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Topic: AC Compressor Clutch Bearing (Read 947 times) previous topic - next topic

AC Compressor Clutch Bearing

When I was installing a new alternator fan belt, I noticed that the ac compressor pulley had some play and did not turn easily.  The compressor belt has to come off first before the alternator belt can be removed.  A puller is required to remove the clutch and an auto parts store had a loaner kit for that.  Some snap rings have to be removed as well.  After removal found that the bearing was mainly locked and some wear had occurred on the neck of the end plate that holds the bearing. The wear is just on the area opposite the drive pulley.  Initially thought I would have to replace the compressor, but now have decided to try to build the worn area back up using brass shim and JB weld.  Not sure if this will work, but will give it a try.  $25 vs $400-500 or more for compressor replacement which would include filter/dryer, and refrigerant.  The wear seems to be less than 1/32", but the pulley did contact the field coil.  The bearing is a press fit in the pulley, and at least a close fit on the end plate of the compressor.  Hope it works, may take a few days.  Additional use would certainly have ruined the compressor.  Others may want to check for wear on this part, the pulley should not have any play and turn freely with the belt off. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: AC Compressor Clutch Bearing

Reply #1 –
I do love the idea and it is possible for a temporary fix, but I also feel it will cause you a big problem at the worst  time possible, like when you are nowhere near home where you could have it repaired with a reasonable amount of money. Being broke down away from home is a most unpleasant experience, not to mention very expensive.
I do not know the setup on a 270 coach, but what damage could be caused by it all going wrong ?
Just an opinion from the village idiot ;D

Re: AC Compressor Clutch Bearing

Reply #2 –
Quote from: Dave M –
I do not know the setup on a 270 coach, but what damage could be caused by it all going wrong ?
Hopefully not  much, it is driven by it's own belt that doesn't drive anything else.  Just remove the belt and keep on driving without dash air. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: AC Compressor Clutch Bearing

Reply #3 –
I did succeed in getting the AC compressor clutch back in operation.  One of the harder parts was locating the correct bearing.  O'Reilly ordered one that was the wrong size, offered to order the correct one for $85, which I declined.  Bearing shop didn't have one and their distribution center didn't have it.  A local auto AC compressor re-builder had one for $33. 

All the wear on the end plate neck was on the side opposite the drive pulley and at the most worn spot amounted to 1/64".  Doesn't sound like much but it caused quite a bit of wobble in the pulley side to side.  Also with tension on the belt it was no longer concentric with the compressor shaft.  I had some .004 brass shim that I cut a strip of, the same width as the bearing.  From that cut 4 pieces of different lengths.  The longest piece was 1/2 the circumference of the end plate neck and the shortest piece about 1/16 the circumference.  Shortest piece applied 1st with a little JB weld and then the longer pieces.  Wrapped the whole thing with waxed string to hold it in place until the JB weld hardened.  Most of the JB weld was squeezed out by the string.  I had an oversize o-ring in the snap ring groove to keep out the JB weld.  Next day found it was too big to get the bearing on.  Used a file and a piece of emery cloth to reduce the size.  File, sand, measure, and try the bearing.  Eventually removed the top layer doing that.  Then it was too small.  Applied a piece of .001 shim and it was too big again.  A little sanding with the emery cloth, much measuring with a caliper and I got it to the point where I could get the bearing on with a mallet, and get it off with a couple of pry bars.  Replaced the field coil and reassembled the clutch.  The bearing is a press fit in the pulley, installed using a vise and the old bearing. 

It now works like it should, but found the clutch cycling on and off.  Added some 134a refrigerant which reduced the cycling, but both the high side and low side pressures are too low.  Most likely the thermostatic expansion valve is not working properly or it's clogged with desiccant from the receiver-dryer.  Looks like I will be going to an AC shop anyway. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: AC Compressor Clutch Bearing

Reply #4 –
Jerry,
You do some amazing stuff.  Sorry to hear that after all the compressor work, the unit is still not 100%.  I had the same issues with cycling on/off of the compressor.  It turned out that the expansion valve and drier had to be replaced due to contamination (very likely the "cr*p" work done at Cummins in previous years).  There's a bit of work to get the expansion valve out, but once you remove the front part and top lid of the doghouse, it's doable.  My a/c repair shop asked me to do the removal so as not to charge me for it.  It took me less than 15 minutes to do the removal and about 30 minutes to put it back together.
 
Here are some pictures:
 
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: AC Compressor Clutch Bearing

Reply #5 –
Forgot.  If you go to my profile, there are other pictures related to this topic.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: AC Compressor Clutch Bearing

Reply #6 –
Peter,

I knew your expansion valve was replaced from previous posts and I can see how to get to it.  Don't be too eager to blame Cummins.  From what I have read, it is not too uncommon on older units like ours for the desiccant in the dryer to get into the valve as it deteriorates with age.  There is supposed to be a screen in the valve inlet to catch it, but enough of it will block the screen reducing the amount of refrigerant going into the evaporator resulting in poor cooling.  The desiccant in the screen is supposed to be similar to sand.  Did you remove the valve or did you just remove part of the dash?  Was the receiver-dryer also replaced?  It is located on my coach in the area behind the left rear wheels up high.  It is standard practice in most cases to replace the receiver-dryer when the system is opened to replace a part.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: AC Compressor Clutch Bearing

Reply #7 –
Jerry,
The receiver-drier was replaced this time as well as when I purchased the coach in 2003 along with the compressor, the condenser coil was refurbished as well.  But the system kept on with a slow leak of refrigerant all these years.  I hope this time the system is fixed.  I'm told a need to run the dash A/C at least once a month.  This is really going to challenge me as I'm not used to starting the coach during its winter hybernation.  ;D
 
I only took the dog house apart and reassembled it.  The A/C techs took care of the rest.  And the location for the drier is the same as your coach.  BTW, my system takes 5 to 5.5 lbs R134a.  It's a 34 foot coach so donno if this capacity varies with the length of the hoses in the longer coaches.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH
 

Re: AC Compressor Clutch Bearing

Reply #8 –
Peter,

Thanks for the info on the quantity of refrigerant and a longer coach will require more.  I overlooked running the AC once a month this winter, maybe a good thing since the bearing was frozen.  Running the AC circulates the oil and lubes the shaft seal which will  leak if it dries out.  The refrigerant also migrates through the rubber hose with time just like air migrates through the rubber in a tire.  With most refrigeration and home air conditioning the piping is all metal and the compressor and electric motor is in a sealed case, so there are no leaks and it can last for years.  Cars use a combination of metal tubing and rubber hose.  I'm not sure what FT used between the front and rear of the coach, maybe someone knows and will reply.  Less hose equals less loss of refrigerant, but vibration will fatigue crack metal tubing.  If I'm wrong about any of this, I hope someone will speak up. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt