My heating unit went out on the upstairs unit. Windy City Air Conditioning & Heating was able to respond the same day that I called them. Their customer service is absolutely excellent! The technicians that came were very thorough and communicated every detail with us. They gave us options for repairing the system and I felt like they were very honest and upfront. They did fix the heating unit that same day and it has run great since. For this to be a first-time visit they did an excellent job and I would recommend them.