York AC Compressor Experiencing Variable Load

Dave Clifton

Dave Clifton

New member
What I thought was a grenading york turned out to be the fan belt slapping the fan. So I tightened the belt and started close observation. Never noticed before but the load varies on the compressor during a clutch-engaged run.

When the load builds, the belt on the pulley top side really flaps. Then for some reason the load dissipates for a while and the belt settles down. Before you ask, yes the clutch is engaged at those times. My other cars seem to present a constant and steady load. The load appears to get greater as the engine compartment warms and the compressor run-time lengthens. I also notice the efi feeling the load and it injects a bit more fuel to keep the rpms at programmed idle speeds. So there is definitely a load-type event happening.

I hate to really crank on the belt tension. It's pretty darn tight now. I'm worried too about whether the load is due to a compressor bearing going bad. I'd space the fan a bit farther away but with the big aluminum radiator and fixed fan, I'm running out of space between fan and radiator.

The system seems to cool just fine. It's a converted r-12 to r134 set up.

Michael, what's up??

Thanks!!
 
What you are seeing regarding the york/cci compressor engagement operation is a normal occurrence. The belt tension on those units needs to be set around 150>160 pounds in order to reduce (not eliminate) "belt flop". That means really tight!

These units are a twin cylinder reciprocating unit, not at all similar in design compared to more modern compressors. On top of that, they are not "balanced" as part of their manufacturing process.

And, while the mounts appear to be very rigid (most are cast iron), in actuality they do allow a good bit of movement when the harmonics related to the compressor design kick in. And you are seeing all these conditions occur at certain engine rpm levels based upon the normal operation of these compressors. Many of the ihc compressor mounts had to utilize a "top" support from the compressor back to the engine as an attempt to stabilize these units but in my opinion those don't accomplish much.

In order to eliminate the compressor vibration issue, it simply needs to be replaced with a sanden, seltec/tama, etc. Aftermarket unit. Those are six cylinder linear oscillator units that are much smoother and more precisely manufactured. Those compressors also draw one-half the horsepower compared to the york! The york requires an average of 7hp, the japanese compressors use about 3hp!
 
The york on my 74 does the same thing.
As m/m stated you gotta crank on it and you May even need to go shorter on the belt. I had too!
My 74 has a straight drive fan on it with a 1" spacer, I'm going to a 2", this should allow enough clearance and stop the slapping or at least lessen the impact, I hope. Last time it caught up and cut the a/c belt which in turn took out the rest of them.
Hopefully I will get this little swap done this week and I'll report back.
 
Thanks guys.

I just thought it odd that the load would vary. The compressor only receives low pressure gas from the evaporator right? Unless it's like you say michael, some harmonic or something.

I'll crank that belt tighter. And yes, I May need a shorter belt! Running out of space for lateral movement!
 
The primary and secondary harmonics in the york compressor is pretty radical, along with the gross imbalance.

The compressor "converts" the low pressure (relatively speaking) liquid-entrained gas into a high pressure gas. That's quite a bit of work going on internally in a compressor that is really crude in overall design/construction.

We see exactly this same issue occurring no matter what engine these units are installed upon. They shake hell out of a 3406 cat diesel the same as an ihc sv.
 
Ok told yall I'd post back when the belts were swapped.
Couldnt use the 2in spacer as I thought, factory 1in in place with straight drive fan. Went with a 9525 belt , house brand from oreilly. Belt just barely went on the pulleys with the compressor slid all the way forward. Tightened the bejeezus out of it and it seems to work great. No more flop like the longer 9553 and the compressor seems and I stress seems to run smoother.
Try the shorter belt and see what happens, I drove mine for about 25 miles to get them hot and everything is good.
 
Brilliant minds think alike as they say....

I also chose the 9525 belt. I could get the 9520 belt on the pulley if I first dismounted it. But that close, the pulley and the inlet on my aluminum radiator are side by side. Too bad the radiator wasn't designed with a radius on that inlet corner. Oh well.

And I really tightened the belt. I still get some flop but no fan impact. I May tighten it some more, but the flat top of the belt is already just slightly concave in the pulleys. How tight can one go?? Dunno.

For other readers, the spec'd belt is the gates 9530. Minus 1/2" in circumference equates to the 9525. One inch and you have the 9520.
 
After 13years of trying to repair the a/c in my wife's dailydriver I replaced the compleat system with all new parts including a new york compressor but stil the vibration come back with the wamerweather ,what michal is saying the york 2cilinder compressors do not work with r134a gas. To retro fit a old r12 system the first thing to replace is the comp. I wish I had that info before I spent all that time and money .
 
Imho, an a/c compressor has no knowledge of what kind of refrigerant it is pumping through its pistons or rotors.
R134a and r12 are chemically different but are relatively close in the temp range they operate in.
As m/m ststed in the post he responded to, york compressors are not balanced internally and having only 2 pistons they do vibrate more than a sanden or a keiki compressor. York compressors vibrate when charged with r12 as well as r134a. The vibration is caused by the high pressures created when converting a low pressure gas back into a liquid. The york compressor can be and was used by many different manufacturers for years with both r12 and r134a.
So the belief that they cant be used reliably with 134a is totally wrong. If true, paccar,freightliner, IH, Ford and a few other automotive and heavy truck manufacturers would not have used them as an oem unit. And retrofitting these stone age style compressors is possible, the old one off my Scout is now running the a/c unit on a 78 Ford f150 with r134a in it and it works flawlessly!!!!!
 
Any current design mobile ac compressor will pump any common refrigerant just fine. The reason "some" were never used with r-134a (or many other refrigerants) is that a materials design issue was present, in other words, the internal materials used would not hold up to long-term testing needed to verify the compressor was suitable for some refrigerant other than what it was designed for.

The cci/york compressor is very crude in both design and manufacturing. But it holds up just fine to the abusive environment experienced in operating on hd trucks, offroad equipment, etc. Where vibration and noise are not really an issue. And today, they are still the least expensive unit out there when purchased in lot's of 1,000 at the oem side.

Ya want "smooth" and minimal hp loss, then do not use a cci/york!

By the way, any manufacturer of current compressors today also manufacture their own version of a twin cylinder/reciprocating compressor used for certain oem applications, transport refrigeration units, etc. But those compressors are never used in modern passenger vehicles.
 
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