A/C Compresson Cummins C

RichM · Jun 14, 2003

This problem started on my Cummins late last year,then the winter came and I did nothing about it,now the hot weather is here and the problem still exists.
When I have the A/C on at about 1500 to 1700 RPM the A/C compressor makes a groaning noise and seems to suck power out of the engine. I noticed that the belt is quite tight,and have replaced it in the past.
In the past you never noticed if the AC was on or not but now you can tell as the engine is sluggish with the A/C on.It starts to happen when the engine warms up,at low rpm!s sometimes you hear it,when you turn it on at idle it does not drop the engine speed. It puts out good cold air though,has 685,000 on it.Hate to buy a new compressor at this stage so any advice would be appreciated.

Refer Hauler · Jun 14, 2003

I had a very similiar problem and it was the belt tension adjustment bolt that was broke in half. I quess the A/C clutch engaging caused the unit to vibrate on the tension bolt. Found this when pulling compressor off to replace even though like yours it blew cold, I thought the bearings were gone

RichM · Jun 14, 2003

Thanks a lot.I think I have replaced the tensioner b4,But I bet thats what it is. I will check on Monday.

Weave · Jun 17, 2003

Just a couple of questions. Have you been continuously replenishing the system with refrigerant? If so, it sounds like the system is overcharged. If not, what color is the little eye on the receiver/dryer? If it is white, the dryer is no good, and the system is filled with moisture. This moisture will enter the compressor as a liquid, and liquids cannot be compressed, so it really bogs down the compressor (and will ruin everything else if let go too long.)
I would replace the compressor and receiver/dryer. They really aren't too expensive. The comp is about $150 and the dryer $30. The system will have to be evacuated after replacement, then recharged with refrigerant and oil. The whole job should be less than $350, which beats dying from heat stroke.
I just went through this scenario with my truck, and got to do the work myself with supervision. I found getting the right amount of refrigerant in the system a little tricky- I initially WAY overcharged it, but luckily the compressor has a pressure relief valve, that I witnessed pop big time! I was scolded for not charging the system at a high enough engine rpm. :'(
But... it's working great now, an icebox the way I like it!
-Weave-

RichM · Jun 18, 2003

I checked the view port on the dryer,it shows blue which I think is OK. I noticed when the engine is running at about 1500 the belt is bouncing around,might be slipping under load.When the engine is off the belt is fairly tight though. Also found one of the inside bolts that hold the compressor to the block is missing.Looks like you would have to remove the valve cover to get to it.Wonder when that happened??.

Weave · Jun 20, 2003

A case of the Cummins A/C compressor mount blues. Guess you just have to dig in there and get all the bolts replaced. The pivot bolt has to really (REALLY) be tightened down to keep the thing from moving under load. I used to hate that as I could beef it down at home with the tools I have there, but could not loosen it to replace a belt in the field with truck tools. Even with everything done right on that V-Belt design, the belt will still flap around a little while the compressor is running.
Your dryer is OK with blue in the sight glass. Still, once you get the mount issue resolved, have someone hook up the gauge manifold to make sure the pressures ore OK.
-Weave-

RobZip · Jun 20, 2003

>The pivot bolt has to really (REALLY) be tightened down to
>keep the thing from moving under load. I used to hate that
>as I could beef it down at home with the tools I have there,
>but could not loosen it to replace a belt in the field with
>truck tools.

Try some red #271 LocTite. Remove and clean the bolt, oned drop on the threads and guaranteed it won't shake loose again. Of course the directions say you need to apply heat to soften the LocTite before removal but I only find that to be required on smaller bolts. Use the stuff sparingly - it does a fine job.

When I lived in Jacksonville I used this stuff to assemble my radio control race boat engines. Never had problems with those little 2 cycle screamers coming apart. The local auto parts stores started keeping the stuff behind the counter though. Too many guys were using it on small block Chevy valve cover bolts, then raising hell when they twisted the bolts off at valve adjustment time.

One of my little screamers below.

Weave · Jun 20, 2003

"My toy is better than your toy!" "Oh no it's not!"... "MOM!!:7
I have been building RC vehicles for years to take my mind off work and other things;-) , along with restoring cars and motorcycles. This is a Traxxas T-Maxx 4x4 with all the plastic parts replaced with aluminum. It has a solid steel roll cage, a 1 HP engine, and a computerized radio system.
-Weave-
I know this is off the subject, but the posts have been a little slow as work has picked up for many.

RobZip · Jun 21, 2003

RE: Toys!!!

I used to do a few RC cars in the winter to stay sharp on the sticks during off season. There were several indoor racing venues for electrics and a few gasser off road type tracks too. Thats a nice Traxxas rig ya got there.

The boat above was a Class C outrigger - .21 OPS power, the only small hydro I ever raced. I just did that one to be a pain in the arse to a fellow club racer who had that class locked up pretty well for a few years.

My favorite 'riggers were Class D boats - OPS .45's seriously ported and tweaked up. Always tore 'em down and put heavier sealed crank bearings in, RPM titanium con rod, small chamber head buttons and much pipe magic. The D boat would run in the mid 70 mph range on 50% nitro.

My all time favorite was a Class F Mongoose hull - twin OPS .90's. The twin was a real brute - 114mph and darned expensive to run. Each run would burn a quart of fuel and fry at least one plug. The inside motor pulled hardest so that plug got switched to the outside on the next run and would usually blow at the end of the run.

At $32 a gallon for fuel and close to $5 each for the OPS gold plugs, a full tank run cost around $13 each time it went out providing there was no other damage - roached pistons, collisions with turtles, etc.

There's nothing that compares to lighting up a big twin singing away through exhaust throttles and unmuffled pipes at 7 am on a Saturday morning. Talk about adrenalin! Sure makes the ducks sit up and take notice.

Weave · Jun 21, 2003

RE: Toys!!!

The T-Maxx is my winter entertainment too- very fun in the snow, and I get loads of it here in Buffalo. Costs about $6.00 an hour to run on 15% nitro with .16 engine. Haven't tried the boats yet, but I only live about a mile from Lake Erie and probably should, but the thing is I don't want to swim to fish it out of the lake if the engine dies. I'll just stick with land vehicles for the time being

-Weave-

RobZip · Jun 21, 2003

RE: Toys!!!

>but the thing is I don't want to
>swim to fish it out of the lake if the engine dies. I'll
>just stick with land vehicles for the time being

There's ways to deal with that. A fetch dog works well. At smaller lakes a retrieve pole - a short casting rod, 10-15lb test line and a large rubber ball to throw out over the stranded boat works. Most larger clubs have a retrieve boat, a small jon boat with outboard, or you can keep a wide hull stable electric craft with a net fitted boom draped over the sides. Simply come alongside, snag it and power back in.

Some of those early days of engine tuning will get ya on target real fast after ya flame out in the lake several times in a row. The engines have to be set up slobbering, crackling rich to run right under load. My twins blow dropplets of lube out the pipes about the size of a ball point pen dot.