Delta Mechanical installed an air conditioner just less than 5 years ago. This week, it stopped working and I have left several messages with their office person to try to get someone out to check on it. NO ONE has called back, so I had to call a local company. After all, it's hot here in Tucson and my health is at risk without my air conditioner. Luckily, D & H responded the same day and are working to get the work done before it falls out of warranty. I am thinking Delta does not want to deal with the warranty issue. I would not recommend anyone use this company in the future.