Any A/C experts? Blew off high pressure hose from compressor

[Raydar]

Coming home from Indy, it sounded like an M80 went off under the car. Lots of smoke. A/C quit working.
I discovered that the high side (discharge) hose actually slipped out of the crimp, just after the "muffler" in the line. (Made a hell of a noise.)

What is likely to cause this? I'm thinking there's an obstruction somewhere. Please read on...

The last time I had the orifice tube out, the fluid was very dark, but there were no solids, and the tube wasn't blocked.

Background...
It's a 4.9 conversion. Uses the Caddy compressor. Everything else looks to be stock Fiero. There are no pressure switches on the compressor. The only compressor connections are to the clutch coil. Still have the low pressure switch on the accumulator.
When the compressor cuts off, the low side pressure seems to be extremely high. When it kicks on, the pressure drops to normal levels (well... before it blew the hose off, anyway.) Don't know if that's significant or not. IIRC, it's always been that way.

The system seems to have lost some efficiency over the years. Before I found a leak near the orifice tube, it has typically required a recharge every summer.
The compressor still dragged on the engine when it kicked in, so I have to believe it's working. Before the hose blew off, it was cooling fairly well.

Anyone? Any help will be greatly appreciated.

[TopNotch]

Maybe your high pressure limit switch (usually on the compressor) didn't work.
Your fluid shouldn't be black. Maybe you need to flush the system. At least, check your orifice tube again.

[Fierofool]

I know little about AC, but I'll relate what happened shortly after I got the 87.  Maybe you might find something helpful.

I got the Big Bang, too along with the accompanying cloud of 'smoke'.  I got off the road and out of the car before it was stopped.  I thought I had blown an engine and caught fire.

In my case, it blew the pressure switch in the back of the compressor, spraying oil on the converter and along with the accompanying Freon cloud, I thought I'd just lost my new toy.  It actually stripped the groove where the snap ring sits.  Turned out the orifice tube was clogged and the cycle switch was also defective.  They said it looked as if the vanes in the compressor had degraded over time and plugged the orifice tube.  The cycle switch was still working, but not at the right pressure points. 

[Raydar]

An update...
Turns out that the stock Caddy uses a high-side temperature sensor that talks to the BCM, instead of a high pressure switch. The BCM then shuts off the compressor. (Leave it to GM to replace a simple switch with a freakin' computer.) It also uses a low-side temp sensor to cycle the compressor.
Of course, the BCM was eliminated when the engine was swapped in.
Guess what else was apparently eliminated? Any other high-side protection. (Where's the "wtf" icon when we need one?)
Well, other than the pressure release that is built into the compressor. 
Looks like my hose vented before the compressor had a chance to, but there still may be a blockage in the system.

[Fierofool]

Where are the temperature sensors located?  In the coolant lines or in the air flow stream?  Is that part of the dual comfort systems where the passenger and driver can adjust for their own personal comfort? 

Duh!  Never mind.  I see that you said they're located in the high and low side lines. 

[Raydar]

Where are the temperature sensors located? ...
Duh!  Never mind.  I see that you said they're located in the high and low side lines.

That was what I was able to gather from a quick look at the Caddy manual. Please don't hold me to it.
My point being that all that stuff got ash-canned when the engine swap was done. There is no high pressure protection on the swap, other than the high-pressure blowoff in the compressor. Nice.