Air Conditioning - Central air problem PLEASE HELP

My house doesnt seem to cool properly. I checked the air coming out of my vents and it is blowing out 50 degree air however my unit seems to run all the time. I also checked the air around my thermostat and it was the same as what the thermostat said. I am a new homeowner and am unfamiliar with all this stuff but I know my house should get cooler than it is. Could my blower on my furnace be running too low and not blowing enough air? Anyone have any advice?

What year is this home? Is it well insulated? Has the filter been changed? How old and what is the make of this A/C system?

The house was built in the 50's. I am not sure about insulation. some of the walls seem to be cold in the winter. I have a reusable filter and it is clean. I am not sure on how old the a/c unit is but the furnace is new.

In the hottest weather the A/C should run continuously. It needs to do so in order to lower the inside humidity.

Assuming that you are not experiencing a streak of extra hot weather there are several possibilities.

It is possible that the blower is running too slow. It should be running at a higher speed than when heating.

If the cooling was added after the house was built then it may very well have been inadequate from day one. Ductwork that serves both heating and cooling is always a compromise and if cooling was added to a system designed originally for heating only then you will have less-than-stellar performance on cooling.

Discharge air at 50 degrees is not out of reason. It is normal for the differential between the return and supply to be about 20 degrees. If your home is about 70 degrees then the 50 degree supply would be correct. If it is blowing 50 degree air and the house is 85 then you definitely need to move more air past the cooling coil.

If your system is properly sized but you allowed the house to get to a high temperature before starting the A/C then it will take a long time to get the temperature down.

Are you gone during the day and leaving the A/C off or set to a much higher temperature? If so then try leaving the thermostat at the desired temperature for several days and see if it gets better.

I have a reusable filter and it is clean. This is where Id start first. They are no good at all. Get like a MERV 5 filter .Not over . Id check and make sure the AC coil is clean there. Check the big copper pipe at the unit outside it should be cold and wet . The small copper pipe warm to hot. If not you could need freon

The outside temp today was around 90 degrees and i had my thermo set at 70. So maybe it is normal to run all the time. If it was the fan speed how would i speed it up to try it out? iI do leave the thermostat at the same temp throughout the day as well i do not change it. also about the filter i have an eltronic air cleaner which is where the filter is. can you use disposable ones in those kind of machines?

Electronic air cleaners (filters) use a high voltage to cause dust particles to adhere on the plates of the collector cell. They are very good at collecting very small particles of dust and can even remove smoke from the air. They are not so good at collecting large particles of dirt and they need to be cleaned about every two weeks. If you don't clean them this often they tend to not collect anything.

The electronic air cleaners also have a VERY coarse filter, similar to the grease filter on a range hood, to stop large pieces of dirt from getting to the electronic collecter cell. This pre-filter is almost useless for anything other than very large particles.

Most HVAC service people do not like electronic air cleaners because most people simply do not clean them often enough.

The collecter cells are usually of a size that a media filter may be substituted for the electronic cells. Obviously when this is done the power to the electronic air cleaner is turned off and left off.

I like my electronic air cleaner but I clean mine every two weeks. A media filter may last as long as three months before needing to be changed. Unlike an electronic cleaner the dirtier a media filter gets (within reason) the better it is for catching dirt.



It is possible that enough dirt and dust has gotten past your electronic cleaner that it has deposited on the cooling coil and is seriously impeding the airflow through the coil. You need to ascertain that the cooling coil is clean before thinking about increasing the air flow by speeding up the blower. There is also the possibility that your system is low on refrigerant and causing the cooling coil to ice up, that is, for the condensed water (from lowering the relative humidity) to freeze on the coil and that will impede the air flow.

Im not sure im following you. The air cleaner is inside my house and my a/c unit is outside, arent the coils on the inside of my a/c unit? And i did notice today that my copper line that goes into my house was iced over.

I had a simalar problem with my AC last year. Air that was blowing out was cold, but just not blowing very much air. I turned out that my filter was dirty and it had caused my a-coil to freeze over and the lines comming into the house from the AC unit. I turned the AC unit off and just ran the fan on the furnace until it thawed out. It took about 3 hours and it was up and working great again.

Hope this helps.

Neilsarah, the A/C is comprised of two units. The "outside" unit is properly called the condensing unit and the inside unit is the evaporator coil. They are connected by two copper tubes. The smaller copper tube is called the liquid line and the larger copper tube is called the suction line.

The way it works is just like your refrigerator. By means of pressurizing and cooling a gas (the refrigerant) it becomes a liquid (condenses). That liquid is then expanded in the evaporator and the heat that you wish to move, either from inside the refrigerator or inside your house, causes the expanding liquid to change to a gas. The heated gas then returns to the condensor where it is compressed, the heat removed and the cycle starts over.

The evaporator in your A/C is located in your furnace ductwork and the blower in your furnace causes the hot (and moist) air in the house to flow over the evaporator. The evaporator is made of of a coil of tubing with fins attached that has fairly small areas for the air to flow. These passages can, and will, fill with dust to the point that it seriously impedes the airflow. The filter is to catch the dust and dirt before it can collect upon the evaporator.

If you have not been scrupulous in keeping the electronic air cleaner clean a fair amoount of dust and dirt has traveled past the cleaner and has become embedded on the evaporator. This is the most likely cause for decreased airflow.

A second problem with decreased airflow through the evaporator is that the evaporator will now cool to below the freezing point of the water that it is removing from the house's air. This water will then freeze on the evaporator and further choke the airflow.

Furd. Thanks so much for all your help. I pulled my cover off and looked at my evaporator. Looking at the very top of the fins i do see a fair amount of build up. What is the best way to clean this off. Also I see a small tray at the bottom of the coils that has water in it. Is this normal? I am assuming that it was frozen when it was running earlier and the water is from that but I am not sure. Thanks again for all your help. also is there anywhere below this unit to clean or is this it?

My expertise is in commercial and industrial sized equipment, not residential so I hope one of the residential experts will add comments.

Probably the best tool you can use for the cleaning is the small round brush for your vacuum cleaner. Be careful not to bend any of the fins.

The pan is where the condensed moisture from the air falls as a function of dehumidification. It has a drain pipe (or tube) on it that drains to either a floor drain near the furnace or to a condensate pump assembly that pumps the water outside or to another safe drainage place. It is not abnormal for there to be a little (less than 1/4 inch) of water in it but you should check to see that the drain piping is clear and if you have a condensate pump that it works okay.

Thanks for all the help furd. I have a yellow lab and it seems that his hair acted as a filter. It was like a 1/16 of an inch blanket of dirt and hair on the lower side of all the fins. Hopefully that was my problem. I am running it now for a test. One last question about my air cleaner. I am definitly going to buy a new one cause the corner of mine is ripped, but the fins that are past this filter dont seem to be dirty. Do I clean these also. If so How often. Are these what you were refering to as collecting small particles? Thanks again for the help.

Might look into a Air Bear 4" filter. To fit into where the EAC is now. Like said if you dont wash the elements every two weeks you have no filter. They make what is called a fin comb. That you can get to help clean the coil ;)

I know well about Lab (and Golden Retriever) hair. I have one of each & have to do my filters at least every two weeks & should each week.

Ed mentioned the Air Bear 4" filters. They are a very good filter & usually come in sizes to directly replace the your electronic filter greatly reducing labor costs.

I think that Ed and Grady are giving you good advice concerning your filter.

Could some one tell me what tool is available to check on the A/C to see if it is working properly. I have seen the repair guy pointing something against the vents. It appeared to be some sort of infra red device. He also mentioned something about air pressure. Is this something which I can buy from homedepot? If so, what is that I should be looking for?

The problem I have is similar to the one listed in previous thread. The A/C is running overtime but it is not cooling the rooms. Today the emergency maintenance guys came and shut off the unit so that the ice around the filter and coils can melt. Finally they turned on the machine and left for the day. I am unhappy as I find that even after running continously for 2 hours the temperature inside the house has not dropped to my thermostat setting.

Couple of months back they charged the unit(replaced freon). So I am thinking maybe there is something else broken. Please help..!

newbee_13 If your coil is clean the air filter clean. The big copper pipe should be cold and wet. the small copper pipe warm to hot. At the out door unit. sounds like you have a good leak the should be fixed. Any ice means no air or low on freon Most of the time

Newbee, unless your A/C is vastly oversize for your home it is doubtful that it can lower the temperature much faster than two to four degrees an hour. If you allow your home to heat up well past the desired temperature before starting the A/C it will be playing catch up and quite possibly never reach the desired temperature until well after the outside temperature has dropped significantly.

Do not turn off (or significantly raise the thermostat set point) when leaving the house.

My evaporato is iced up, I found out by taking the side cover off, I then saw a huge block of ice.. I shut down the condenser unit but left the blower on. I took the V cover off and I did not seee any dirt in the fins, however my evaporator still ices up, It just recently started doing this out of the blue. I used to work on cars, and the way it used to work was, that when the compressor had to kick on to circulate the refrigerant it kicked on, but then it shuts off automatically, is there no such swith on the condenser outside..? should it not know not to keep circulating the refrigerant..?

I'm puzzled on what to do next...

Thank you.

Most residential equipment does not have low pressure switches. Check all of your registers (supply & return) to make sure they are open & not blocked. If all is well there, it's time to call a tech.