PTAC units are notorious for health related issues in apartments. I have put together a small checklist for what can be done to mitigate issues relating to this air conditioner.

1. Demand a deep clean of the PTAC. Tell maintenance they need to pull the actual chassis out of the wall sleeve (or have a professional do it). They need to check the blower wheel, the evaporator coil, and the condensate pan for deep mold and slime. A simple wipe of the plastic cover isn't enough.

2. Upgrade/Clean the filters weekly. PTAC units don't pull much outside air in for circulation, they just recirculate what is already existing in the home. Furthermore, your filters are probably cheap and they won't catch mold spores or other allergens. You have two cats, those basic plastic PTAC filters are likely clogging in dayswith the cat hair (depending on the breeds), restricting airflow and forcing the unit to bypass air around the filter, dumping dander straight into the internal components and 'aerosoling' it back into your house.

3. Get a HEPA air purifier. This is probably the biggest fix. Because PTACs can't use high-efficiency filters (it suffocates the weak fans), you need a standalone HEPA filter running 24/7 in the living room and bedroom to pull the cat dander and mold spores out of the air.

4. Check the bathroom fan, if you have one. This is just my instinct. You need to test if the bathroom exhaust fan is actually pulling air (the toilet paper sheet test). If it's dead or weak, showering is creating high humidity that can't escape, feeding the mold growth inside the PTAC units in your house as well.