Several questions on AC

Hi all,

I'm new to this forum. I'm very impressed so far with the Q & A. Here are my questions and forgive me if the questions may sound silly because I'm not familiar with how it works.

Background info. The AC unit was from original build back in 10/1996 and I'm the orginal owner. We never open the windows, so the house is always conditioned with either cold or hot air. The system consists of gas pump with the unit in atic and compressor outside the house. The system was never has any problems and I do change filters every 2 months. Over the years, I noticed several things:

1. The house seems to always have excessive amount of dust. We didn't do much about it because we attributed to cat's (we have 2) hair for the most part. Recently, we changed from carpet to wood floor, now the dust really shows up. If we don't dust or vaccum for 2 weeks or so, it will show up on all surfaces. Does this mean we need to clean the air ducts?

2. During summer time, we set the AC to 80 degrees, and like the pass few days where temp reach 100+ during the day, the unit doesn't seem to be able to bring the temp to 80. It would after maybe 6 or 7 pm, therefore the unit is always running. There's cool air coming fom the ducts but not freezing COLD. What seems to be the problem here?

Thanks in advance for any suggestions.

1. It could be that you need your ducts cleaned but, be sure to utilize a company that does it properly. There are quiet a few that don't know what their doing and can actually make the problem worse. Make sure that your duct seams are sealed up tight. Make sure you use a quality pleated filter. You may want to step up to an electronic air cleaner.
2. Here in Mi we went from mid 60 degree weather to mid-upper 90's in a matter of a day. No time to acclimate. Make sure your condensor coils are clean and this will help the unit perform at maximum capacity. Make sure your evaporator coils are clean this too is crucial to maximum performance. Having your evap coils in the attic doesn't help with tempature or dust. The dust may have clogged your evap coils and your not getting maximum flow across them. Lastly, make sure your freon level is correct, it can go low over time indicating a leak in the system. If you have guages, you can do this yourself, otherwise you'll need a contractor to check it for you but, this is the last resort. I hope the preventive maintenance tips will get you back to normal but, try those first, gas last.

I just noticed one of the compressor unit outside (I have 2 story house, 2 separate compressors), the cold line is not cold or "sweating" like the other unit. What will that likely to be?

Unfortunately, there are multiple causes for this condition ranging from low freon (indicating a leak), clogged dryer/filter, restricted air flow through condensor coils and/or clogged capillary tubes. You will HVAC manifold guages to check and interpret these conditions. You may have to call a service tech to sort it out for you.