Too much oil (or a really tight compressor) could cause a high torque issue at startup - which would cause the belt tension to go sky high & bang the tensioner stop.

If the clutch itself is actually making a banging noise, it is not right. So yes, swap it out before it does something worse.

Yeah, you will need to host the photo someplace else to post it on here. I have seen some ludicrous FMIC installations over the years here - with posters wondering why the A/C no longer works. With any sort of changes to the heat exchanger stack, it is always good to make sure the fan is pulling air...

If you are putting in a huge intercooler, you will need to be sure that the condenser airflow is not compromised. Using a larger condenser is a good plan, because of the increased air temperature at the face. Plenty of choices out there. CTS Cadillac condenser has been a good swap for me a few times...

I don't think I would charge an empty, unknown system. I would be inclined to pull the compressor & see if it has any oil in it. I know it is an E series, and a pain to work on. Perhaps pull the accumulator & check it for oil? Some of those vans had scroll compressors, others had the FS10 pi...

Just another kid with a sanden catalog , Tim. Interesting that one vendor caused the Original Poster so much trouble though. Supplied an inadequate compressor for a car that big, AND a "custom" defective evaporator. And the only way the OP got the the bottom of it was coming here - for free.

Gus:

You asked about Sin City. I have never heard a bad thing about them, and I think Chris keeps about half of the E30's in Las Vegas on the road.

If you replaced the tensioner 6 years ago, it might be time. Sometimes aftermarket replacements just don't last as long as OEM.

Try another gauge set. Your control system appears to cycle off at all sorts of different low side pressures. Either the switches / sensors are bad or your gauges do not repeat. Before you go after the control system, try a second set of gauges to make sure you are not chasing your tail. You have re...

What is the high side reading while it cycles?

BMW used a hydraulic tensioner for the belt in that car.

Open the hood, and locate the tensioner. Have someone start the car, then turn on the A/C while you watch the tensioner.

Absolutely. If you are finding bits of foam coming through the vents, something is failing.

Mitchell DIY subscription is $20 for a one month access. You get the whole factory service manual.

Well worth the price, you can save days of work on jobs like removing the a/c evaporator box.