I purchased a new air conditioner from this company 2 years ago when our old one finally died of old age. The new conditioner was installed late in the season, and seemed to work fine. Come the next summer, it wasn't working well -- when they came out to service it, they found there was not enough coolant in it to do its job properly, so they refilled it and it worked fine that season. A regular furnace maintenance this spring showed no problems, and everything looked fine for this year. Again, when it was turned on in the hot weather, it did not do its job; a check showed that it had no coolant. When I contacted them again this year, they were very helpful. They completely understood my frustration at having an air conditioner that was't working well, and did everything they could to get to the bottom of what was causing this recurring problem. After a lengthy visit to examine and test the unit, the company decided that there might be a leak in or near the compressor, and advised me they would replace the unit under warrantee. The dealer that provided the unit to them originally wanted to only provide a new compressor; but Mackenzie felt it best to replace the entire unit. All staff were very helpful to me and thoroughly explained why it took so long to get a replacement; and once they went in person to explain; installed and got the new unit up and running. Given that it took the company three visits to my home, and several phone calls to resolve this situation, I feel they were extremely helpful and pleasant. I am very satisfied with the service I received. In terms of service provided, it is in my estimation, excellent.