Follow the airflow path through the home
A Carmichael comfort complaint should identify which rooms receive weak airflow and whether the problem occurs in both heating and cooling. That pattern can help distinguish a distribution issue from a single operating-mode failure.
Before choosing a stronger filter or replacing a blower, check the filter size, return path and equipment requirements. Filter efficiency and airflow need to be considered together; a higher rating is not automatically suitable for the existing cabinet.
For rooftop units, bring airflow and filtration into the scope discussion. A failed component may justify repair; repeated faults or a major failure can justify a scoped replacement comparison. Include building interfaces and access costs so proposals cover more than the rooftop cabinet.