[biggles]

temperature drops and rises on a fully charged unit are...at the furnace air handler the return air should drop 18F into the supply air after going across the evap coil and the condenser outside should heat up the days air entering across your legs 10F into you face.the thin Liquid Line should be warm but not supper hot the condenser casing should be super hot in the direct sun like a car hood....but never the LL if it is the condenser might need to be hosed inside out bottom 5 rows....if the charge isn't up to max'd then it will run longer to make the setpoint on that stat the guy that changed the stat sounds like he didn't know how to check a charge....the liquid line is the determining factor on cooling to setpoint if it is gas mixed in anyway off the bottom on that condenser the temp at the air handler willn't be where it should be and results in longer cooling runs on that compressor.....and your wallet.the freon is like air in a tire should always be there..not constanly added to and freon doesn't wear out...

 

[Marty S.]

The outside unit is brand new but how about the inside? Sticking a new condensor on an old evap coil can decrease the capacity of the system 25% so your 3.5 ton could be operating at a 2.5 tons capacity.

 

[tobo1201]

all the registers in the house blow around 58f with return air around 78f is it possible i do not have enough airflow?

 

[yuri]

Did you change the indoor evap coil as Marty asked? If not you have a mismatched system and nobody can make that work properly or 100%.

 

[clocert]

18f drop is OK, check to see if your airflow is strong, it is not easy to check unless you have the right tool, but you should feel the cold air from 10 ft away. If air flow is OK, is the room well insulated ?

 

[tobo1201]

no the indoor evaporator was not changed when the outside unit was replaced why do you think the tech that did the work would not mention this i can not feel air flow at ten feet 6ft at the most i consider house to be average insulated the return vent pulls so much air it seems like it want to suck the air filter up into blower return vent is 16x24 could adding another return fix my problem and can you have to much return air

 

[clocert]

Only feel the cold air within 6 feet is weak. Are all rooms the same, or some room has stronger airflow. Since you have 18 degrees drop, your A/C unit is fine. the problem you may have is either insulation, unusual heat source (for example, big window face West, etc.), or weak airflow.

 

[tobo1201]

thanks for everyones info all the registers blow about the same airflow and i checked them again and they do not blow ten feet 6ft at the most
i removed the air filter for about 10 minutes and air flow increased and temp drop in the house alomost 2f i going to install another return vent and see if this will fix my problem