4 years ago we bought a brand new Carrier system from Climatic for the upstairs unit after the builder Goodman unit died. About 3 weeks ago we noticed hot air coming out of the vents so I called up Climatic. After the initial $200 visit, which was for cleaning out the rust inhibitor which our system does not have, I'm told the 4 year old coil is bad and needs to be replaced for $830. So, I apparently need another $830 on top of the $200 already spent in repairs for labor to replace the coil. I decided to wait as the weather at the time was in the low 80's and see how the unit does when the heat gets really bad. It was keeping up fine during that time. Over the last week, for testing, I have kept both AC units set to 72 degrees in the house. The main unit (goodman) has easily maintained the 72 degrees on the main floor and basement. The upstairs unit has struggled and ran constantly for the last week but has been able to keep the upper floor around 76 degrees. Over the past week that is around a 20 degree spread. The diagnostics the tech did says my unit is not functioning properly due to the coil but I have been told that these new units only guarantee a 20 degree spread. Is that true? If the 20 degree spread is the case then I think the unit is working about as good as it should. That's not to say I don't expect better. My point of reference is the Goodman unit we had for 12 years. It cooled the upstairs better when it was working properly. A potential $1000 repair for a 4 year old system is disappointing to say the least. Beware if you buy from Climatic that the warranty (at least 4 years ago) was only 1 year labor 5 years parts. It should be 10 on the parts according to Carrier's website but I have not been able to confirm that either way thru Climatic. Note that 1 year labor is the bare minimum Carrier requires for all install partners. I would negotiate that if you can if you have to replace a unit. My father just had a new American Standard unit installed with 5 years parts and labor from a different installer. When my big unit dies the labor warranty will be my number 1 question and I will not be going with Carrier again. This unit has been disappointing all around.