Gas and Oil Home Heating Furnaces - a/c freezing up

please help, we are hot! My a/c is freezing up. It is freezing up outside (of the house) on the pipes and then starts on the inside(of the house) My husband cleaned the outside unit but he is afraid to take apart the unit inside to clean the coils, is this the problem, do the coils need cleaned, or could it be something else.When it was turned on it ran all day before it started to freeze, and it worked by keeping the house cool, but it froze up after about 10 hours.It ran fine until then. Thanks

First you must defrost the coil. Set the heat/OFF/cool switch to OFF and the FAN auto/ON switch to ON. This will allow the fan to run with the cooling off. It will take 2 hours or so.

Check the air filter. If it was dirty when the unit was running and froze up, installing a new, clean filter of the proper size should take care of the problem.

The filter must completely fill the filter rack so that dirty air will not bypass the filter.

Yes the coil could be dirty. It is a pain to get to and even worse to clean. Most contractors avoid this job as much as possible.
The blower wheel could be dirty as well.

The system may also be short of refrigerant.
Finally, the problem may be all of the above.

thanks for your help. we did change the filter (every month) actually we thought it was freon so we had it filled (cost a bunch)we were trying to avoid taking it apart and cleaning, we are afraid of not getting it back together correctly. so are there any special tools i will need?

You will need a wire brush, flashlight, hand mirror and an assortment of screwdrivers. Latex caulking is good for resealing the coil box after you are done. It washes off with water and it won't bond so tightly that you cannot get it off nest time.

Try to lift the surface dirt off of the coil and NOT brush it down and into the fin spaces. Use the mirror and flashlight to look through the fin spaces for embedded dirt. If it is dirty inside, washing with a stream of water at high pressure can remove much the dirt but often leaves some. You see the obvious problem with that.

Filters are a great long-term investment. You let the filters catch the dirt and throw it away. This prevents future expense and energy waste.

I clean about 5 a coils a week and i use a shop vac and a new toilet brush. i pullthe coil out and up as far as possible to get acess without kink the copper lines and start in with the vacuum. i also ue a soft hose taped in the end of the vacuum so i don't bend the fins. then i brush and vacuum trying not to drop dirt into the furnace which will be blown back into the coil. if the dirt is tough i use a non acid coil cleaner that is self rinsing turn the blower on and let it blow the soap all the way thru the coil. This is not an easy or pleasant job but can be done usually.
as for the tech probably wants to hear from you so he knows if it leaks in a month or two or takes a year to leak enough to not run right.
I hope this isn't too confusing.