The largest threat to the AC unit that could cause a service call for ac repair throughout the fall and winter months is from tree branches and other debris. Dirt and dust are not wonderful either, but falling debris is the main factor to protect the AC condenser from.
Falling debris blended with water from rain makes a dense sludge which could very easily clog drain holes in an HVAC system. Components are built to be able to drain water, but include the sludge and soon it can not be able to drain. As water accumulates within the condenser unit, it will damage the electrical components, result in rusting, and in short order lead to unnecessary AC repair.
We have seen homeowners who made their own covers for the outside HVAC system out of plywood, tarps, and a lot of other materials. While they may be a good temporary fix, all usually will not provide for the correct quantity of air flow needed. If the AC unit was to run and insufficient air can enter the system, it is going to work much more difficult than needed and may burn up the parts over time.
The ideal thing property owners can do is purchase an air conditioning cover created for ones AC unit. Buying the right cover will allow for the ventilation of air which will be required for the cooling system. Most HVAC manufacturers build covers that will work. Contact us for AC repair if you need assistance getting the appropriate one for your system. They usually do not cost a lot of money and are easy to put on oneself. If you would like us to setup the cover we will give the unit a fine cleaning initially, to be sure their is no sludge build-up already.
Some AC covers are designed to never have to be removed, and are UV-resistant and will last probably as long as the HVAC system does too.