"I am not an A/C mech, probably barely qualified to pass the EPA test, on a good day,..."

I'd say you fake it pretty good for someone who supposedly doesn't know much. You can sure explain things better than I can.

Mr Ski,
It's very likely that the orifice tube shot down into the evaporator. That can happen if debris clogs the screen and excessive pressure builds up behind it. It's not really common, but I see it happen about 1-2 times per year.
I see it most when someone replaces a failed compressor without flushing all of the debris from the condenser. The old debris clogs the tube and the fresh, tight compressor compressor keeps trying to push refrigerant through the system.

 

The switch is stamped on at 45 PSI, off at 24 PSI. I looked up the freezing point of R134 and it is about 28 PSI. So R12 is a little lower. I can't imagine ever running this thing so cold to get the pressure that low. It's just to damn hot in Phoenix.

But something happened yesterday. Leaving work at 4:30, about the hottest part of the day, system pressure got so high it popped open the pressure relief valve on the back of the compressor. The suction/pressure line attaches to the back and there is a little valve on the block of the hose where the o-rings are. It shot a stream of oil to the firewal and left a nice coat all over the EGR components.

Got it home and hooked up the gauges and fired up the engine. Pressure on high side started to creep 350...375 and low side well over 50 PSI. So I shut it down for a minute then tried it again. This time I cranked the fan to high and hosed down the condensor with the garden hose. Pressures settined down to abotu 225 on high and 35 on low...varrying the load on the system with the fan and the garden hose trick, I could move the pressures up and down and they stayed in the "safe" ranges on the gauges.

I don't know if I had too much freon in there or if R134 is just that tempermental. When the relief valve blew, I didn't have the fan cranked all the way. Maybe on startup when the car is about 1,000 degrees inside I need to crank the fan no matter what. I think I lost about 1 oz of oil with this. I'll continue to monitor the pressure and if I can get away with a little more freon, I'll add some of the stuff that has oil in it already.

 

This is probably what happened. I didn't have a good way to flush the condensor. The previous compressor did lock up and i replaced it. So that is why this time i replaced everything in the system...did not want to mess with this forever again I guess. 206K miles on this thing...time for a new one anyways.

 

x101: isn't Lorain county just west of cleveburg? Where they usta put together Econoline vans? I remember (-35 years) traveling out that way whilst in USN at NavFinCen. And traveling back in my brand new Ford from NEMET, delivered for $14 to Dearborn, MI for pickup. And coming upon an Ohio State Trooper roadblock. They waved me through in my new car. Gas was 57.9 and I thought it high. Oh, to be back there and have some of my current store of experience. Waaay off T.
Funny thing here is that the plugged orifice did not make the HP relief valve go blammo. Maybe there was not one fitted... They were not so common on R12 systems if my grey cells are functional.
One of my brothers had a black death Ranger. He tried to make it work, bought a new HP relief valve, evacuated, charged and had cool air. Until the next time he tried it, when the goo finally blocked flow again. I now know how Freon was used to make Styrofoam cups. Mix that stuff into the poly under pressure, and when it gets out, it makes all kinds of little bitty bubbles in whatever it is currently embedded. We must have had a gallon or so of foam 'rustproofing' his truck. I had told him it wouldn't work, but he had to learn on his own.
tom

 

The old line does have a P relief valve. I checked yesterday. Maybe the new one is bad? I did verify with the gauges that P was too high....I'll just see what happens going forward.

 

"x101: isn't Lorain county just west of cleveburg? Where they usta put together Econoline vans? I remember (-35 years) traveling out that way whilst in USN at NavFinCen."

It sure is, about 35 miles west. Ford built Econolines, Falcons, Fairlanes, Torinos and then Thunderbirds there back in the day.
Sadly, the Lorain Assembly plant was closed back in about 1997. It's kind of ironic; I stored my daughters Chevy El Camino there last winter and much of the outside area is full of new Hondas right now. Sad.

I'm familiar with your neck of the woods too. I have family in Atlanta, Cartersville, Marietta and over in Rome and Tallapoosa. (Mom was born in Rome and raised in Linndale). My daughter attends college in Valdosta. Small world, huh?
By the way, the W in your name wouldn't happen to stand for Wilkerson would it?

"And traveling back in my brand new Ford from NEMET, delivered for $14 to Dearborn, MI for pickup. And coming upon an Ohio State Trooper roadblock. They waved me through in my new car. Gas was 57.9 and I thought it high. Oh, to be back there and have some of my current store of experience. "

Yup.


"Funny thing here is that the plugged orifice did not make the HP relief valve go blammo. Maybe there was not one fitted... They were not so common on R12 systems if my grey cells are functional."

Actually, most R12 systems had a relief valve. They're not allowed on R134a systems. They've been replaced with a High Pressure Cutout switch to prevent venting refrigerant into the atmosphere. It's not uncommon for the valves to get plugged with rust and not open.


"One of my brothers had a black death Ranger. He tried to make it work, bought a new HP relief valve, evacuated, charged and had cool air. Until the next time he tried it, when the goo finally blocked flow again. I now know how Freon was used to make Styrofoam cups. Mix that stuff into the poly under pressure, and when it gets out, it makes all kinds of little bitty bubbles in whatever it is currently embedded. We must have had a gallon or so of foam 'rustproofing' his truck. I had told him it wouldn't work, but he had to learn on his own."

Yes, Black Death is quite nasty. I'm glad those FX-15 compressors are far behind us now.

Regards, Tom A.

 

Mind plays tricks. Of course the R12's had a popoff. This Ranger was an R12 system. DUh.

tom in Canton

 

My pressure relief wont rust..it's brass. I tried backflushing the old evap core with water...got a few little pieces of plastic out. I'm thinking more like that Napa shop remover the orifice tube...jury still out.

 

If I remember right, sometimes on thoses old fords the dessicant bag in the accumulator would break and clog up the metering orfice. I never heard of them shooting down into the evaporator though. If you do not have a metering device some liquid refrigerant may make it into the compressor and as we all know a liquid cannot be compressed, and valves or cranks break, or the compressor just locks up. If the popoff valve is opening you probably have it over charged. I have a couple of old cars that I converted over to 134, a 1970 torino that only takes about 8 or 12 oz. of 134 to operate, and a 1978 t-bird that uses 60 oz. of 134 to operate, go figure. I think I bought the lines from classic car a/c online, and they can tell you how much refridgerant to put in your particular vehicle. Isrx101, what is a emd 8-a?