Air Temp was a referral and very happy I called them. The technician found where there was no where on my system /pipes could be blown out from inside out. He cut the pvc pipes and added, what I call a valve, where he could put the nozzle of the nitrogen can and blow the pipes out. Found my pipes have an extreme amount of sludge due to this never being done. Have rescheduled to have the pipes blown out again. I bought my townhome a year ago and had the original company come out to do a PM, and I knew from the time the 2-men walked in that I never should have them in my home. They were the ones that put my system in and never put a valve in to blow out the pipes, so 3- Years this was never done. The Air Temp Technician was Courteous, professional, knowledgeable and very helpful answering all of my concerns. I would highly recommend this company!