How or where can I find out how many tons my air handler is rated for? A/C problem?

I am having trouble with my A/C. The blue pressure [and I may have this backwards] or freon pressure is 70psi, but the head pressure, or red gauge is at or close to 250psi and there is no leaks that I can find, the filter is clear, intake registers are all clear, the condensing unit outside is clean and free of obstruction. All of the dampers are fully open and airflow seems to be good [from all the vents], but id does not blow cold air. Instead, the coil freezes over. I have been told this could be due to a low freon/coolant pressure, or air obstruction but as far as I can tell along with the A/C service person it is not. He says I need a new system, but I am not convinced because though my system is a 10 seer system, it is only 7 years old. It doesn't look like I can access the underside of the coil to inspect it without tearing apart the air handler, so do I need a new one? Or can the coil be removed and serviced?





I would really appreciate any input and thanks in advance.

How or where can I find out how many tons my air handler is rated for? A/C problem?
Check your air flow; make sure the belt is good if its belt driven, or the blower is tight on the shaft if it direct drive. Also check the the blower is not excessively clogged with dirt; this will decrease your air movement. You will need to check the evap coil for dirt or blockage also, do this ASAP. With those pressures, it is probably R22 for refrigerant, and they sound good. I think it is air flow, but it also can be air in the closed system, which would involve recovering the refrigerant,, changing the drier, putting a vacuum pump on it, and recharging it. Air exerts its own seperate pressure, and can give higher than normal readings.
Reply:Check the model number. They go by 12's. If you see a 24 in it it's a 2 ton. 30= 2.5, 36=3 and so on.





I would get a second opinion. There's so many electrical points that could go bad. I doubt you need a new system.
Reply:It sure sounds like an air flow or low freon problem. You may want to check to make sure the condensate drain is not plugged that can cause water to collect on the coil and freeze. To find the tonnage look for the model # on the unit and look it up on their website.


12,000 BTU per ton


400 CFM per ton


This info may actually be on the unit. This should be enough to figure out the tonnage. You can pull the coil to service it but usually there isnt much to service on a coil unless it is leaking.
Reply:Have the repair person evacuate the system,replace the drier, evacuate (leave on a vacuum pump 5 hours) recharge the system.
Reply:It could be low refrigerant but, if the suction pressure is 70psi and it's an R22 system, it should not be freezing. 70psi on the low side equals a saturated evaporator temperature of 41°. That means it would be impossible to freeze water on the coil. If the coil is flooding and there is a lot of pressure drop in the suction line you could see frost near the compressor.





Those pressures actually sound pretty good. On a really hot day that head pressure (250psi) might even sound a little on the low side if it's 100° outside.





Your numbers do not sound right for freezing the coil. Make sure everything is clean before you go any further. Maybe your filter is clean, but your evaporator is actually dirty anyway.





It's possible for dirt to build on an evaporator even if the filter has been change on a regular basis. Especially if you have been buying the 99 cent filters for the last 7 years.





With those kind of pressures and that kind of air flow nothing you are saying is making any sense. The air should be cool and there should be no frost. You need to redo your pressure checks.