This unit can barely provide air conditioning

My landlord told me not to call him with HVAC issues when I first moved in. He said that he had a HVAC contractor clean and care for everything. The landlord obviously lied and did not want to deal with paying for a HVAC repair. I know he lied because the washable air filter in the system was disgusting when I moved in. There was tons of dust and dog hair in it. The whole inside of the HVAC had big gobs of dirt in it too. After cleaning it, the HVAC worked better, but not great. The HVAC unit works by either doing heating or cooling. There is a toggle on the thermostat that is pushed to either heating or cooling. If I have the AC on accidentally and it is winter, I will get cooling. If the toggle is on heating and it is a hot summer day, I get heating. I always have to pick what I want, heating or cooling. There is no set a temperature and let the HVAC figure out what to do. I hate deciding when to move to heating or cooling. I don’t think the system is very good at the air conditioning function either. I barely notice when the cooling is on. For very hot days, the thermostat can be set super low, and the AC just can’t keep up. I use the ceiling fans with the AC and the house is still hot. I think the landlord knows something is wrong with the cooling function and did not want me to call him about it.

furnace installation