Looked on unit outside and it has about 1/4" of ice buildup on unit. i turned off thermostat for about 7 minutes and outside unit never turned off. I have noticed a lot of condensation at the base of my air duct in the basement. I'm not sure what's going on...

check thermostat turn off system wait 3 to 5 minutes turn on to cool and turn thermostat to coolest setting if no compressor test thermostat and compressor check filter if dirty and coil iced turn off and lit defrost and change filter if coil warm and unit running compressor internal damage or low freon

The thermostat should run at the temperature desired for as long as your setting. If it cuts out early, then in some cases the humidity is causing ICEING (Ice buildup on the coils) and needs to sit for a time until it melts off. A manual override will keep the device in operation, but the cooling is usually the air crossing over the iced coils and entering the house. Factory service will locate the problem.

Unless you just installed or had the thermostat installed recently, I would not point at the thermostat as the problem. With what you have described I would suggest have your units serviced as it sounds like a loss of charge, or failed defrost control board. The "Aux" comes on when the unit is using secondary heating (electric heat strips). That occurs when the demand temperature (what you set it to) in Heat mode is more than the current room temperature, usually ~2-4 degrees higher. Also happens in defrost mode. Defrost is a heat pump cycle that melts any build up of ice on the condenser unit (outside unit). That process is simply the unit running in cool mode which will heat up the outside unit to melt any ice. Defrost cycles vary with manufacture but usually you can tell if is in defrost by looking at the outside unit, during defrost the unit will be warm or hot sometimes there is steam and the compressor will be running but not the fan. Defrost only happens on heat pumps in "Heat" mode. Rheem has a 10 yr compressor and parts warranty, so call the installer or Rheem authorized service company.

Check behind and underneath for dust buildup, sounds like your compressor needs cleaned on the outside, the dust is causing it to overheat and retain condensation, hence the ice buildup. Easy thing to check, good luck.

Hello, does the outside condensing unit start when the thermostat is set to cool? if so, the relay on the integrated control board is bad and the board must be replaced. If the outside unit does not start then most likely the thermostat is bad.

On the split system 1. Can burnout from defect, lightening, etc .. 2. Only way ice will buildup back to outside unit is LOW LOAD.. either from dirty filter, dirty coil or fan blades caked up with dirt. 3.. Poor airflow will cause the poor cooling $ Outdoor unit most likely has a low pressure switch causing the outside unit to shutoff until pressure rises.. Has this helped ?

Switch the thermostat from heat to Aux. or emergency heat till the outside unit thaws out. This will shorten the life of the outside unit considerable running it all iced up.

Go outside and hook a shop vac up to the drain pipe outside and let it sit there for a couple minutes your red wire is most likely broken by a float switch and it may be backed up

if one or few pipe may not aproblem may be the thermostat is aet to very low cool anf the fan on low speed or the thermostat is defective also if this icing is growing up means
-1 evaporator need cleaning
- 2 a smll freon leakage

If the frozen side is colder than normal and some extra frost is forming where the fan blows,and there is ice in the bottom of freezer compartment, and the cool side is not cool enough, their is a good possability the defrosting unit is not removing all the frost and ice . the defrosting unit has a timer (usually near thermostat) that turns off the cooling fan and compressor and turns on a small heater around the evaporator ( about 20 minutes every 2 days) (evaporaror is cold heat exchanger coil inside the back wall behind a cover near the recirculating fan0, the fan circulates air to both compartments through two small openings, if these openeing are closed by ice buildup cool air can not circulate to the cool side. cure 1. remove all food and leave fridge off for 24 hours with doors open (take precautions to ensure children can't get locked in side and suffocate, if you get a qt of water in bottom of unit (may leak on floor) ice buildup that the defrost heater can not remove melted and was your problem . turn frig on replace food on unit. cure 2. turn frig off, remove food from both sides, remove shelves that block access to evaporator, remove cover over evaporator if you see the evaporator coils free of ice look at openings (2) to other side, one may be blocked with ice the other with frost, carefully melt ice with hair dryer.
If the evaporator coil is solid ice heater or timer or fan has failed. good luck