We have dual ac in a 2 story home.The upstairs is overly cool and downstairs is hot.AC tech says the damper is not working due to static pressure, and that this 10 plus year old home duct work is undersized and needs to be increased.really is this the deal 4k to replace.He says the t-stats are fightinf each other and the pressure won't allow damper to function.HELP already spent 5k on new unit 2 weeks after moving in last week.HELP

We have dual ac in a 2 story home.The upstairs is overly cool and downstairs is hot.AC tech says the damper is not working due to static pressure, and that this 10 plus year old home duct work is undersized and needs to be increased.really is this the deal 4k to replace.He says the t-stats are fightinf each other and the pressure wont allow damper to function.HELP already spent 5k on new unit 2 weeks after moving in last week.HELP

If you have a 2 story home and you have 2 A/C units it should be simple to have one unit cool the downstairs and the other unit to cool the upstairs. Now I have no idea of the design of your system but I have sold and installed many 2 ,3 and 4 unit systems in some of the finest homes around here and never had a problem.
Question?? Was the home originally designed to have 2 units or did someone just install 2 units lately? As a temporary cure take the motor off the damper and wedge it open to allow circulation at all times. This is a temporary cure but it will get you by until someone local on your end can make sense of it all.