screens in the system as per your write up and a suggestion via the phone from Joel.

Thanks guys. Under vacuum as we speak. Holding 26-27 psi.

Yes, by all means, turn the compressor over by hand to pump out all of the oil BEFORE you try to engage it with the engine running. It'll be extremely hard on the equipment if you don't.

Turned it over by hand several (30-40) times and gave it a full 134a charge. Works great! Lets hope I have no leaks. I struggled to get the screen in fully so it took me FOREVER but now I know. The stud also kept backing out of the compressor. Next time no anti-seez but lock tight instead. Live and learn.

Thanks for all the help.

BigBlackBeaSSt wrote:

Turned it over by hand several (30-40) times and gave it a full 134a charge.  Works great!  Lets hope I have no leaks.  I struggled to get the screen in fully so it took me FOREVER but now I know.  The stud also kept backing out of the compressor.  Next time no anti-seez but lock tight instead.  Live and learn.

Congratulations on a job well done. Enjoy.

(Oh, and the special tool doesn't really make putting that screen in a lot easier.)

yeah it would have been much easier if I thought about it ahead of time and put it in when the compressor was out

cool!

Now come over and fix mine!

So I "cheated" yesterday.  I was not sure I had enough oil and/or to much refrigerant in the system.  It is really hard to know when to stop and to get answers as to exactly how much oil.

I was in Philly and a friend of a friend (mtrhead79) has a gaarage and does work very reasonably.  I called and Todd had a few minutes to check out the Not Rod.  So we put it on his machine, drew it down, added some oil (should have 12+/- 1 oz in it now, and put the proper 1.75 lbs of 134a in her.  Piece of mind for a few bucks.  

Note to anyone doing this:  Next time I would do the job less the coolant and/or oil and have a shop fill it for me.  Less money and more confidence in the long run.  It is ice cold now, better than I had it.

In summary and to do it again:

Remove old compressor, orifice tube, and accumulator.
Flush system with the AZ loan a tool flush system (done be shy here!).
Blow out the system with compressed air.
Install inline screen in suction side of compressor hose ($10 at AZ and in stock)
Install compressor and accumulator.
Make sure there is sufficient oil in the system. I think (someone check me) this should be about 13 oz.
Take it someone you trust.
Let them vacuum it down and refill the refrigerant.
Drive it til it breaks again (hopefully another 270k miles)

Absolutely nothing to do with the subject at hand but every time I enter this thread with either my Ipad or Android phone I get redirected to a screen trying to sell me an app or game. It's only this thread. Anybody else get this?

I get that all the time when on this forum via mobile.

It is also worth noting that the warranty fine print demands proof that you replaced the accumulator/dryer and had the system professionally pumped down and recharged.