View Full Version : A/C Experts Please !

Les Borda
07-09-2002, 07:10 PM
Ok here is the situation, after blowing the suction line on my A/C at the joint where it switches from metal to rubber( it was somewhat rusty). I changed a bunch of stuff.

New suction line, receiver dryer, liquid line(or orifice line).

Converted to R134A. (Prior to this I allowed some idiots in an AC shop to put in leak sealer and recharge with R12, never mind where I got it...shhhhhhhhh.)

All seals are the correct green ones. After charging the mechanic was looking at my pressure on the high side, he thinks there is a blockage yet it is cooling very well. My high side reading at idle was around 270lbs. The ambient temperature was 95 degrees, the mechanic said high side readings should equal 2 x ambient temp + or - 10lbs. I should have been reading 200lbs max according to what he said.
This fellow does not and will not use leak sealer in any of his customers AC units, he says it seals alright and can block other little holes that are required, like in the evaporator and condensor.

So AC dudes what kind of high side pressures are you running? Am i in spec or is it truly running to high?

07-09-2002, 08:19 PM
I think the number they use is actually 2.4 times ambient. So 95x2.4 = 228. So, if you're running 270 at idle, this might indicate blockage in the condensor or a clogged O-tube. Maybe its the sealer; I personally wouldn't use it either.

Did your compressor go out? The Ford FS10 compressor suffers what they call the black death, and the repair for such a failure is a big job.

Here's just one of many discussions about it:

You should find out just how high the high side is going when the engine is running at 2000 RPM.

Joisey Jim
07-09-2002, 10:25 PM
Les - If I recall correctly my chart shows atleast 260psi on the high side @ 95 deg. So it doesn't sound like you're way off the chart. Did you, however, remove all the old oil in the condenser & compressor, add the newer 'ester' oil for 134a and, thoroughly vacuum down the system to boil off any moisture before the re-charge.
The black death that they refer to I believe is either old oil in the system or moisture turning the refrigerant into acid and corroding the inners.

07-10-2002, 01:10 AM
Actually Jim, the Black Death is compressor innards and Ford FS10, FX15s in particular are known for it. My new compressor specifically mentioned the FS10 and some other GM compressor as requiring a new condenser for the warranty to be any good (lame 1yr warranty anyway so why bother). Its due to crud which possibly can't be fully flushed from a parallel flow condenser which of course is what the 90 came with. So, I spent the $$ and put in a new condenser also. Shoot, the ONLY thing I reused on my repair/retro was the suction line/manifold/high line and that's because I could flush it. The evaporator had a leak which is what fried my compressor to begin with.

None the less, the experts all agreee that the best thing to do on a retrofit is: new accumulator/drier, new orings, (recommend new Otube), thorough flush, new oil, vaccuum, charge into the vaccuum, and finish charging using a full set of guages. The vaccuum is a must otherwise any moisture can combine with PAG/POE and form an acid. And an old saturated accumulator is risky insurance against that. Its also possible the dessicant is not compatible with r134a.

If you don't do all that stuff, it might work OK, but its just chancy. That's why they frown on the Walmart death kits. The only thing the kits provide is fittings, oil, refrigerant, and a cheapo low pressure guage.

Les Borda
07-10-2002, 07:10 AM
I did replace the manifold/suction line I had no choice it was kakked, new O-tube and receiver dryer. They did pull a vacuum on it for a good 45 minutes and added 4 oz of the new ester oil. We did not flush the condensor or evap because this particular shop does not have that type of equipment.
The old compressor survived the blow out and is currently running nice and quiet.

Jim it sounds as if my high side pressure is within spec according to your numbers.

07-10-2002, 02:02 PM

If your suction line was caked and your compressor was OK, the only place where the crud could come from was the dessicant bag in the accumulator. They can rupture. While your compressor may have survived OK, I'm 90% sure that the crud got shoved into your condenser..

Take a look at your old Otube (or try to blow through the old liquid line).. I'll bet its clogged with melted dessicant. You can also look at your old high pressure line which is part of the old manifold. If there is crud in there, theres crud in your condenser.

If this is the case, you should seriously consider flushing the condenser (or replacing it due to the risk+time+material factor involved). If its working OK, I can't tell you how much time you have, it could be your system will run fine for the rest of the year, but I'd definitely look into it by next spring.

Here's a link I found where the experts can tell you more than I. There is a very useful archive section, and If I'd know about it earlier, I could have found better quality parts.


Les Borda
07-11-2002, 07:07 AM
Thanks for that great link!!!

When I took out the O-tube I did blow through both ends and it was free and clear, but I changed it anyway seeing as I had everything pulled out at this point.

I think I'll take your advice and start checking around for prices on new condensors. At this stage it is not a big expense to change it and recharge, it may save me some grief down the road.