HVAC Unit. Repair leak or replace?

[Mr. Goodbar]

I opened up the panel while the thing was running. I’ve checked every restriction point, even had a snake cam in the blower and coil. All looks good and clean. The evap coil has some ice formed on it as do the copper lines, likely from low refrigerant(?). I let that melt and started it back up but it starts freezing again in a couple minutes.

If the lines are freezing up then it's low unless the indoor fan just ain't running

 

[sparked1]

Believe it or not, that Nu Calgon leak fix can work. It won’t always work, but it’s worth a shot. We have a ton of units limping along with that stuff, but if the leak is bad enough, it won’t fix it.

I just put a 2.5t system in with a furnace for around $4,500 in the house I just sold. I may could have got a better bro discount from some of my contractors, but I am holding that card until I build a new house.

So did they replace the entire air handler/heat exchanger/furnace as well? And I’m assuming they ran new suction/refrigerant lines and not reused the existing?

 

[harrycalahan]

Those evap coils have so many soldered joints (failure points) it’s ridiculous. Do current systems still use this design? Shouldn’t they be made of aluminum to prevent rust and corrosion?

https://highperformancehvac.com/copper-aluminum-coils-condensers-evaporator-coils/

 

[sparked1]

If the lines are freezing up then it's low unless the indoor fan just ain't running

Airflow is strong at the supply vents. I put gauges on and low side is around 30psi

 

[Mr. Goodbar]

Those evap coils have so many soldered joints (failure points) it’s ridiculous. Do current systems still use this design? Shouldn’t they be made of aluminum to prevent rust and corrosion?

Brazing joints not soldering and yes & no depending on the brand

 

[Hayata]

So my neighbor takes care of my A/C 'cause he's in the biz.

He told me something I had never really thought of before - well, because I'm not in the biz.

But when a unit is charged at the factory there is lubricant in the freon that helps lubricate the insides of the compressor.

When there's a leak you replace the freon with fresh freon but without the lube.

So when you refresh your system as much as you have - I'm guessing there's not a whole lot of lube left in the system.

And with that little knowledge that I have that may or may not be actual fact - I still say replace the whole kit and kaboodle.

One less thing to worry about for the next 10 or so years...

 

[Mr. Goodbar]

Airflow is strong at the supply vents. I put gauges on and low side is around 30psi

That's extremely low

 

[Zeake]

Replace with the highest efficiency you can afford.

 

[mtnsmith]

paging @captdave77

One of my units appears to have a serious leak. It’s 12 years old. Tech came out and recharged it but was low again a week later. Bought some Nu Calgon Easy Seal leak stopper and recharged again. This time it lost most of the freon in 24 hours!

I believe I could easily spend $1500 finding the leak (evacuate system, fill with nitrogen, patch leak, refill system, sounds complicated and expensive) plus what I already spent on R22 and service. And that doesn’t guarantee me anything. A new unit is around $4-5k. Seems I’m better off just buying a new unit.

What am I missing? Has anyone had success with finding and plugging a leaking A/C unit? I’m about 90% certain the leak is in the evap coil. What a racquet.

It does seem that a lot of systems made in the past 18 years tend to develop those hard to find leaks. Mine is about 29 years and still running, but had to top off for a few years back, but tightenned all the nuts (old system that was screwed together) and ok past two years. Understand there are several new r22 replacements (like r48a I think) that can be dropped in with the only downside is you wind up with a medium that there is no temp charts for. But if you can top without them you will be ok as some day it will all be the new stuff. Understand they do this all the time in Europe.

If they can't find any leaks outside the coil, then you might have it repalced and fill system with new r22 replacement that is compatible with r22 oils and seals.

 

[Mr. Goodbar]

So my neighbor takes care of my A/C 'cause he's in the biz.

He told me something I had never really thought of before - well, because I'm not in the biz.

But when a unit is charged at the factory there is lubricant in the freon that helps lubricate the insides of the compressor.

When there's a leak you replace the freon with fresh freon but without the lube.

So when you refresh your system as much as you have - I'm guessing there's not a whole lot of lube left in the system.

And with that little knowledge that I have that may or may not be actual fact - I still say replace the whole kit and kaboodle.

One less thing to worry about for the next 10 or so years...

Refrigerant has oil in it. I don't underatand what he is saying