Hello, in my home I have a Rheem Classic 90 gas-fired furnace with a Rheem Central A/C system. I am pretty handy with most DIY projects but I am just now learning how A/C works so hopefully I get these terms right....

A few days or so ago I noticed the A/C wasn't keeping up with the thermostat setting and I took a look at the condensing unit outside. There was icing on the insulated pipe going back into the house, and I traced icing back all the way to the basement unit. When I took the cover off I found the coil covered in thick ice, including the small copper lines.

I let it thaw overnight, put in a clean filter, and tried it again the next day. I let it run for about 45 minutes and it still couldn't bring the household temp down, so I shut it back off.

Last night I took the cover off the condensing unit and turned it back on. It *sounds like* the compressor is coming on, and the top of it started getting hot to the touch. The condenser fan is definitely running, and in the right direction. The capacitor does not appear bulged, although I have not taken it out and run any electrical tests on it yet.

The system is original to the house and was manufactured in 1997. The outdoor unit cover says "10 Seer" and "Scroll Inside" (which I assume means it uses a scroll compressor).

Based on what I've been reading/watching/researching it sounds to me like the most likely issue is a lack of refrigerant? It uses R22, which I'm understanding to be much more expensive than whatever is used now (R408?). Is there any further testing or troubleshooting I should do at this point, or is it pretty certain that that is the problem?

If that is the problem, should my next step be to get an HVAC tech to test it for leaks, and if none found, recharge it? Not sure how much it would cost to replace the whole system with a new one, but I can't imagine it being comparable to a simple recharge, even if R22 is more expensive. Does that make any sense?

(I know the system is old, and believe me if I had the money I'd probably have an easier time stomaching a replacement, but money is tight and I don't know if we could tolerate a huge system replacement bill right now.)

I'll attach some images which hopefully are useful in some way. Thank you for any help!

 

Welcome to the best DIY forum on the Internet. Unfortunately, your problem may not have a DIY solution.

An iced over evaporator (cooling) coil is a classic sign of one of two conditions. Either the airflow through the coil is insufficient (dirty filter, blower running too slow, dirty coil) or a low refrigerant charge. If you have a normal airflow through the system when the coil is not frozen (like when first started) then the idea of low refrigerant is the most likely.

A new system will be the most expensive fix but it should also last the longest. Finding and repairing the leak in your existing system may be extremely difficult, especially if it is a small leak in the coil itself. I would probably call a couple of repair companies and discuss the symptoms. Recharging, if only a tiny leak, may give you a few more years of service at the lowest cost.

 

Those 10-SEER units with a scroll compressor were excellent performers.
If it is low on R-22 the system should be checked to find the leak & fix it if possible.

Could also be a liquid-line filter-drier restriction or blower wheel blades filled with lint & an insulated/plugged evaporator coil.

I would keep that 2.5-Ton unit working if at all possible.

 

Are you able to turn off the outdoor unit from the thermostat?

After you turned the system back on after defrosting, was the suction line cold?
(The suction line is the ~7/8" copper pipe that had ice when it was frozen)

 

Hi, thanks for the replies so far.

Yes, I am able to control the unit from the thermostat.

The blower wheel seems clean, and I'd really like to clean the coil fins, but I can't for the life of me figure out how to get my hands and any tools/spray in there. It doesn't give me a space to get under the coil (on the dirty side), and there doesn't seem to be any more paneling I can remove to get access. :\

Houston204, I ran the system again for maybe about 5 minutes and that pipe didn't feel cold to the touch, it pretty much felt like ambient temp (although the compressor got somewhat hot as I mentioned). Not sure if 5 mins was enough for it to cool that pipe. I didn't think to check that when I ran it the first time (for 45 minutes). Should I run it again and see?

 

I have been running it for 40 minutes now. The indoor temp has come down 2 degrees, and even that is probably due to the outside cooling down (it's late at night and it's raining), and the air from the vents still feels like "room temp." I ran out and checked and those lines running into the house from the outdoor unit both feel like they are around ambient temp, and not cold.

Also, I can't see much of the coil fins, but what little of it I can see looks clean (no buildup/covering of crud that I can see).

 

I would 'NOT' run the A/C in the rain with low outside ambient temps; not good for the unit; especially with very little heatload on the indoor coil. too.

 

Oh, I didn't mean it was low temps in absolute terms, just that it had come down as the evening wore on... it was still 80+ degrees outside.

At any rate, I ended up having an HVAC guy come a couple days ago, and he recharged the unit. He said he thought it would last at least thru the summer, being that it was not completely empty. He also noted how filthy my outdoor coil was, so I cleaned it today.

So about $350 later, we're back in business.

Lots of lessons learned here, thanks everyone!

 

The indoor coil could also be insulated with lint, & may need cleaning along with the blower wheel blades.