My house A/C is frozen, please help!!?

My house A/C started to act up a few days ago, and noticed a LOT of ice build up on the evaporator coils where the filters go. The filters were not heavily clogged nor were the evaporator coils. I've checked the outside fan and heard the compressor making its normal buzzing noise, everything seems fine there. From what I've researched it sounds like its very low on freon. So my questions are, how is it that if the A/C unit is very low on freon its still able to "freeze" the entire evaporator coil?? Doesn't it need freon in the first place to accomplish this? Second, after I find and fix the leak, will a standard auto A/C hose work to add freon? I know a lot of you will say to hire a professional but I feel that its a bunch of B.S. to pay some jerkweed $500 when I can do it myself w/ a little advice. I know it will be hard to get freon w/out a license (R22) but I will try to get some. Please only respond if you have any real advice other than suggest hiring someone. Thanks

My house A/C is frozen, please help!!?
Wow at some of the answers. I was almost impressed with the App guy, till i read that the least likely reason an a/c will freeze up is being low on charge. I know he's smarter than that and must have used a big macro to answer instead of typing it out himself. If the filters clean, evap is clean, try this first, Cut the stat off, go outside and make sure the unit out there is off too. Might have a contactor stuck. As for why the a/c freezes up when its low on charge. It's easy to just say this. The freezing point drops as the pressure drops. If you read a lot of charging questions. You will see people saying charge your a/c to 65psi. Well, Cant always go by that. But at 65 psi the r-22 temp is above 32F. Once you drop below that mark, umm you got problems and ice. I can answer more in a IM. But for now GL and always take answers from Yahoo Q and A with a grain of Salt
Reply:You have said that you " checked the outside fan and heard the compressor making it's normal buzzing noise" but you did not say anything about checking the condenser coils for blockage as this can cause the evaporator coils to freeze up as well. A combination of the filters " not heavily clogged" and the evaporator coils not heavily blocked and the condenser coils not heavily blocked can cause a freez up. Before going out and illegally obtaining some R-22 and illegally attempting to fill the system and possibly over filling the system clean both sets of coils and replace the filters and see if that does not correct the problem. If that does not correct the problem then happy hunting.





The reason an A/C unit will freeze up when low in refrigerant is because the design of the system where it needs to cool large volumes of air there must be sufficient amounts of refrigerant in the evaporator to handle the warm air being blown across it and drop the temperature at least 20 degrees and sustain the temperature for the duration of the time it takes to satisfy the thermostat. The system is charged just beyond the freezing threshold with the flow of warm air flowing across the evaporator. If the evaporator fan was stopped or the air flow was blocked to prevent enough warmth from going across the coils it will freeze up. If the refrigerant were not cooled off in the condenser( where the heat is transfered to from the absorbtion in the evaporator) the unit becomes innefficient and the evaporator will freeze up. The same thing happens if the unit is low in refrigerant, it becomes innefficient.





The least likely reason for an A/C to frost up is from being low in refrigerant. The lines and other components in the system are sealed well some from tight sealing mechanical fittings and others that are welded or brazed together. Unless something happens to damage the lines or coils or a fitting vibrates loose because it was not tightened properly you should not have a leak ever. It is more likely for coils or filters to become blocked with dust and dirt. Low in refrigerant is usually the first thing that the laymen think of when something goes wrong with the system and do a cursory check on some of the other reasons but have already made up their minds that "it needs gas".
Reply:The only times I have experienced this was because the filter was very dirty and/or something is blocking the airflow thru the coils. Make sure the filter is very clean and there is nothing blocking the air flow. You can chip away the ice carefully, but the best way is to melt it with a hair dryer or heat gun. You are right it couldn't freeze up if it were leaking freon. Check the outside lines to see if they are frozen too - typically they are even if it is 90 degrees outside.
Reply:well. I do know it,s probably low of freon, why it freezes up when it gets low, I don,t know but it does. If it,s a window unit, you can take it to a used appliance store and they will fill it for about 30 dollars , which is cheaper than you can do it. if it,s a central air unit, than you can try to fix it your self. good luck
Reply:When my AC freezes up I turn it off until it thaws. Then I restart it and it works fine.
Reply:Yes it is low on freon.
Reply:You have figured out what you need to do so go ahead and do it. The leak may be so small that all you have to do is add the freon. Just make sure you do not over charge it. Yes the auto A/c hose will work fine as long as it fits the shrater valve. Which you may have to install.
Reply:as one of the jerkwads that has the training and license to do this properly i will give you this advice....call a professional. you dont have the training to mess with r22. dont mess with it. dont try putting r134a into the system to top it off. dont try to use regular solder on the system.





most leaks occur in the "A" coil or evaporator.


the reason a unit freezes when its undercharged is that when the freon leaves the expansion valve it encounters a low pressure area (suction side) the lower the suction side pressure gets the colder the freon gas is and the faster it absorbs heat. the reason it freezes the coil is because it is absorbing heat too fast.





that's hopefully enough thermodynamics so you understand the problem.
Reply:This is a fairly easy one to answer --- I could take the time and effort to describe in detail what you need to do on this one , but then I would have to charge you $500 for consultation fees. One of my other "answers" goes into great details on how you can do exactly what you need to .
Reply:you need more airflow. are any of your vents closed off?
Reply:1 You will not have the equipment necessary to fix the leak. If you just start torching on a solder joint and 'freon' is still in the line the joint might break spraying you with very hot oil and very cold 'freon' gas. So decide if paying some jerk weed to fix leak is cheap than your eye sight or possibly your life.





2 If you make it past the leak repair and make it to charging it how will you know when it is fully charged. Every home runs on just a little different pressures. Do you know what superheat, sub-cooling is or even how to calculate it. If you don't I can guarantee that you trying to fix the leak and charge it yourself will mean that some jerk weed will coming to your house to fix the bigger problem that you caused. I see it all the time and just mean it goes from a $100 service call to $1200-$2000 A/C replacement. So go ahead and try to fix it yourself. And for the record most companies will charge extra if they find out that a home owner tried to make a repair.





Oh yeah! We give free estimates.
Reply:Hold on, I doubt if you need a recharge, it sounds as though the AC is not turning off. Shut down the power to the compressor but let the blower run until all the ice melts. Check the coils to make sure the passage ways for the condensate are clear and this water is running properly to the drain. Now turn the compressor power on. Check to make sure the compressor switches on and off as you move the thermostat up and down. If not, you may need a new thermostat. You say the filters are not heavily clogged, well spring for some new ones, they should be changed every 30 days. And if you can, take a Shop Vac and clean the evaporator coils, you'll just help efficiency and save some bucks. Hope this helps, stay cool and good luck.
Reply:when ours freezes we turn it off of course, then use a hair blow dryer on it to thaw it. Then it works again.