AC Unit is in a Mattmay Home new construction - Installed by Del-Air, brand new Carrier system on 04/2010 with "custom sized" only air-filter??!!. Closed on the house 06/2010. System warranted for one year parts and labor, 2 year parts and labor with Mattamy extended warranty, 5 years parts only. Within the first year the system backed up and the drain pipes were clogged near the drain exit. Drain pipe installed incorrectly which caused back up - bully Del-Air service tech. (who was artificially polite) tried to charge me over $500 to clear the line and fix the incorrectly installed drain line stating that I failed to do the "required" six month maintenance. I had to ask him to leave my house, call the builder to enforce the warranty, while he waited outside my door for over an hour! Religiously poured vinegar down the drain line every month and did yearly Del-Air maintenance on the system. 06/02/2012 - Yearly maintenance performed $79.95 05/12/2013 - Yearly maintenance performed $79.95 08/28/2013 - AC shut-off, overflow, very hot, rust from evaporator blocked drain hole, I removed 2" shards of rust from the unit, unit turns back on, call Del-Air to check the system and evaluate rust problem. Del-Air flushes rust from drain line, flush fills overflow tray with water, does not clean up after service, fingerprints and dirt on wall and trim, takes me 20 minutes to soak up the water with an automotive sponge and fill a bucket with the water! Again - the service tech is "artificially polite." I asked how could the lines clog when I just had service performed, tech told me to call office, charged me $79.95. Manager gives me a credit of $39. Tells me rust is normal and Carrier will not warranty the evaporator part until it actually bursts!! 09/12/2013 - AC shut-off, no fan, blower motor failed. Del-Air - part under warranty - $79 diagnostic fee, $208 labor. Refuses to apply $39 credit to diagnostic fee, artificially polite tech., replaces blower in under 10 minutes!! He wasted more time in his van calling his supervisor before, during, and after the blower replacement. (Filling the time by wasting it and charging me way too much!!). Mattamy is repairing an unrelated leak on an exterior wall, installed a huge heat pumping De-humidifyer in my living room, asked Del-Air tech if this could have caused the fan motor to overwork and burn out - he tells me, "Mattamy is a huge client of our's, and does millions of dollars of business with us every year, I will not make any statements that would jeopardize our relationship with them." I had to threaten not to pay if he did not make an honest note in his report that the added heat from De-humidifier caused the fan blower to work harder. In four months I have spent $450 on a three year old Carrier AC unit installed and maintained by Del-Air. I am not sure who I am more disappointed with Carrier or Del-Air.