I ditto SummerBreezeNY: This is a common problem in apartment buildings. You can't expect your upstairs neighbor to move their unit because it drips. All A/C units are going to drip. What about when it rains outside? You are going to get a lot of "tinks". You could move your unit, but when it rains, you'll hear it, too. Both our AC units make noise when it rains, but we don't have anyone dripping from above. We took a nylon rag rug, folded it over to be the same size as the top of the AC unit, laid it on top, and wrapped a bungee cord around it. We used nylon, because it doesn't rot. It lasted us a long time. We also once used a vinyl doormat w/ a fiber top. Bed Bath & Beyond last year carried a foam pad specifically for the top of the AC unit; I think it had a magnetic bottom, so it stayed in place.

Open the grill by releasing the two latches (pull them down, they're attached to the edge of the grill and don't come off). The grill is hinged at the other end and should there hang open. If you want to remove it completely to clean and/or paint it, it should unhook at the hinges. The filter simply fits up inside the frame. Swing the grill up/closed and reset the latches. If there's no filter, then whoever was there previous to you either ran the system without a filter, or removed it before they left. If run for a period of time without a filter, the evaporator (cooling) coil up in the blower unit may be clogged. In some oddball cases there may be a(nother) filter up inside the blower unit ... which if so, that may explain why (if) there's no filter at the grill. But the point of having the filter at the grill is for ease of access to change it without going into the blower unit.

A lot of problems with air conditioning are caused by dirt. Dirty outside coil can cause the head pressure to go high. On a hot day the Freon can burst a hole in the system, cause a compressor to fail, cause an electrical breaker to trip then fail. Keep the outside coils as clean as possible. Keep plants from growing against the finned area, keep the exhaust pathway free of obstructions. The inside coil is another story. A dirty inside coil can cause the coil to Ice over and the flow of air is reduced. When this happens the ice gets thicker and the air eventually stops completely. The major cause of dirty inside coils is not changing the filter often enough. To clean an inside coil is a dirty time consuming job. I have heard of cleaning jobs that cost more than the labor for new installation of equipment. Even for the most diligent customer, the coils will need cleaning occasionally. In my home for example, we cleaned the coils after 15 years. The coils were dirty. I re-examined them 7 years later and they were clean. The system is 33 years old now and I should probably examine the coils again, even though I am careful to change the filters on a regular schedule.

i just had central AC installed in our 20 year old MH. the contractor put a pvc drain tube thru the floor near the coil which is fine, but i am wondering if the small puddle (5" in circumference) of drain water i see on the ground under the home could become stagnant and become a mold issue?? our soil is very sandy fortunately, but with all of the skirting blocking off airflow, i figured i better ask. thanks for any input! :-)