You won't get near as strong a vacuum with the Mighty. You really want some power to get that crap out of the A/C. I suspect a modified fridge pump will work. I'm looking for a cheap used a/c vacuum on greed bay.

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My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory