[jaelmark]

I have a problem. I just installed a new 12 SEER Grandair 3 ton unit in my house. I have a zone system which has a thermostat in the main floor, and another thermostat in the upstairs bonus room. I have the main level thermostat set on cool at 73 degrees. I have the upstairs thermostat set at 76 degrees. The system freezes up completely. I know it is an air flow problem. I suggested to take out the doors from the zone system and have only one thermostat control the whole house to keep the unit from freezing up. Do you have a better suggestion?? ---HELP---

[tk03]

You are sure it is an airflow problem? How. What about a charge problem?

[jaelmark]

It's not a charge problem because I put the cages and the charge is good...

[jaelmark]

I am saying airflow problem because there are only 4 air vents upstairs on at one time. On the main floor there is 10 air vents...

[TristaNicholle]

Was there a bypass damper installed in the basement? Or is your ductwork sized big enough to run one floor at a time?

[Joshdta]

How many returns are on each floor?

[jaelmark]

There are 10 returns on the main floor, and 4 on the second floor.

[jaelmark]

Yes there is a damper.

[Joshdta]

So you have 14 returns and 14 supplys? What size is your duct downstairs? And do you have a bypass damper between the supply and return?

[jaelmark]

The Duct for the downstairs is larger than the duct that feeds the upstairs. Do not have the exact measurement. No there is no bypass between the 2 ducts under the house.