It's probably too cold. Remove the front louvered cover to expose the cap tube. The one from the stat. remove the rubber bumper from the front coil and pull the cap tube from the rubber. Hold the cap tube in your hand until you feel that the tube is pretty warm. then turn the unit on. How long does it run ? If the stat is a snap action one find yourself a portable heater with a fan, an old car warmer will do. Have it pointed to the area of the stat. Let it get good and warm. How long does it run ?

Check the bearings on blower unit, if the blower spins freely, you need some pro help, especially with no wiring diagram. Without seeing the setup it,s impossible to give more detailed advice.

" So, how can I get them to explain to me why they recommend a 110?" The contractors who did not do a load calculation will say it is based on the size of the house. This is wrong and leads to over sizing. The one contractor (Sears) who did a load calculation thinks the heating load should be doubled which is also wrong. It is hard to have a conversation about this with a contractor who has already predetermined what size should be installed. "Also, if I do go with the bigger furnace (110k BTU), what exactly am I compromising on? You say bigger is not better. So what exactly is wrong then?" Here is a list of problems caused by an over sized furnace: Short cycling: The furnace runs in short cycles. This constant on and off creates a lot of wear and tear on the furnace and leads to premature failure. It also creates a blast of air every time it turns on causing excessive noise and discomfort. High static pressure: A big furnace needs a lot of air. Your duct work is likely too small to handle the air flow and will cause a restriction. The restriction causes the furnace to run hotter which will overheat the heat exchanger. This will cause the heat exchanger to fail prematurely. This is a very expensive repair. The undersized duct work causing excessive noise. Lower efficiency: During the first 5 - 10 minutes of operation the furnace is operating at a lower efficiency. If it short cycles it does not reach its rated efficiency level. Less Comfort: The short bursts of air blowing at high speeds and the extra noise make the house less comfortable. This is the primary reason forced hot air systems had a bad reputation 20 years. Proper sizing and variable speed furnaces have greatly improved the comfort level. "So, I don't know why you are saying I don't need a 4 ton AC." You don't need a 4 ton AC because you said "Manual J came out to 3.28. " As Tigerdunes stated above you should get either a 3.5 ton single stage or a 4 ton 2-stage condenser. If I knew the city where you lived, and the summer design temperatures used in the calculation, I might be inclined to round down to 3 tons if you lived in an area that suffers from high humidity. I don't know what temperature you set your thermostat to, but I am comfortable at 78 degrees at 40% humidity. I find it more comfortable than 75 degrees at 60% humidity.

Extremely unlikely because as the guy said... eventually the unit starts and runs fine. Voltage drop = no run. "If voltage drop occurred while unit was running... it would not stay running." No where does OP say anything about unit cutting out while after starting and running. You have to know what you are talking about to come to such conclusions. LOL. Does a car keep running if there is no gas? Can a car be hard to start, but then run fine once started? Yeah ok, common sense. While a car is a poor comparison more people understand the operation of a car than anything else I could use as an example. voltage drops tend to stay, not magically disappear and reappear. But thanks for playing.... In over 22 years of diagnosing only 1 voltage drop problem... if you have a voltage drop you will know it quite easily. (More complex problems in regards to start up? Uh no. Guess again and again and again.) More common to drop a leg from the pole... while also rare that's happened about half dozen times in 22 years of running service. Central AC Unit won't start with only 120v available, that confuses people because some things inside the house will still operate normally as long as it doesn't require the full 240v to operate. In Vegas, they give you odds... in a forum board that's also what I give. Magic 8 ball --- out.