I am taking your advice and going to do the HVAC on my own. I've had 2 authorized dealers take a look so far. Will have 2 more. I've gotten one proposal back and the second guy will do one but his will be time-consuming and I hesitate to have him put a lot of work into the proposal when I'm still interviewing others. He said he would not be happy if he didn't get the job. I can't promise he'd be the one. NOTE: No load calculations were ever done on this house for heat or AC. I just learned this yesterday - 1 year into the job. The second AC dealer wants to do load calculations but, as I said, we've come so far and have limitations. Would it be worth his time? The first proposal goes like this: Remove incorrect air handlers and install 2 Trane variable speed Hyperion AH 2 Trane 2-stage SL16i condensers install Honeywell control system - digital programmable with WIFI replace all flex ducts on 2nd floor (I believe they're 6 or 7") with new 10" round flex with larger difusers Install 2nd return in ceiling on 2nd floor, redo existing return ducts The total cost of all this is $14,650. He also proposed installing a secondary heat source. We have Viega radiant heat panels in the floors but there is some concern that it will be adequate given the level of quality of the HVAC work and a poor experience with the electrical sub. There are 4 options for supplementary heat proposed: 1. Hot water coils in the AHs: $3400 2. Electric heaters: $700 plus cost of running electric lines 3. Carrier Heat pump (would mean using carrier equipment, not Train) $2900on top of AH price 4. Carrier Infinity 20 greenspeed heat pump - $5400 on top of AH price I have no specific model numbers from him - I suppose he doesn't want me to be able to compare prosals directly. Any reactions?

Thanks for the wire color info. Somehow it's working now after I jumpered Rc to Y and confirmed AC works (blower fan even came on without having to jump to G). Given the jumper results, I concluded the thermostat must be broken. So I went out and bought a t-stat. Before installint the new one, I put the old one back just for giggles, and lo and behold, it's working now. Guess I have a spare t-stat now.

I would replace the cap. It sounds like a 4 microfarad (uf), 370 volt run capacitor. Does it have only two terminals and look something like the one linked below? To discharge it after the power is off, short the two terminals together using a piece of insulated wire or a plastic handled screwdriver you don't care about. Also, short each terminal to ground just to be sure. Time also discharges capacitors, usually pretty rapidly, but short it just to be sure, even if the power has been off awhile. Here is a link that might be useful: Is This It?

The ceiling above the crawlspace is the bottom of the first floor. The warm moist air in the crawl space will rise up into to house if there is no vapor barrier to stop it. I would expect a three year old house to have tight windows and doors. The crawl space might be a source of the excess moisture in the house. What size is the AC? I would think a 2.5 ton single stage, or 3 ton 2-stage AC would be sufficient for a newly constructed 1749 sq. foot single story house. Did the builder provide a load calculation? A 6-10 minute run time might be considered short cycling. How often does this happen in an hour and what is the outside temperature?