A/C Concern

[bulldawgs75]

I have a Honeywell RTH7600D and my T-stat is scheduled to go to 78 when I leave for the day and drop to 72 at 2pm. I get home at 6 and it's at 76. 4 hours to cool 2 degrees seems excessive. My T-stat never cools down to set temp until sometime overnight. This just started happening this season. Any suggestions?


BTW my vent blows out 56 and my return registers 76.

Thanks

Shawn

[kpc01]

sounds like the system is working if its blowing cold air out while its running...when you get home make sure the stat shows that its running (it will say cool or sometimes have as snowflake). doesn't make sense to take that long to cool if its blowing 56 degrees out of the vent. Only other idea is if your house is that poorly insulated but that'd be a fat chance. That would be like leaving the front and back door open all day. I'd check the stat first since its the least expensive and the system seems to be doing its job.

[Bad03Cobra]

I would have a service call, have them check to make sure you are not low on freeon. Just my .02

[bulldawgs75]

I just bought the stat last night and installed it and my freon was just serviced 2 weeks ago. i have good low and high pressure. I had too much freon so we brought the pressure down to std pressure (76 i think) it was at 86 i believe on the line outside.

[ceyko]

So you had your AC serviced, that's good. What about your filters? If dirty they could affect air volume.

[Fast Fox]

Go back and check the setting on the clock on the thermostat. The time may be off. The thermostat and the unit may be doing their jobs but just at the wrong times. Mine did that once and drove my crazy till I figured it out.

Buy one of those little thermostats that has a probe like an icepick and stick it through the canvas expansion joint on the air handler. That way you can read the temperature right at the coil. Mine runs about 48 degrees when the outside unit is on. Check the lines going to the outside unit. The suction line (Big One) should be sweating moisture and cold to the touch. The other smaller line should be warm. The old serviceman's saying "It's sweating back to the pot" is pretty close to right as an indicator that things are close to right on freon charge and airflow across the coil. That means the freon charge is right and the filter is clean and the coil inside is not restricted. If the unit is too small for the job and the heat load is high like it is the past few days, there will not be the temperature difference in the suction and pressure lines even though there is a proper freon charge and good airflow. AC units that are marginal will not survive at temperatures like we have had the past week. I have even seen water sprinklers put in front of the condenser coil outside to help cool down the freon if the fan won't properly do it. Almost like a cooling tower on a big commercial unit.

[Progres1]

I just bought the stat last night and installed it and my freon was just serviced 2 weeks ago. i have good low and high pressure. I had too much freon and we bled it off to bring the pressure down to std pressure (76 i think) it was at 86 i believe on the line outside.


Freon charge needs to be set by superheat not pressure. Systems are running around 16 degrees super heat right now but it depends on what the indoor and outdoor temps are at the time you are checking the system. I have been seeing the lowside pressure at around 80-85 psi with a 64 degree line temp at this time. You might want to call a qualified tech if problem keeps happening.

John Sheffield

[JESmith]

+1 about getting a GOOD tech. PSI sounds a little low for the outside temp right now. Also get your coils cleaned. Inside and outside. AC can't work properly if the coils are dirty and disrupting airflow.

[1badford]

Superheat is the only way to correctly charge a system. I would also change the statement about letting some freon out. Never know when the EPA is watching.

[jyro]

get the attic temp down, the temp in the house will follow.

[bulldawgs75]

I think my a/c problems are fixed with the help of Mother Nature. Yesterday came home to a nice temp of 72 (which is where I have set to at 2p). I think these 100 degree temps is the culprit. I made need to look into an attic fan (solar). Thanks for the advice people.


Shawn

[bulldawgs75]

Superheat is the only way to correctly charge a system. I would also change the statement about letting some freon out. Never know when the EPA is watching.

fixed

[Littlemoney]

Freon charge needs to be set by superheat not pressure. Systems are running around 16 degrees super heat right now but it depends on what the indoor and outdoor temps are at the time you are checking the system. I have been seeing the lowside pressure at around 80-85 psi with a 64 degree line temp at this time. You might want to call a qualified tech if problem keeps happening.

John Sheffield

I agree with John, the ones I have been doing are around 85. I have been lucky tho, line temp avg has been 53-57 and this being the heat of the day.

[jyro]

I think my a/c problems are fixed with the help of Mother Nature. Yesterday came home to a nice temp of 72 (which is where I have set to at 2p). I think these 100 degree temps is the culprit. I made need to look into an attic fan (solar). Thanks for the advice people.


Shawn

you can count blades turning in full sun. they turn at about 150rpm
compare that to a powered one that runs at 1075 and you'll see why they don't work as well for cooling an attic as a 110v with a thermostat.

[Mixedup]

+1 about getting a GOOD tech. PSI sounds a little low for the outside temp right now. Also get your coils cleaned. Inside and outside. AC can't work properly if the coils are dirty and disrupting airflow.

Any good techs on this board that service the Little Elm area? Pls PM me

[kingjason]

Just out of curiosity. How much does a coil dip and fan cleaning run. My inside unit is oldddd. I also think they skimped on changing air filters since the guys son lived there a while. I cant get my house under 79 when its over 100 out side. I have had the insulation done, even over the garage, I went into the air box and sealed off where it was pullingair from the attic, my windows were just redone however some were not great. I sealed the A/C unit off from the garage. House is only 1500 but kills me during the summer. MY last house had same issue till I went up a ton on the units but dont think I am going to live here long enough to justify a new unit. Also has the weird a/c ducts that are like long dryer hoses. No problems with ventilation in attic since I have a concrete tile roof that vents great. Only issue maybe is I have a dog door but I had one on the last place too.

[Progres1]

we charge $550. to remove evap coil and clean and reinstall if you need this done call our office at 817-468-9922 or go to www.checkmyac.com

Thanks John Sheffield