Hot Upstairs I bought a new house 4 yrs ago and during the first summer I noticed that I could never get the upstairs cool. The best I get is 80oF My master bedroom is downstairs and very cool so being hot upstairs wasn't a big issue until now. Now my kids are ready to move into their rooms upstairs and I am wondering what I can do to cool these 3 rooms and a gameroom. No window unit AC is permitted in my subdivision. Every room has a vent but these vents are not big enough to produce enough cool air to neutralize the heat. What are my options? Can an HVAC guy increase the size of the lines or duct and put in bigger vents?

Upstairs is usually for winter heating where downstairs is usually for summer cooling.

if there is no control of air movement between floors and you have it on cooling then any cold air will go down to the lower floor
or alternately if you have it set on heating all the hot air will rise to the upper floor
where is the system located (upstairs or down stairs ) and where is the thermostat located
to get control close any upstairs to down stairs doors or erect a heavy curtain across the stair well

You need to have someone evaluate the ductwork for the home. With all zones calling, there should be an even balance of airflow. And when only one zone is calling, there should not be the tornado effect you describe.

The dampers feeding each zone may be of the wrong size. It also sounds as though you are also having a problem with your bypass damper. This damper is designed to bypass excess air when only one zone is calling. It is operated typically off the airflow alone.

Have it check out. You definitely have a problem. I would recommend getting it looked at by a company other than the installing company to remove any bias judgment or diagnosis.

I'm assuming you have had a competent Air Conditioning contractor look your unit over.if you trust your A/C contractor, why don't you work with them towards an answer? I would get an air flow and sizing analysis, a full equipment service/performance check, and see if there is something simple causing this dilemma. Possibly low refrigerant charge,or you have a filter or coil restriction on the indoor unit. I've seen mold plug a coil solidly before. And due to new federal regulations on air conditioning efficiency and the phase-out of R-22, I would recommend that any replacement equipment be done in full, not part and parcel. The newer two stage energy star rated cooling and/or heat pump offerings are a fantastic solution for premium indoor comfort, and the government is offering powerful incentives right now if you're in the market.

i had a similar problem, and a six inch duct and inline booster fan didnt help, the room was just to far away from the furnace and ac. to save energy, i use an oil rad in the winter, and a portable ac in the summer, it works great.my house is a back split, so its a common problem. in the summer, all downstairs dampers should be closed to push the cold air upstairs ,as it will come back down anyway and the basement is cooler as it is. so if you have 4 flores, you close the bottom 2. bungalow you close the basement

If you are referring to the secondary pan there could be a problem with your drain line.i would find the drain at the exterior of your home and **** it out with a wet vac..most A.H.Us have float switches or moisture sensors.They will shut down the unit if the drain clogs.

is the system zoned? if so maybe the zoning control board to the damper motor is wired improperly. when a system freezez its because of 1- restricted air flow across coil, (maybe dirty filter) or 2-low refrigerant charge. again could depend on how its zoned.

Some of this depends on where the air handler/furnace is located. Most often in two story houses, it's in the attic upstairs, or in a closet upstairs. A duct routes air from the furnace to the downstairs supply duct, so it is a distance from the air handler.
When the unit first initiates a heating cycle, that duct is going to be full of cool air, and the duct itself will be cool. So the furnace has to run long enough to push the cool air out, as well as warm the duct up, before your going to feel warm air at the registers downstairs.

Keep in mind, heat rises. And, your thermostat only monitors the immediate area where it's located. In your case, upstairs.
Two story houses are problematic because of this. And one way around it is to have a damper system installed that distributes the air upstairs or downstairs based on a thermostat located in those spaces. There would be 2 dampers, and 2 thermostats (one upstairs, one downstairs). Each stat would control a damper, and the call for heat or cooling.

Let me know if you would like to consider a system like this, and I can point you to components to use. I've put several system like this in.

It sounds like a restriction in your ducting. Feel the A/C vents in the hot rooms to see if cold air is blowing out of them. If the ducts are restricted, then it is possible that the air conditioning coils are freezing up from lack of circulation. Inspect the ducts if you can to see if there is any restriction.

Note that even if you feel air coming out of the ducts, it could be ambient as opposed to cold. The best thing is to measure the air temperature coming out of the ducts. It should be around 20 degrees colder than the ambient air at the intake of the A/C.