Air Conditioning - not cooling

Have an older Carrier ac model no.XCA63D serial no.1493B56626 that comes on,runs good,but does not cool.I can hear the compressor come on,but the unit never cools below about 65 to 70 degrees,it's just an expensive running fan.What do you guys think might be wrong?Out of freon?

Is it the air coming off the registers that never cools below 65-70F?

Or is it the temperature inside the house that does not go below 65-70?

If it is the house, you have too high exectations...a central A.C. system is expected to keep your indoors at 75F and is sized accordingly.

If, on the other hand, it is the air coming off the registers that you're talking about, then you have a problem. Air off the registers is expected to be somewhere between 55-60F

Sorry,I did not say,but this is a window unit and the temperature that I,m taking about is right out of the discharge vents on the front of the unit.

The problem is then, very likely, one of an "out-of-calibration" thermostat.

The thermostat is the control behind that dial that has numbers on it...say, from 1-to-8, or 1-to-10, or whichever may be the case with your window unit.

When they are new, these thermostats click (and turn the compressor ON) as soon as you start spinning the dial away from the "1", so if you turn the dial to 5, or 6 you'll get plenty of cooling...but as they get older, their sensitivity drops and you may have to spin the dial close to the highest number, and this causes the compressor not to stay ON long enough, and won't cool off your room.

Some window unit thermostats are recalibratable, but most are not. You would actually have to remove the front cover and the control plate, unscrew and remove the thermostat and see if it is recalibratable. If it has a little hole at the bottom of which you'd see the head of a flat screw, with a small screwdriver spin this screw on the direction that says "colder", which is engraved on the thermostat itself.

I can hear the compressor come on,and it stays on,but the unit is not cooling,and now after running for about 15 minuets it is freezing up on the front.

Is the entire front freezing up? or is it only a few rows?

If the entire coil is freezing up you have one of these three problems (or maybe a combination of them):
1- you are setting the thermostat to too high a setting (start at a lower number and let it run for a good 10-15 minutes before rising a notch or two, another 10-15 minutes again, etc.)
2- the filter OR coil OR both are filthy and the condensed moisture instead of dripping down to the condensate pan is holding tight by the filter/coil, restricting the airflow which in turn brings down the temperature of the coil causing the freeze-up
3- you're running at the lowest speed together with too high a thermostat setting...increase to a higher speed and lower the thermostat setting.


If only a couple of rows are icing-up, you have a low refrigerant condition (likely a leak)


Lastly, if the compressor is not running continuously but is rather running for a little while, then stopping, and so on and so forth, then you may have a defective compressor which is likely overheating and tripping the internal thermal overload (not yet dead but on its way to the grave)

I set the thermostat at the lowest setting that will make the compressor come on,the compressor comes on and stays on but no cool air,it's just like fan.I checked the amp draw and it shows lower than what the amp rating is as the compressor comes on and keeps running just no cooling.After a few minuets the front freezes up almost across the front.If I turn the thermostat down the compressor goes off.

The entire coil icing-up suggests two things:
1- insufficient airflow (grossly insufficient), and possibly also a
2- defective thermostat switch

water turns into ice at 32F or below. You cannot possibly have a low refrigerant charge there and still see the entire coil freezing-up

The amp ratings are almost always lower than the nameplates indicate. The value shown is an upper-limit that is reached under the worst of indoor/outdoor conditions...say, 100F outdoors and your room being very hot after a full day with the a.c. off.

Thanks for your help and info.You think that I need to change the thermostat?I tried to adjust it and it did not seem to do any good.

You need also to address the issue of the possible low airflow. Does it feel like the air coming off the supply vent with a weakened strength (compared to what was the case when the unit was new)?

Yes, I do believe that thermostat is not working as it should. Does it have a capillary tube (the sensing element) that perhaps broke-off?

Before it ices-up, is the entire coil real cold to the touch?

No supply vent,window unit,air flow coming out of the discharge strong.No the evapaorator does not feel cool.I checked the coils and they seem clean,not a lot of blockage.The filter is new.I can switch from colder to just cool on the thermostat and the air coming out of the unit feels the same.I put a thermometer in the vent during cool and then turned it to colder and colder,no change in the air temeture

I don't understand how the ice builds up if the coil does not get cold. I'm missing something...:thinker:

After the unit has been running it gets frozen over on the front,the compressor is running,the blower motor is blowing.I haven't pulled the unit out,but as far as I can tell the unit looks clean.I don,t know what is going on.

I could not find a match (with the info given on your first post) for a Carrier unit with the M/N you gave. Pls double check.

Is this a heat pump?

Ok I re- checked the model no and that is it XCA63D it's a 17,000 BTU cooling only unit.Thanks for all your help,as I said this unit is old,I might just replace it.