It's pretty simple. AC units need to be cleaned and serviced on an regular basis. A simple cleaning of your condenser coil will go a long way to prolonging the life of your unit. You must clean your unit from the inside out. While your in there you should also take your shop vac and remove any leaf, or buds that may be in the unit. Last summer I went to a friends house and discovered his 10 year old unit had never been serviced and was done.
Cost to replace $4000/$5000.
Best to clean inside out for sure but can also rinse the exterior and use a coil cleaner.
Similar process for heat pumps but make sure to rinse after as they won't sell rinse like AC coil indoor will.
https://www.canadiantire.ca/en/pdp/ac-safe-heavy-duty-air-conditioning-ac-coil-foaming-cleaner-19-oz-0438291p.0438291.html?utm_content=shopping&gclsrc=aw.ds&ds_rl=1283573&gad_source=1&gad_campaignid=1530457094&gbraid=0AAAAADojZpgIZCvQh_M7m9rlt9KSwHR3R&gclid=CjwKCAjwwL_UBhAjEiwAEhuT5KXK3wSOjz7y-85dZSNWCNTWhbvVCmwJyMKCCPygYmbFosVph1-h9xoCZ98QAvD_BwE#store=447
It smells a bit but not too bad
I have a screen cover for my HP, works great to keep the leaves and junk out but it still needs maintenance. Good snow, ice, etc as well.