Comfort-Air has been servicing (and replacing one entire unit) over the past fifteen plus years. Every field technician has had the knowledge to diagnose any problem and has always fixed that issue so that there were no 'call backs' because something was not quite right. Even the office personnel have always been very helpful, from the receptionist to the scheduler, and those that I had to leave a message for would return that phone call promptly. Very, very competent company and have recommended them many times for both residential and commercial projects.