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AUTOMOTIVE AIR CONDITIONING
TROUBLE SHOOTING GUIDE
If you haven’t heard the term “Black Death” then you haven’t experienced a compressor failure on a Ford with an FX 15 or FS 10 compressor. While not unique to Ford, “Black Death” seems to be most prevalent on Ford vehicles which use these models of Nippondenso compressor. Another compressor known for this “syndrome” is the Calsonic DKV 14D series of compressors mostly used on Isuzu’s and Nissans.
What is “Black Death”?
The Ford Nippondenso FX and FS series are 10 piston / 10 cylinder compressors. As such, they can be quite persistent little buggers, refusing to give up the ghost when they fail.
A typical failure mode for these is when a piston to throws a ring and the compressor continues to happily pump along on the 9 remaining cylinders. Now, the damaged aluminum piston continues to reciprocate in the aluminum cylinder sans ring and grates itself into oblivion. Meanwhile, there are bits and pieces of pulverized Teflon from the piston ring circulating through the system and they begin to mix with the grated aluminum. Not good. Combine this with the systems oil (which will soon begin to burn) and a sludge forms. The sludge circulates throughout the system, clogging orifices and generally impeding the flow of oil. This in turn causes the compressor to run even hotter, courtesy of the now impaired oil flow and the friction generated by the ring less piston, which is still quite efficiently grating itself to nothing. As if this isn’t bad enough, eventually a second piston ring will be thrown. To its credit, the FX or FS series compressor will just keep happily pumping along. |
So now we have a 10 cylinder compressor running on 8 cylinders with 2 pistons busily making this destructive paste of ground aluminum, pulverized Teflon and burned oil. At this point the owner is noticing the vehicle is not cooling as it should, but, it is still cooling. So he may choose to ignore it, or even worse, attempt to fix it with anyone of a variety of misdiagnosed repairs. Ultimately, the compressor will seize. By the time this happens, our little witches brew has cooked itself into something that has been aptly named “Black Death”.
The name fits because the ailment is almost always fatal. There is no cure.
To properly service a system infected with “Black Death” and consistently get a trouble free result, you must follow the “Change Everything Under The Hood and Vigorously Flush the Rest” rule.
I know, it sounds a bit extreme, but remember, a proper compressor installation requires you also change the receiver drier / accumulator and the orifice tube in a CCOT (Clutch Cycling Orifice Tube) system. Everything under the hood only adds a condenser to it.
When one considers the labor, time, and chemicals expended on trying to clean a condenser that is virtually impossible to clean, buying a new condenser no longer seems to be that great of an expense. As a matter of fact, it is almost seems cheap, especially when you know it will insure a good outcome, something you cannot accurately predict when using a flushed condenser.
Some will swear they can get the condenser clean. You will be told how they flushed it some ungodly number of times and everything was fine. They are not lying. What they do not realize is that *even* if they can get the condenser to flush clean, they can’t remove the burned oil, aluminum and Teflon varnish like coating on the inside and the coil will *never* dissipate the heat properly. It will work well in the cool weather and in the rain, but at best be marginal on a hot summer day.
For any system with “Black Death”, the proper service procedure is to change the compressor, change the drier or accumulator, change the orifice tube and change the condenser. Then flush everything that remains, paying special attention to the hose mufflers if there are any.
Mufflers have a special affinity for collecting debris and a cursory flush WILL NOT clean them. They need to be filled with flush, allowed to soak and, then blown dry with high pressure air or nitrogen. Once is not enough. It typically needs to be done several times.
Everything discussed above with reference to the Ford FX 15 and FS 10 compressor holds true for these little gems made by Calsonic.
The DKV 14D is a “rotary vane” compressor. Internally is comparable to a turbine. It consists of a shaft with a slotted rotor which sits inside an out of round cylinder. The rotor is positioned closer to one side of the cylinder than the other so as it travels its path around the cylinder, its distance from a fixed point on the rotor to the cylinder wall is constantly changing. Where the rotor comes closest to and farthest from the wall is where the suction and discharge reed valves are placed.
Remember we said the rotor was slotted. Inside those slots are highly polished, closely fit “blades” or “vanes” with straight but beveled edges. When the rotor spins, centrifugal force throws the vane against the cylinder wall. As it follows its path around the wall the vane moves in and out of the slot as the distance from the wall changes. As it passes the suction reed the valve opens and allows Freon to enter the chamber. As it travels around the cylinder the distance from the wall decreases, ergo the space diminishes also. This causes the Freon to continually compress until it reaches the point of maximum compression, where the vane is closest to the wall and where the discharge reed is located. The valve opens and allows the Freon to escape the compressor and follow its path to the condenser.
Sounds pretty efficient, eh? Well it is. Sounds pretty bullet proof too, doesn’t it? Well ....it could be.
The DKV 14D has an aluminum cylinder, unlike its predecessors the DKV 14C and the Nihon NVR140S, both of which had steel cylinders and were quite robust. The aluminum cylinder is fine, until, for any one of a myriad of reasons, the compressor gets overheated, starved for oil or is the recipient of a small piece of debris in any form.
This causes the vanes to slightly score the wall in their trip around the cylinder. Remember Fords aluminum piston sans ring in the aluminum cylinder mentioned above? Well the same situation exists here. The vanes start to act like lathe bits and peel tiny amounts of aluminum off the cylinder wall, thus creating a slightly different, but just as noxious brew of burned oil and aluminum paste which is just as impossible to effectively remove from the condenser.
For these compressors the “Change Everything Under The Hood and Vigorously Flush the Rest” rule also applies.
All flushes were not created equal. Avoid oily flushes and anything that does not quickly evaporate. The best cleaning agent in the world is useless if you cannot remove it from the system. A flush must be an effective cleaning agent AND evaporate quickly. Unfortunately, a good flush is also usually a highly flammable, nasty solvent.
For those reasons alone, it is usually more prudent to replace a condenser than to flush one, especially if you do not have the proper equipment and suitably ventilated area to do this.
One Last Word About Flushing
BE AWARE THAT WHEN YOU BLOW THE FLUSH OUT OF THE COMPONENTS A CERTAIN AMOUNT WILL VAPORIZE AND BE VERY PRONE TO EXPLOSIONS AND FLASH FIRES. A HOT LIGHT BULB OR A SPARKING SWITCH CAN CAUSE A VERY UNPLEASANT, EVEN FATAL EVENT. DON’T BE PENNY WISE AND POUND FOOLISH. IF YOU AREN’T SURE DON’T DO IT.
CAVEAT EMPTOR
IF YOU CHOOSE TO IGNORE THE ABOVE ADVICE AND INSTALL YOUR NEW COMPRESSOR WITHOUT FOLLOWING THE ABOVE RECOMMENDATIONS OF "CHANGE EVERYHING UNDER THE HOOD AND VIGOROUSLY FLUSH THE REST" WE WISH YOU THE BEST OF LUCK. WHILE WE SINCERELY HOPE YOUR PROJECT IS A SUCCESS, PLEASE NOTE WE CANNOT WARRANTY FAILED COMPRESSORS INSTALLED IN THIS FASHION. CONTAMINATED COMPRESSORS, BURNED CLUTCHES AND OTHER FAILURES CAUSED BY THINGS OTHER THAN LEGITIMATE MANUFACTURING DEFECTS CANNOT BE WARRANTEED.
