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Trying to recharge, compressor short-cycles


96firephoenix

Well-Known Member
Joined
Aug 20, 2014
Messages
193
City
Indianapolis, IN
Vehicle Year
1997
Transmission
Manual
(1997 Ranger XLT 2.3 w/ Factory AC) So I got a manifold gauge set and pulled a vacuum on my system, then put some R134 with lubricant in it into the system.

System reads 50 psi on the low side, and 100 psi on the high side at engine idle, but then the compressor kicks on and they go down to about 30/50 psi.

The compressor is short-cycling and coming on really hard. By that I mean that it cycles for 3 seconds, rests for about 10, and cycles again, and after about 4 iterations of this, it is almost stalling the engine when it kicks on.

The system held vacuum while I was checking it, and still was charged from the other day when I tried just pushing R134 in on a not-vacuumed system.

What am I missing? I followed the charge procedure after replacing the Drier/Accumulator (some idiot put a thermal blanket thing on it trying to prevent condensation, but all that did was trap the condensation and rust out the drier :icon_thumby: ). I did a little bit of looking over the Auto AC forum and can't seem to find any answers (I admittedly suck at searching, so there's that).

I'm starting to think there may be something electrical like a sensor (yes, I plugged them back in) or a relay. Could there be something wrong with the compressor itself?
 
If the compressor is putting so much load on the engine it's almost stalling, then it's something either wrong with the compressor, or you've got contaminants in the system or too much oil or ? (too much oil is quite likely if you added oil & freon on top of whatever was already in there).

I suggest disassembling everything and doing a full flush on both cores. If you find the oil is also black & cruddy, then both the compressor and condenser core will need to be replaced (along with the normal stuff eg.: accumulator, orifice tube, & o-ring seals).

And FWIW, the "idiot" that insulated the accumulator was probably Ford.
icon12.gif
They've been doing that at the factory (along with insulating the evaporator box) since mid-year '94 models to improve the overall efficiency of the A/C system.
 
Yummy, that's what I was afraid of... I was going on the assumption that since the drier can was open, there was not any oil in it. there was 0 psi in the system when I started this process. Your comment about if the oil is bad, I should replace the condenser and accumulator... Is that still the case on a brand new accumulator?

Seeing how much compressor flushes cost, I think I may be better off just replacing the compressor and orifice tube and see if that does the trick. Would be the same amount of money getting RockAuto parts, and barring a leak in the lines somewhere, that would be all the mechanical components. Then if that doesn't work, I'll start replacing sensors.

I was assuming it was some random idiot because it was held on with a zip-tie and applied over the clamp - did not look like factory fit or finish.
 
Could be someone R&R'ed the insulating blanket and when they put it (or a new one) back on, they may have did it however they saw fit... Hard to know for sure. Ford began insulating things when they switched from R-12 refrigerants to R-134a. I can't recall if they used something resembling ordinary zip-ties or if they had straps made specifically to go around the accumulator.

Anyway... Oil that is black/contaminated with debris (usually from a failed compressor) means pretty much every component of the system, aside from the evap coil, should be replaced (any relatively-new hoses that DO NOT have an inline muffler should be ok to reuse also). Reason for this is the difficulty of flushing every bit of debris out of the "pockets" inside the condenser coil and inside mufflers. Such debris can (and often does) lead to subsequent failure of a new compressor.

If the oil and insides of your system are clean, then you probably could get away reusing the accumulator you have. The compressor should be dismounted, turned over & rotated to expel all the oil out of it, however I don't think flushing out the compressor is necessary (again, this is only if everything looks clean).

Much of the leftover oil is often inside the condenser. Without flushing it, there's no good way to know how much leftover oil there is (plus it's usually better to have nice fresh oil anyway, not unlike putting fresh fluids in for the rest of the vehicle's systems)
 
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System reads 50 psi on the low side, and 100 psi on the high side at engine idle, but then the compressor kicks on and they go down to about 30/50 psi.

So the pressure drops from 100 psi to 50 psi on the high side when the compressor kicks in? Sounds like a low charge.

You said you put "some" freon in... How much is some? The correct amount?
 
The high side should not drop once the compressor kicks on. Typically if the pressures are fairly close or equal with the compressor running then it is usually the sign of a failed or failing compressor. What is the ambient temperature in your area? What is static pressure on the gauges with the truck off after it has sat for a while?

Did you charge it through the low side with it running or off? How long did you vacuum the system? How long was the system open before repairing it? Sorry for all of the questions, but I work on ag equipment and do a lot of A/C work and I'm curious to find out why the high side is dropping.
 

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