Responded to second opinion. Home is 1 year old. Customer is having comfortability issues upstairs. Currently 8 degree difference between upstairs and main level. Explained second levels commonly have comfort issues. Customer had concerns with unit sizing.. found 3.5t ac installed. Per customer home is 3000 sq ft. Advised unit slightly undersized. Also found 8x24 return duct. Advised also small for system, 10x24 or 12x24 would much better suit home and allow better airflow throughout home. Advised we can replaced 3.5 with 4 ton but concerns still present with total comfortability upstairs. Customer has eco bee with smart sensor. Explained use of sensor and it’s pros and cons of use. Advised mini split would be most guaranteed route for proper comfort. Left quote for 3 head multi zone system. Customer is to talk with significant other and contact us to proceed.