AC Struggles

First check the basics. Make sure the filter is not dirty. Is this a window unit or CAC system? If its a CAC system, is it used in combination with the furnace ducts or seperate ducts?

First check the basics. Make sure the filter is not dirty. Is this a window unit or CAC system? If its a CAC system, is it used in combination with the furnace ducts or seperate ducts?

Filter (cheap blue fiberglass) is new. It is a CAC system sharing ducts with the furnace.

It has operated better in the past. It just doesn't seem to be performing now.

Check if the pipe at the air handler or at the compressor feels ice cold and is sweating. If its not, its probably low on charge. If there is a sight glass outside , you should see occasional bubbles flow by. If its cloudy or foamy, you could be low. If that checks out ok, make sure your supply and return ducts on the lower floors are shut, and make sure the upper floor ones are open. ( maybe there is a damper someplace that has been shut) Cold air sinks, so you want to push all of the air to the upstairs and let it migrate down. On the same note, hot air rises, so you want only the upper return duct open so it can pull all of the hot air out of the house. A CAC system doesn't just dump cold air in a room, it removes heat and humidity, and thats why the return air is important and works properly.

Get it serviced and cleaned, the interior coil could be clogged and freezing up, you may have to cut and access hole to get to the coil, it could also be low on freon. Closing down vents could make things worse by reducing airflow over the coil. Is the blower wheel dirty that reduces airflow, has the outside unit been cleaned. A pro should go over everything.

Say what? I don;t know of any heating/cooling pro's that would agree with this. Sure, you can close a few registers on the lower level during summer to help the balance. But all of them? Never seen this done.

And I'd suspect choking off the system by closing ALL the first floor returns isn't a smart thing to do either.

Possible, but there are other potential problems.

Dirty coils Restricted air flow (dirty filter) Reduced air flow, such as the blower not working properly.

The outside coil may not look dirty, but it can have a film of gunk that requires a cleaner sprayed on and then rinsed.

You can figure about $100 minimum for service, more if a charge is needed.

Probably. About $456.34

Of course, there are several reasons why an AC might not work properly. Since the unit is 11 years old, it really should be serviced by an AC company.

You wouldn't drive your car for 11 years without an oil change?

Just freeze the coil if you do. Not good advice.

Well since this might not a true dedicated CAC with the ducts probably close to the floor, I was merely suggesting arranging the ducts in a way that would produce optimal results. What I should have said was adjust the ducts in a way that less cold air to the lower floors and more to the top floors, same with the return.

But, the unit perform OK in the past. Unless the ducts/registers were changed that does not really solve the root cause of the problem.

Measure the temperature of the air coming from the AC. It should be about

"Buck Turgidson" wrote

Buck, if you havent had any coolant added in 11 years, thats a likely spot. Prices vary for that but apt to be in line with about 100$ plus whtever they charge locally for a regular checkup and cleaning of the coils. Call it probably 200-275$ total as a reasonable guess? May obviously be a bit more or less where you are.

This assumes you've done the obvious and changed any filters etc (about 5$ for a new filter here and takes all of 3 mins to swap out the old one).

My area is a little cheaper and we got an estimate in spring, 175$.

It could be many things, including:

-- ductwork or plenum has sprung leaks (the most likely scenario, IMHO)

-- bushes/dirt/other obstructions affecting airflow through the outside unit (also pretty likely)

-- compressor not running at top efficiency due to damage, need for lubrication, weak run capacitor, etc. (i.e. service call stuff)

-- air mover fan not running at top efficiency due to similar factors

-- crud blocking the indoors coil

-- higher humidity than the times you remember when it operated better

I think that is less likely. He'd have had heat problems too if so. Definately possible, but wouldnt be my top pick. (Buck, check the attic and see if it seems to be untaped, if so use the proper tape and retape it).

Possible, but apt to be something he'd have seen already.

Might be but he'd note an airflow drop right?

Same right? Airflow would be impacted.

Likely.

I still think if he's not had a bit of coolant added in 11 years, thats apt to be it. Combined probably with dirty coils if not serviced in 11 years.

These closed systems should pretty much _never_ (even in 11 years) require additional freon, IMHO.

My condenser unit has gradually moved about 7 inches to the right in the last 25 years. It's hanging off its slab a little bit. I think if I tried to move it back where it started, I would likely crack the copper pipes. Yes?

Otherwise, if you're right, I'm glad to hear it, because that is one of the three things that could fail, I think, and you're saying it won't.

My system is 29 years old with no freon ever added. Haven't used it this year yet, but it worked fine August of last year.

You shouldn't tell an auto repair shop, or AC or furnace or most any guy what is wrong with something, or what he needs to do, unless one is certain.

If you tell him what to do and it doesn't help, he just did what you told him and he's not responsible that it didn't help. Let him figure out what he thinks is wrong, and why, and then the customer can decide what to do.

Like I said, I don't use my AC much but it's 29 years with no added freon and worked fine last summer.

I feel the same way about automobile tires.

Old copper gets brittle. Leave it. Or build something under the overhang edge.