Filters, Filters, Filters. No question. It’s not even close. Dirty filters are the number one preventable cause of service calls to our customer’s homes and offices. Dirty filters can cause a myriad of A/C problems ranging from frozen coils to damaged compressors. Please change your filters. Call us if you are unsure what type of filter is best for your home, or you don’t know how often to change them. We are here to help. And in case you are wondering about the second most common preventable cause of service calls to our customer’s homes and offices, it is batteries in the thermostats. You should change them every couple of years.