The clutch is good because it engages the compressor. The controls that engage the clutch are questionable, I'd expect at the pressures you have that the clutch would be disabled. I bring it up because if you run it for long like that, you risk tearing up the compressor. It relies on gas circulation to return oil to the compressor sump. When I got my SDL, the Klima relay was stuck closed, so it ran the compressor with no refrigerant and burnt it up. That happened long before I got the car. The compressor was a write-off and the system was a mess. Don't let yours get to that point, it's a lot of extra work that doesn't need to happen.

If you want to do a quick gas & go, buy a couple cans of R12 and top off the charge. See how long it lasts before it leaks out again.

If you're going to have the system recovered and filled with new gas, you might as well do the job right. Flush the system out, replace ALL of the O-rings (they're a common leak point), replace the expansion valve with a new one (all the new ones are R134a rated), install a new receiver-dryer, and replace the fan switch and pressure switch on said receiver-dryer (the newer switches have pressures matched for R134a). Pull a deep vacuum, dump in some PAG oil and refill with R134a. The small-tube condenser on the Gen II 126 works fine with 134a, and when matched with the correct expansion valve, the system works very well.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]