Lennox Air review: HVAC system

We purchased a newly built home 4 years ago. We have 3 Lennox units. we have had problems with one of them since the beginning. We have paid over $4000.00 to repair that unit. We replaced the evaporator coil, which was covered under warranty except for the labor. We also had to replace the condenser coil and mother board which was not covered at all.
This past week we had to totally replace the other 2 units for the same reason. We paid $20, 000.00 to replace 2 Lennox units that were 5 years and 3 months old. The parts to repair them aren't available so we had no choice. We may have to replace the third one eventually. The 5 year warranty didn't cover the units because it started when the builder purchased them. So we had 3 and half years of warranty for brand new equipment. Lennox was aware of these defects when they manufactured our units and still put them into the market. Looks like a new lawsuit is in order. What happened to accountability in America.