(update)
Ok, they are saying it has a blockage somewhere. They did infrared sensor readings, sent them back to the Natn. Honda tech people who are NOW wanting further tests done on the Compressor and on the Condenser.
They gave me the car back, I have not paid them anything except for the original conversion, and we have put off working on it until Mon/Tue.
I took it to another shop that hooked it up and looked at the pressure in the system.
At idle it is...
High pressure 115 psi
Low pressure 60 psi
When you throttle up the engine the low pressure drops and the high pressure raises.
(significant both)
I might add that the compressor is NOT cycling during this and that the AC Fan is working fine.
THAT guy said that, to him and with those psi readings, either the Compressor is going bad OR the dryer is clogged. Normally when the compressor is bad both high/low are the same readings. He told me my high wasn't high enough and my low not low enough. So in his opinion it is indeed a blockage somewhere, and he thinks the dryer, or that compressor is starting to fail.
I guess it all boils down to what caused the blockage. If when they originally converted it, vac. out the AC lines caused some debris to dislodge and cause the blockage, would that be THEIR fault or just an "act of God". Was their something they failed to do properly that I can trace directly back to them or is this just something that "happens" and I need to either pony up a ton more $ or not have AC this summer.
All in all this has been quite frustrating.
man i'm waaay late on this one.
depending on temp, and humidity, your pressures should be(at idle) around 30-40 psi on the low side, and anywhere from 150 to 250 psi on the high side. the 250 reading would be on an extremely hot/humid day.
the readings above show a restriction, probably the oriface tube or expansion valve...whichever your system uses. 60 is WAY too high on the low side, and 115 is WAY too low.
the high pressure blow off valves generally will not blow out till the pressure is over 300 psi.
as for blockage, there's generally 2 common areas, depending on how this system is set up.
1) if you have an expansion valve, find it, and tap it with a small hammer. if it brings pressures into range, then you have a bad expansion valve.
2) if you have an orifice tube, just take it out and put a new one in. they have filter screens built into them, and sometimes as they age, they will clog, causing a restriction.
you stated that you were driving when it blew. forget the fan. if you were moving, then you had air going through the condenser, and the fan is a non-issue at that point. even if it were sitting still, and the fan not running with the a/c, you'll still not generally get enough pressure to blow the blowoff valve.
someone else mentioned about converting........the conversion is crazy simply, and more than likely you could've done it yourself. it requires nothing more than placing the proper fittings on the lines for the r-134a, and installing ester oil, as the mineral oil that's used with r-12 will not be carried throughout the system. sometimes, if it's an older system, you'll want to replace the accumulator too.
hope some of this helped.
