So, what causes A/C black death, really?

Googling high and low brings, essentially, two reasons:

1. Compressor (FX15 model) shaving its internal teflon rings (which are black in color) into powder.


-- Engineer in me quietly, but confidently whispers that this is B.S..

2. Moisture gets into the system thru crack/hole/etc and refrigerant/oil decay*, forming acid. Acid eats aluminum, solder flux, etc, producing the "black death goo".

-- This sounded a bit more convincing - the more so that I know for sure that it is, indeed, acidic... until I realized that, in pressurized system, something could readily go out thru a hole, but never inside.

So I'm looking for other possible reasons ...and opinions.


________________________

* -- Great. Just great. 21-st century, and they still couldn't come up with refrigerant/oil which wouldn't react with water, producing - of all things! - acid.

The oils in 134A and good old freon are not compatible. Never really looked into the different chemistry. That was good enough for me.

Moisture does get in, any time the system is opened. This causes corrosion and rust. Usually the compressor secumbs first. If you ever open an AC system for anything, it needs a good long pump down and a new drier installed.

To prevent "Black Death", pump out Freon, run cleaning solution through entire system making sure to turn compressor over several times. Some people say to remove condenser and exchanger and clean aggressivly with AC cleaning solvent. Pump down system and hold vacuum at least several hours. Replace drier and reconnect. Pumpdown again for 2 hours. Install new 134A and proper amount of oil by weight per manufacturer specs. Test system. Check high and low pressures. Adjust 134A as needed. You are done. No Black Death. Usually!

joecrna said:

...
Moisture does get in, any time the system is opened. ...

Click to expand...

I understand this. However... here is my case.

Year ago my mechanic installed in my 92 Explorer brand new A/C system (every component, including compressor, was brand new, no rebuilds, and I bought them all myself, so I know). Some month ago high pressure valve blew up, then again and again - the system lost a lot of refrigerant, and severely lost efficiency, but it was still pressurized and producing some cooling when some week ago I opened it and replaced accumulator-drier and orifice tube - and there was black death goo on orifice tube, and the oil I pored out of old accumulator-drier demonstrated considerably acidic reaction.

Once again, the system was never opened, always pressurized - so how in the world piece name the moisture could get inside?

One note, though... since that time, a year ago, I did not do the original installation myself, my only bet would be that the mechanic, who worked on it, did not pull vacuum at all, so the moisture was in the system form the very beginning... I can not believe it, though - this guy was always thorough and honest before... so I'm looking for other explanations.

That would be my guess. Doesn't mean he isn't both honest and thorough, just not an AC expert. The pumps aren't that expensive but more then someone might spend if they rarely work on AC. Many AC service people fail to understand the impotance of pumping down and leaving it to vacuum for several hours. That explains the corosive nature of the liqued.

It does not explain the goo (black death). If he replaced it a couple years ago, it uses refrigerant 134A. And its associated oil/lube package. That must mix with the oil/lube from freon (12). Thats what came in a 1992 Explorer but you had him replace everything. Did this realy include every hose, hard and flexable. How about the condenser and evaporator. The evaporator can be a pain to get to, up inside the dash. If the refrigerant lines were not filled with the goo and the compressor did not sieze, you only had a little. Leads me to believe some section of tubing or a component was missed during the replcement.

joecrna said:

That would be my guess. Doesn't mean he isn't both honest and thorough, just not an AC expert. The pumps aren't that expensive but more then someone might spend if they rarely work on AC. Many AC service people fail to understand the impotance of pumping down and leaving it to vacuum for several hours. That explains the corosive nature of the liqued.

Click to expand...

Yeah... probably. I really, really don't want to think that he lied to me, but I simply don't know what else to think...

joecrna said:

It does not explain the goo (black death).

Click to expand...

Why not? As far as I understand, moisture causes refrigerant/oil rot, producing some acid, acid produces the black death goo.

joecrna said:

If he replaced it a couple years ago, it uses refrigerant 134A. And its associated oil/lube package. That must mix with the oil/lube from freon (12). Thats what came in a 1992 Explorer but you had him replace everything. Did this realy include every hose, hard and flexable. How about the condenser and evaporator. The evaporator can be a pain to get to, up inside the dash. If the refrigerant lines were not filled with the goo and the compressor did not sieze, you only had a little. Leads me to believe some section of tubing or a component was missed during the replcement.

Click to expand...

There was definitely no R-12 remnants in the system, it was retrofitted to R134a/PAG oil long time ago. Full systems history is like this:

Dark ages - 2004: R12, regular orifice, poor performance.

2004: Compressor seized. R134a/PAG retrofit, installed rebuilt compressor, new accumulator/drier, new hard lines both low and high sides, regular orifice, poor performance. No signs of black death.

2013: Compressor locked up. All components replaced with brand new. R134a/PAG, VOV orifice, excellent at highway, poor performance at idle.

2014: high pressure valve pops out. Replaced accumulator/drier, installed regular orifice tube. Presence of black death goo detected, oil pored out from old accumulator/drier shows acidic reaction.

And I'm pretty sure that, in 2013, all and every component was indeed replaced. First, I've got back every old component, second - it's enough to simply look under the hood to see they are all new, including evaporator - evaporators in/out pipes are fairly well exposed.

I'm cursing myself for not separating the installation and the charge... i really did not have the time then to do installation myself, but I could ask the guy to just install everything but not charge, and then do vacuuming and charging myself... Now I wouldn't have to think bad about the guy and fill bad because of it...

Only one thing I disagree with; my understanding about the cause of "Black Death" has always been that it is a mixing of the PAG oil used with R134a and the oil (it is different) used with R12. Don't know about the acid causing anything other than corrosion and rust, which usually kills the compressor and ultimatly other components.

Just my understanding and the reason for all of the AC flush used during the conversion from R12 to R134a.

joecrna said:

... my understanding about the cause of "Black Death" has always been that it is a mixing of the PAG oil used with R134a and the oil (it is different) used with R12. ...

Click to expand...

I've heard that, too... going like, R12 systems use mineral oil, which is to be said "incompatible" with PAG oil, typically used in R-134a systems.

But it does not explain my case: in 2013 all components were replaced with brand new, so there was absolutely no remnants of anything. After that the system was always pressurized (meaning there were no leaks, and moisture could not get inside) until I opened it some weeks ago and saw the black death goo on the orifice tube, and acidic oil.

Interesting write up never heard of the black goo here in Europe. When your AC was working did you clean the radiator and did your fan work well and did the AC lines become frosty and drip underneath?

From what I have read and seen, the "black death" is causes by the ability (or poor design) of the Ford compressors to keep running, even when there is a problem and the compressor is basically destroying itself. There is basically nothing in the system that tells the compressor to shut down if there isn't enough oil, if the seals are compromised, or even if there isn't enough refrigerant.

Also worth pointing out, the FX-15 compressor that came on the 91-93 Explorers is a very light duty design (hence it's small size) that really only works well with R-12.

When you just "retrofit" a 91-93 system by sticking R-134a into it, the higher pressures and incompatible oils often do have the effect of destroying the hoses, compressor, etc.

The "correct" way to retrofit a 91-93 is to use the larger FS-10 compressor that came in the 1994 and later models and is designed to handle the higher pressures of R-134a, along with the barrier hoses that trap the smaller R-134a molecules, and the receiver/drier, orifice tube, and switch for R-134a.

Rickademus said:

... When your AC was working did you clean the radiator

Click to expand...

Radiator was clean, it was about an year old at that time... and it's still fairly clean today.

If your mean condenser or evaporator - they both were installed brand new.

Rickademus said:

and did your fan work well

Click to expand...

No, the viscous clutch was shot years ago, and fan was not engaging fully, but enough for cooling the engine, even in Houstons summer heat.

I've replaced the fan clutch after the A/C high pressure valve blew - it did not help, but, at least, for future...

Rickademus said:

and did the AC lines become frosty and drip underneath?

Click to expand...

Yes.

Anime said:

... There is basically nothing in the system that tells the compressor to shut down if there isn't enough oil, if the seals are compromised, or even if there isn't enough refrigerant.

Click to expand...

There is a low pressure shutoff switch, and some systems have (aftermarket?) high pressure shutoff switch.

Anime said:

The "correct" way to retrofit a 91-93 is to use the larger FS-10 compressor that came in the 1994 and later models and is designed to handle the higher pressures of R-134a, along with the barrier hoses that trap the smaller R-134a molecules, and the receiver/drier, orifice tube, and switch for R-134a.

Click to expand...

Good notion... I'm not sure yet what I'll do to A/C when the time comes, but if I will be replacing the compressor (again! ) I'll take this into account.

Hoses are already barrier-type, drier has proper desiccant in it, orifice tube is for R134A... switch - I'm not sure it needs to be changed.

pkn said:

There is a low pressure shutoff switch, and some systems have (aftermarket?) high pressure shutoff switch.

Click to expand...

I don't think the 91-93 Explorer switch has a low-pressure shutoff, otherwise a lot of these issues wouldn't have happened. The switch mainly just tells the compressor when to engage/disengage to provide cooling.

switch - I'm not sure it needs to be changed.

Click to expand...

There is a R-134a-specific pressure switch for the Explorer. R134a operates at different (higher) pressures then R-12.

If you use the stock R-12 switch with the FS-10 compressor and R-134a in the system, it's not going to work correctly.

It may still work and appear to be ok, but I'd say it's not worth the risk of anything happening for a $5-10 switch.

Anime said:

I don't think the 91-93 Explorer switch has a low-pressure shutoff, otherwise a lot of these issues wouldn't have happened. The switch mainly just tells the compressor when to engage/disengage to provide cooling.

Click to expand...

Hmmm... You've got me thinking. But isn't this is how it works?

Switch is mounted on receiver/drier, i.e., on low side. When system is off, the pressure is equalized between the high and low sides, so at low side pressure is higher than during operation.

So when system starts, pressure at switch lowers, and if there is not enough refrigerant, it goes too low and switch shuts of. Which makes it low-pressure shutoff switch.

Anime said:

There is a R-134a-specific pressure switch for the Explorer. R134a operates at different (higher) pressures then R-12.

If you use the stock R-12 switch with the FS-10 compressor and R-134a in the system, it's not going to work correctly.

It may still work and appear to be ok, but I'd say it's not worth the risk of anything happening for a $5-10 switch.

Click to expand...

Your are right, and when (and if?) I'll be redoing my A/C again, I'll try to get FS10 compressor (is it direct replacement? If I, say, order compressor as if it is for Explorer 94-96?) and the proper switch to pair with it.

pkn said:

Hmmm... You've got me thinking. But isn't this is how it works?

Switch is mounted on receiver/drier, i.e., on low side. When system is off, the pressure is equalized between the high and low sides, so at low side pressure is higher than during operation.

So when system starts, pressure at switch lowers, and if there is not enough refrigerant, it goes too low and switch shuts of. Which makes it low-pressure shutoff switch.

Click to expand...

That is how I understand it works, so yes, low refrigerant will make it cycle but not outright stay off unless it is extremely low.

<snip>when (and if?) I'll be redoing my A/C again, I'll try to get FS10 compressor (is it direct replacement? If I, say, order compressor as if it is for Explorer 94-96?) and the proper switch to pair with it.

Click to expand...

AFAIK, yes BUT they re-routed the hoses on newer explorers. They used to go around the back of the engine and now go under the Throttle body.

I found a local shop that will sell me all of the a/c parts for a 1994 explorer, including hoses, receiver/dryer, evaporator,condensor,o-rings,compressor etc for $550 and more importantly, lifetime warranty (parts). That's a fs10 system. I have found other places about the same price (even a little cheaper) but not with the lifetime warranty.

Hm... interesting. I've searched where did I buy the compressor and found that bought it at Amazon in 2011 (for $190 and now it's $266 )

It's Motorcraft YCC154. Can not find if it's FX15 or FS10. However, the Amazon part fitting system says it does fit 94 Explorer XLT. Does it make it an FS10-type and completely suiteable for R134A?

pkn said:

Hm... interesting. I've searched where did I buy the compressor and found that bought it at Amazon in 2011 (for $190 and now it's $266 )

It's Motorcraft YCC154. Can not find if it's FX15 or FS10. However, the Amazon part fitting system says it does fit 94 Explorer XLT. Does it make it an FS10-type and completely suiteable for R134A?

Click to expand...

I just did some quick google-fu and it appears the fs10 is a direct replacement for the fx15 AND re-builders only do fs10 and list them as fx15/fs10.

~Mark

Maniak said:

AFAIK, yes BUT they re-routed the hoses on newer explorers. They used to go around the back of the engine and now go under the Throttle body.

Click to expand...

Are you sure it's not vice-versa - older, not newer, does go under the throttle with distinctive V-shaped part of the hose?

I'm asking because mine (92 XLT) definitely goes V-shaped under the throttle, and it was always like this since I bought the truck in 1999 or 1998...

It's possible, of course, that one of the previous owners did the change...

Our '92 went around the back until sometime in the early 2000's when I first fixed the a/c system and the new line went around the front and they couldn't get me the kind that went around the back without spending a bunch more.

I just did a quick google search and when I search for 1994 engine bay and look at all the pictures of 1994's every one is under the TB but when I looked at 1991's there were some around the front but there were also some around the back which is how ours "was".

~Mark

Ah! Then it's probably just a sub-year sub-model difference... Otherwise I would have to believe that one of the previous owners did actually do something on the truck - and that's something I find really hard to believe in!

pkn said:

Hmmm... You've got me thinking. But isn't this is how it works?

Switch is mounted on receiver/drier, i.e., on low side. When system is off, the pressure is equalized between the high and low sides, so at low side pressure is higher than during operation.

So when system starts, pressure at switch lowers, and if there is not enough refrigerant, it goes too low and switch shuts of. Which makes it low-pressure shutoff switch.

Click to expand...

That's how newer systems work, but the switch setup and compressor this system uses is older and, in my experience, the system will run no matter what, even if the system is empty. That's exactly why these systems and compressors get "black death" - they will disintegrate and run themselves to death because the system has nothing to prevent it.

Your are right, and when (and if?) I'll be redoing my A/C again, I'll try to get FS10 compressor (is it direct replacement? If I, say, order compressor as if it is for Explorer 94-96?) and the proper switch to pair with it.

Click to expand...

As mentioned, the FS-10 is a direct replacement for the FX15, it's just bigger and heavier.

You can only buy the FS-10 now, the FX15 was discontinued long ago and all you can buy are remanufactured units, or maybe some China-made new ones.

Just be sure you buy a compressor with the pulleys and clutch attached. Ford sells them with and without the pulley/clutch, and it costs about the same or sometimes less to get the one with the pulley/clutch.