Split air conditioning system, evaporator unit in attic working but outside unit not running blowing hot air

Your dehumidifier is likely working correctly. When operating and removing moisture, a dehumidifier will supply warm/hot air to your house. Your dehumidifier moves less air than your A/C, so your supply ductwork in your house is oversized for the dehumidifier. This will lead to uneven feeding of your supply duct branches with just the dehumidifier operating.

Since your dehumidifier is installed in the attic, make sure that the ducting connected to it is well insulated. Also make sure that your dehumidifier cabinet is insulated. These actions will help prevent heat gain from the hot air in your attic.

Is your dehumidifier bringing in fresh air from outside? If the outside air is hot and humid, the dehumidifier will supply warmer air to your home.

Some people run their A/C fans continuously to help with the air distribution, but this is a bad idea since it increases energy usage considerably.

DryDog

It could be that it is not charged correctly. Check the insulated copper
line outside if it is sweating and the condensor is discharging hot air, then the ac is doing all that it can. Check the evaporator inside to see
if the drain has condensate coming out of it.

Getting the heat out of the attic is a good idea, but you must have enough make-up air in the attic for the fan. If you do not have enough
make up air, it will start to draw air from inside the house. One way to check this is if you have a gas water heater and or furnace. If you put
a flame by the exhaust pipe in the basement and it blows it out, then you now have a backdraft problem.

Run the AC withoutthe fan, my real guess is the unit is not properly
charged or you do not have a big enough AC unit.

Welcome to FixYa,
Check the Following
Is your filter clean? Look and the evaporator in the inside unit. Is it frosted up? Do you have condensation water in the pan? Go to the outside unit and feel the air coming out of the fan. Is it warm? Now feel the 2 copper pipes coming out of the unit. Is the small one warm or hot? Is the larger one cool ? Is there moisture on it?
Air conditioner runs but doesn't cool at all
If the airflow is good and the air coming out is not cold, your home air conditioning problem may be a temporary problem - your coils may have frozen. Turn the unit off for an hour to let them thaw, then try again. If cold air is now present, freezing coils were the problem; if the problem recurs soon after turning on, you may need to replace the coils. Again, call a pro. If you have ceiling vents in upstairs rooms and the air flowing from them is consistently warm, you probably have leaky or poorly insulated ductwork in your attic. See my Attic ceiling insulation page for more information on insulating ductwork that runs through attics.
Another likely home air conditioning problem if you have good airflow but no cooling is that thebreaker to the outside unit is shut off, which, depending on the installation, can either cause the air conditioning system to not run at all, or to appear to be running but not provide any cooling. If you can hear the compressor fan running outside, the breaker is on, but if the outside unit is silent the outside breaker may be off. If switching it on does not solve the problem, look for the high pressure cut outon the condenser and try resetting that.

Check this Link for Detailed Repair Click here

Hope you got an Idea...Thanks for Contacting FixYa...

1. Check to make sure everything in the condensing unit (outside unit) is running....compressor, fan motor. If you do not have electrical experience, contact a qualified service technician.
2. Check to see if the condensing coil is clean. In many cases this can be cleaned using a garden hose.
3. Check to see if there is any ice or visibly frozen areas. If so, ensure your air filter and your evaporator coil (coil in the air handler) are clean. Ensure your return grille and supply vents are open and not blocked.

Hope this helps. Good Luck! :-)

If the compressor and fan work in the outside unit, and the fan inside (air handler) works, probably the system is low in refrigerant which means there's a leak that has to be fixed and then recharge the unit.

The attic fan is not a part of your a/c system, and you should not run it while you are running the a/c. If you are currently using the attic fan, it is possible that someone wired it so that the a/c won't turn on while the attic fan is on. Otherwise if the thermostat is set below room temp, and says it is calling for cool, then the problem is most likely coming from an issue at the outside unit itself. Make sure to check your fuses, at the fuse panel and outside breaker. Hope this helps

FYI.. the only part of the system that might use batteries is the thermostat.

hi! there,
well we have to do something about that,if you mention of fan spin and it pushes air but no cold enough on it,this refer to blower on compressor, there is fan on outside the condenser,so we are on blower w/c does not blow enough cold air,there are factors we can check,first thermostat try to adjust thermostat to the coldest point,
observed if cold was increasing if not, 2nd have clean the filter from evaporator it may have a clogged, check evaporator if there freezing ice on bottom portion of evaporator w/c cold was coming out,have it clean,cleaning this is done by certified a/c technician,there is problem if have an insufficient cold,this is the symptom of your system was under charge lack of freon,this can check by technician w/ clamp ammeter device.the operating current should be equal to rated current on manual,inform service center about this,have a nice day don't forget to rate me.thanks's

There could be a couple of problems going on. Your fuse on the heater up in the attic is popped.
Your glow ignition is broken.
Your spark ignitor is bad (if that is what you have)
GAs valve is bad.
Or the vent sensor is bad, meaning that the exhaust fumes are not going anywhere.
Now when you turn on the heater your condensiing unit outside should never turn on unless you are calling for AC. Now if the ac is not coming on there can be more problems.
Disconnect fuse is popped.
Wiring is wrong going to the heating board.
No wires for AC going to the thermostat

Is your unit a Split system where one unit is inside (attic, garage, utility room) and another outside?? Is the outside unit unit running?? Is your thermostat electronic or the regular slide mechanical type??

Open the access panel on the air handler in the attic and take a look at the evaporator coil. If you have no airflow, and you just changed the air filter, then you probably have a buildup of airborne crud on the coil that's blocking airflow. If you do have a layer of buildup blocking airflow through the coil in the air handler, just take a $5 fin comb and scrape all the crud off the coil fins. This can make a dramatic difference. Hope this helps! ;)