Central ac help

[heyttown]

I have a carrier central ac unit that has been here since I bought the house in 2000..I have not had to sink a dime into this unit at all so I consider myself lucky and thankful..Although with this heat wave much of the north the ac has been used a lot this year already. It seems to be struggling to keep the house set at 75..Runs for long periods of time and is off short term...Now I understand my house insulation and airtight issues effect how often the ac will run, its just this season it doesnt seem normal like previous years.. It blows pretty cool air even in the upstairs...Im wondering do the units need recharged even if its blowing cool air? I was under the impression that it will only blow warm when a recharge is needed.

Granted its 100 out today with heat indexs pushing 110, so I knew the ac would run alot..but set at 75, its holding the temp at 75, but I havent heard it shut off in a couple hours... not good for my electric bill.

Any ideas or thoughts?

 

[dlngr]

Re: Central ac help

Turn up the temp.Mine's set at 78 today,and it's still running quite a lot. 78 is comfy but not 'chilly'

 

[heyttown]

Re: Central ac help

I was mistaken, it was set at 76..I turned it up to 77 just to get the unit a brief rest after running nonstop for so long...When I turned it up to 77 it turned back on in 10 minutes or less...granted it was only 1 degree, but not much rest..

 

[Tim Frank]

Re: Central ac help

I was mistaken, it was set at 76..I turned it up to 77 just to get the unit a brief rest after running nonstop for so long...When I turned it up to 77 it turned back on in 10 minutes or less...granted it was only 1 degree, but not much rest..

Most of the work it is doing is pulling moisture out of the air.
At extreme heat level as you are experiencing now, a properly-sized unit should run a lot...most of the time.

Doesn't sound like you have a problem.

You could try setting to 78.

 

[fishrdan]

Re: Central ac help

It seems to be struggling to keep the house set at 75..Runs for long periods of time and is off short term...

That's exactly what our AC unit was doing last year, struggling to keep up and barely maintaining 77, running for 20 minutes to an hour minutes and then off for 5. I'm down in the desert, so seeing 100-110* temps is not out of the ordinary, been 100+ the past month, low humidity though. I had a HVAC guy check it out and he added freon, couple pounds if I remember right (maybe not). The AC now runs for 5 minutes and is off for 20 or more minutes, even in the afternoon heat.

What is the air temp coming out of your ducts, compare it with the ambient air going in, what's the temp drop? Wedge a thermometer in a duct for a couple minutes to get a temp reading. Before our AC was recharged it was pretty bad, something 65*, after the AC recharge it's around 56-58*. The HVAC guy seemed happy to see those numbers, 20*+ temp drop.

Hopefully hrdworkingacguy drops in, he's pretty darn sharp with AC stuff, does it for a living.

(Oh yeah, our coil was 1/3 frozen up when this all came about last year. I had to turn off the AC for several hours to unfreeze the coil, before the HVAC guy could work on it, and get good readings.)

 

[rivermouse]

Re: Central ac help

I assume you have had the "coils" cleaned. When a layer of dust/dirt builds up on them the unit will run hard and poorly cool. It is just a matter of spraying the coil down with simple green and washing it off with plenty of clean water. Dirty air filters will also make it coo lpoorly and run to much.

 

[Tim Frank]

Re: Central ac help

^^^^^ +1 on the Air filter.
Have you changed it recently?

 

[Scott Danforth]

Re: Central ac help

change the filter
clean the coils
Call an A/C tech if these two simple things do not help

for what its worth, Just had the A/C system replaced in the house here in Wisconsin. two cracks in the line, condenser going bad, and a bad A-coil. house is only 15 years old.

I have my A/C set at 78 in Wisconsin and 85 in Florida (about 10 degrees cooler than outside). too much of a shock to the human body to go in and out of 20 degree temp changes. plus it keeps my electric bill closer to the palatable side.

 

[Georgesalmon]

Re: Central ac help

Had a problem keeping temp inside at 77 two days ago. Went up to 80 inside, therm set at 77. Yesterday morning I took top off of unit outside and used a vac to clean fins, then sprayed fins with orange cleaner (no simple green or air cond cleaner at home). Sprayed with water a long time inside to out and outside to in on the fins. Put back together and it kept the house at 77, even shuts off (which it did not do at all before). Yesterday was hotter than the day before so I think that did it. Bought the place three years ago and never cleaned them and don't know how long before I bought the house they were cleaned. I'm gonna clean every year from now on.

 

[halfmoa]

Re: Central ac help

As Scott D said, change the filters and wash the outside condenser. If you're desperate then install a low pressure patio mister on the outside unit. They use very little water and it can make a big, BIG difference. When I did commercial refrigeration we had more than one customer that installed sprinkler systems on their condensers and they didn't have to call us nearly as often in hot weather.

With outside temps in excess of 100 degrees it's expected that a residential unit will run almost continuously.

 

[Tim Frank]

Re: Central ac help

With outside temps in excess of 100 degrees it's expected that a residential unit will run almost continuously.

^^^^^^^^^^^^^^^^^^

 

[hrdwrkingacguy]

Re: Central ac help

With outside temps in excess of 100 degrees it's expected that a residential unit will run almost continuously.

The 100 degrees isn't the reason it runs continuously, its the 70% humidity...its 110+ here most days lately, and both my units are on for 10 minutes and off for 20 like they should be here...A little bit low on refrigerant or a little bit of a restriction or a dirty coil, will cause a unit that should run a lot and dehumidify to run a lot and not do what it should...As a homeowner you should be able to tell the difference between how it used to work and how it works now, and decide if you need to call someone...

 

[heyttown]

Re: Central ac help

Well I had a friend stop out with some gauges and a Fluke temp probe and he measured the temp on the insulated copper line, and was reading his gauges. He said I was just under the limit for a normal level, so he added some freon and got it within normal levels...I havent noticed much change, but the heat wave has left (thankfully) also.. I am now looking to boost my attic insulation, which I will start a new thread for...Thanks for the help.