Anyone have any thoughts on this...

I did significant work on my AC about 3-4 years ago on my 87 300D W124 (evaporator failed) Also replaced expansion valve, all rubber hoses, compressor seals and all other seals. Did not replace 100% metal tubes, condenser, or compressor.

Recently I noticed that it wasn't cooling adequately and there were lots of bubbles - I added dye and recharged w/ 0.8lbs. Also identified at that time that the red pressure switch had failed, it was no longer turning on the fan (fan works when switch bypassed, switch does not come on at 230+ psi.) I've jumped the red switch so the aux fan comes on 100% of the time that the key is turned on to avoid stressing the AC until I get everything fixed.

I have been unable to identify any leaks with either dye or an electronic leak tester. I've run it for 30 min in the garage, and driven for 75 miles and then looked several times. Although there are a few bubbles in the sight glass (I'm reluctant to go "all the way" to 0 bubbles since I don't want to overcharge), they don't seem to be getting worse (i.e., apparently there are no more bubbles than when I charged it).

Questions:

Is it possible or likely that the failure of the switch stressed the system and it leaks only under the very high pressure of when the aux fan wasn't working and the system was stressed?

Is there any likely permanent damage that may occur with the high pressures associated with the aux fan not coming on? Which components would be likely to fail (please, tell me that it's not the evaporator...)

Is there any reasonable workaround for the red switch short of replacing it? If I can't identify a leak that would require evacuating the system, I really don't want to do so to replace that stupid part (I'd have to go to a shop to have it reclaimed, etc.) Thoughts might be to use the old style/earlier model temp switch (vs the current pressure switch) affixed somehow to the condenser, etc.

Is it a bad idea to just jump the aux fan so it runs all the time? Will that shorten it's life significantly? I'm not sure how much they run in "normal" use - i.e., 20%, 50%, 80%... Winter is approaching (our temps are already in the 60s and will average 50 for the next 5 mos or so...) but we leave the AC on to reduce condensation as well as to keep all the seals lubricated. Maybe there's a way to switch the aux fan off the kilma so it runs 100% the time that the AC is on but not otherwise unless called for by the coolent temp switch...

Thanks in advance!

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Chris_87_300D
1987 300D - 415,000+ miles
1999 E320 - 220,000+ miles
2008 SL55
2019 Sprinter Diesel 4x4