I have a Goodman unit that went out. I had to get it fixed. The failed heat exchangers caused the circuit board, transformer, rollout switch and some wiring to fry. Although the heat exchanger was a warranty part, the only warrantied part, the company who replaced the heat exchanger charged $450 to replace the heat exchanger. Other costs were: Smart valve system control board - 271.00, rollout switch - 55.00, transformer - 68.00, trip charge - 60.00.