I have a 12 year-old unit that has had the capacitor go bad 1/year x 2 years. It is a 3 ton unit for my 1100 sq ft. home.
For the past 2 days, I've heard a loud rumble in the attic. The A/C was still running, although it was very noisy. Today I returned home from work, and the A/C had stopped running. I went outside, and the fan was off, and there was significant ice build-up on the coolant outlet. I read that there could just be frozen coolent clogging the system, so I shut it down for 2 hours and left my hot and muggy home. I returned and turned the unit back on at the thermostat. The fan kicked on, and the compressor kicked on. The rumbling in the attic resumed. No air was flowing in the vents. I went up to the attic, where there was a large metal box where the noise was coming from. I noticed water and rust all along the bottom. I saw a note that the coil was replaced in 1997.

Any advice? Is this unit toast? Any way to fix my problem without paying someone to come out in the middle of the night? :confused:

Thanks!!

I am not a trained HVAC mechanic but had similar ice build up, frozen pipes on another home than the one I currently own. Sounds like there is a freon leak/and/or a bad compressor. See if you can make it until Monday when rates are much lower than weekend rates for a tech to visit and test/check out your unit. My best guess is that since it's 12 yrs old, that you are due for at least a new compressor and/or new coil, air handler. If you have to replace all, at least the new unit will probably be much more efficient and comfortable.

About all you can do before calling a tech is check the air filters. Maybe make sure both the A coil inside and the condenser coil outside are clear.

Update: the compressor outside runs fine, as does the fan. The rumbling was coming from the attic. I opened up the blower fan aparatus: the "squirrel cage" was not secure to the motor. After spending 2 hours taking the thing apart, cleaning it, and putting it back together I realized that the problem was that the motor had worn out its secure attachment to the "squirrel cage" so that while the motor was turning the cage was just screetching and hitting the sides of the case but not really turning.
Can this be fixed without relacing the whole thing?

If the motor shaft or the squirrel cage housing is worn, you might be able to repair it with Quick Metal or JB weld from the auto parts store. I wouldn't expect either to last forever, but how much longer is the whole system going to last? Otherwise, it may be a new motor or blower.

Thanks for the help so far... now I have a new problem...

I ended up taking apart the blower and seeing that the fan was completely disgusting and rusted through. After a very hot weekend without A/C, I took the fan to a parts wholesaler and got a new one. It was harder than I thought to put the motor through the new fan, but after a couple of hours the fan was back in one piece. I set up the system and turned the power back on... The fan was working great...
Then I turned the thermostat off to turn off the fan... only the fan kept going. I realized the motor had just slower down. The motor is a 3-speed. I shut off the power at the fuse box, and of course this shut down the fan.
I'm very confident I rigged the fan the same way it was before- I only separated three cables from the motor, and then put them back. What happened?? Please help!

Thanks