Air Conditioning - A/C Running, but not cooling

I came home around 4:30ish this afternoon and set the A/C to 70 degrees. My wife had set it at 73 before she left this morning and the t-stat read 73 when I came home. It's now 8:45 and it's just reading 70 degrees. It has been humid here, but was overcast when I came home. Currently, it's 70f outside with 87% humidity. Given those conditions, doesn't 4+ hours straight of the A/C running seem a bit much? Especially since it's been cloudy and the sun has been going down?

House is a raised ranch bult in the late 1960's. A/C was added in the early 1990's I'm guessing. We've lived here just a bit over 4 years. I've never had anyone come and do anything to the A/C system. A few years ago, I took the cover off the outside unit and blew out the cooling fins with compressed air. I change the filters on the air handler regularly and clean the honeywell cells(static filter) regularly as well. We've replaced the old style mercury t-stats with a programmable Honeywell when we first moved in.

Details on the sytem.

Outside unit:
Ruud, built in 1990. Here's the label right off the unit:
http://img235.echo.cx/img235/7836/ruudoutside14nc.jpg

Lines off the Ruud. The larger line was cool, but not ice cold. The small line was warm, but not hot. I could see fluid moving through that small sight glass:
http://img235.echo.cx/img235/7645/ruudoutside21tf.jpg

ArcoAire Air handler located up in the attic. It feeds 8" dia flex ducts that run to ceiling mounted registers. I've been up in the attic today and all ducts look good, non are crushed and there are no major leaks from the air handler near the ducting or from the unit itself. Here's the label on the unit.
http://img235.echo.cx/img235/2281/airhandler2sa.jpg


I'm confused as to what could be wrong here. If these systems operate like vehicle A/C, wouldn't the compressor not run if the freon was low?

I figured I'd get some advice here before calling someone to come an look at it. I'm stumped. :confused:

Residential A/C's are not like automotive. Most do not have any kind of pressure switch to shut down the compressor if the refrigerant is too low.
Seeing bubbles in the sight glass is generally not good & an indication of being low on refrigerant.

did you see lots of buble in the sight glass after the systme been running awhile?


With that big filter on the suction line, Looks like the system had a repair once before??

You got a 3 ton unit and should pulled the temp down faster.. How's the air fitlter? Did you have the stove on to make supper?

I didn't see bubbles in the sight glass, but it wasn't exactly a steady stream eather. It kinda looked like the fluid was sloshing around in there. I take it this is a sign of needing a recharge?

Jay,
I pulled the prefilters from the Honeywell unit and pulled the main filter from the return. The main filter looked fine and I ended up putting it back in because without it, the return grate made a whistling noise. Yep, we had the oven on last night. But this thing was running straight even before we turned the oven on. I'm sure it ran the entire time my wife and I were at the gym.

I'm not sure if this system has been repaired before. I don't know much about it since we've been in the house for 4 years and this is the first time it's acted up.

The air coming out of the vents is cool, but not as cold as it used to be.

What's a recharge of 22 usually run?

I would say 1st clean the evaporator coil good and hose down the outside condensor coil and go from there. It could easily take 1 hour to drop 1º in your house depending on the units sizing.

It is very possible that you have a leak but don't depend on the sight glass. They can show just what you're seeing and be perfectly charged. Sometimes if installed improperly the refrigerant will be turbulent and cause you to think it needs charged.

After you get it cleaned up, if it still don't perform the way you think it should call in a pro. The price of a recharge is hard to tell but they really should find the leak and repair it.

I hosed down the outside condensor this weekend, so that should be fairly clean.

What's the best way to clean the evap coil? Vac with a soft brush attachment? Getting to the coil won't be easy, I know that much.

Several questions.

What size is your home-living area with conditioned air?
Your AC condenser is a 3 ton?-I was unable to read plate data?

Is this problem different from the way AC unit has operated in previous summer seasons?

What area of country do you live?
Just interested in idea of average daily high temp and humidity?

How would you describe the insulating properties of your home?
attic,doors,windows,crawl space....

For a homeowner, I believe you have tried to troubleshoot unit as best as possible and should go ahead and have unit inspected/serviced and make certain they check pressures. Let them open/clean coil. No need to pump freon without locating point of leak-this is just a temporary fix without properly solving problem. Ask service/dealer how they locate and repair leaks on first visit.

Good Luck!
:)

Thanks. I tried to check over as many things as I could before posting here.

I'm not sure how many tons the A/C unit is. What markings do I look for that denote the size?

The house is is about 2000-2200 sq/ft. It's a raised ranch and the A/C registers are only in the main level. The downstairs living area and sunroom don't have any registers. The house is located in Connecticut, about 10-15 minutes north of New Haven.

The system seems to be running more than it has in years past. Even on hot sunny days, the system would kick on for a bit, but shut off every so often. Yesterday, it ran for hours straight and it wasn't even that hot or humid.

Daily temps vary greatly. Two weeks ago, we had the heat on. Today, it's going to be 87F with high humidity.

Insulation is fair. The previous owner said she had insulation blown into the walls at some point. The attic is well insulated. There's insulation between all the ceiling joists and about 60% of the attic space is covered in plywood to allow for storage space. Windows are old wood single pane with storms. I currently have the storms in place.

For a homeowner, I believe you have tried to troubleshoot unit as best as possible and should go ahead and have unit inspected/serviced and make certain they check pressures. Let them open/clean coil. No need to pump freon without locating point of leak-this is just a temporary fix without properly solving problem. Ask service/dealer how they locate and repair leaks on first visit.

Your AC unit may be undersized but even so, I believe this is a mechanical issue and still recommend that you contact dealer for a thorough inspection/service and freon charge if needed.

Good Luck!
:)

That's what I'm leaning towards at this point.

Outdoor temp: 84f with 61% humidity right now. My wife turned the A/C up to 73f before leaving today. I'll post here what's going on when I get home.

I didn't see bubbles in the sight glass, but it wasn't exactly a steady stream eather. It kinda looked like the fluid was sloshing around in there. I take it this is a sign of needing a recharge?
Lines off the Ruud. The larger line was cool, but not ice cold. The small line was warm, but not hot. I could see fluid moving through that small sight glass:
Big copper lime should be cold and wet.
Get a tech to go over it and look for leaks for sure. You said on warm days the unit shut off on its own could be the compressor got over heat from low gas to cool it.

ED ;)

Ed,
I'll check that line when I get home.

By shutting off, I meant the t-stat would click and the unit would shut down because the inside temp had reached the set point. Yesterday, it took hours to get to the setpoint.

Ok, here's the update. It's a actuall 73F in here!

However, the large copper line on the outside unit is only cool and not sweating. On a warm day like today, it's usually pretty wet and cold to the touch.

We have a service contract for our boiler, but not our A/C unit (I'm sure this situation will change that.). Should I just request someone come out and do a pressure/leak test and refill with R22 as needed?

CAll A hvac tech to check it for sure . Make sure they check for leaks. But 4 years can be small and a hard to find one but look for it anyhow. If dont find it ask them to put in some dytel. Later on it will show up red where the leak is.

ED ;)

Will do Ed! I'm calling them this morning. Hopefully, they can come out soon. It's been warm lately, so we'll see.

A/C is off today, it's going to be 90. :(

Have them go ahead and clean the indoor section and watch how they do it. Post back on your findings.

Have them go ahead and clean the indoor section and watch how they do it. Post back on your findings.


Not a bad idea. I'll burn up in the attic learning how to do it if it will save me a headache in the future.

Update time! It was hot in the house last night! 82f at 2AM. Yikes!

The guy showed up this AM, I turned on the system and he hooked up the gauges. Sure enough, it was low. He said he should be getting a reading around 32, but was getting a reading of 54. I think those were the numbers at least.

While adding freon, he showed me that there was a pressure switch hooked up to the system. This switch was on the inside, near the compressor. He said it will shut down the compressor if the pressure gets too low.

Jay had pointed this out in a post:
With that big filter on the suction line, Looks like the system had a repair once before??

It looks like the pressure switch is the reason they have the hook ups on the outside of the unit. Good eyes!

Anway, once the freon went in, I could feel the air off the fan getting warmer. Once he added 2lbs of freon, we went inside to check the temp. He had me measure it since he boots were dirty from working around the unit. He said we should have a 15 degree temp difference between the air entering the return and the air coming out of a register. Air in: 77.5f air out: 58.5f. :thumbup:

So, all seems well for now. He speculates that there's a really really really small leak somewhere, causing the system to drop charge. Since we haven't had anyone out since we've purchased the house, he thought maybe this charge would last another 3-4 years. I'm keeping my fingers crossed on that. I did notice that there's not nearly as much swirling going on in the sight glass. Even the first year we were at the house, I noticed swirling in the sight glass.

The guy who came to the house is really cool. He's the same tech that works on our boiler and he always lets me bug him with questions and whatnot.

Sounds like you have a good service tech. Hang on to him. The offer of hot cup of coffee in the winter & a cold glass of tea, soda, or water in the summer go a long way. A piece of pie, cake, or some homemade cookies is a real bonus. Believe me, we remember who treats us well & who doesn't. :cheshire:

I will certainly remember that next time he visits us. It is true, the little things make a difference! :)