Thank you all for you help! I had a repairman come out this morning. Said Unit 1 with the squealing is a bad compressor. $1500 for a new compressor. He recommends a whole new unit at $1995. Do those prices sound right? It is a 3 1/2 ton carrier ac unit.
Unit 2 was a bad capacitor! You were right! He wanted to charge me 220 to fix it. I said no. Found it online for under 30.