Not getting 24 volts to condenser

SOURCE: we installed a 4 ton

you have a missmatched system, for it to work try removing the orfice on the high side txv it is not allowing the evaperator coil to fill with refrigerant properly coleman and intertherm dont like each other since they control a large market in the manufactured housing heating and cooling units electricaly connecting the componets together no issue prefromance sometimes is the issue hope this helps

SOURCE: Carrier air handler tonnage?

That is a fairly large difference. It is usually ok to have the inside evap. coil and blower up to 1 ton larger than the outside condenser. That will make the unit slightly more efficient as well as less likely to freeze up on low airflow situations. It is not recommended to install a new condenser on an old evap coil. There has been a lot of changes to the design of the coils in the last little while. For example a 10 year old 2 ton coil may only have 3 cubic feet of volume but a new 2 ton coil may have 4 cubit feet of volume.

There are many factors that may have infulenced the decision on what size condenser to install. Many of which can only be done by visiting the home and doing alot of work, checking the duct sizing bioth supply and return, inspecting the insulation and windows of the home etc. etc. Most of the time that never gets done. You can blame the contractor for not doing a complete check, but at the same time you can blame the customer because many contractors that are that good loose the job to a cheaper bid that did not no any of the research. It is a catch 22 for everyone involved.

There is ALOT more to sizing equipment that many people think, sadly that also includes many HVAC contractors. Way too many people use "rule of thumbs" or flat out "guess".

Sorry for the rant but your queston can only be answered by a good well educated HVAC contractor visiting your home. That type of a contractor is getting hard to find these days in such a price competetive world.

SOURCE: Rheem Air Handler will not run

We tried to bypass at the Tstat. Thanks for your time and interest.

SOURCE: Can Air Handler !1/2 ton run with 2 ton

Its done all the time. It is sometimes better to do this because you run a colder coil and rmoves more humidity. The newer unit have variable speed fan and run slower to do the same thing. Remember the lower the humidity the higher you can raise your tsta. Example In arizona at 95 degrees you dont feel the heat as much because of the lower humidity. Its ok to do so. You get more btus out of your unit that way. Rus. I have dozens of units with air handlers 1/2 ton smaller...

SOURCE: 3 ton condensor and 2.5 air handler

I hate to use rules of thumb but 500sqft per ton depending on your windows and insulation. you are probably ok with a 2.5 ton however it will not work with a 3 ton outdoor unit as you have figured out. depending on how long that ac has been in you may want to replace it with a 2.5 ton due to the damage to the compressor valves because of the mis match. or if the indoor is newer and the original system may have been a 3 ton then i would replace the A/H. and be prepared to replace the outdoor if the valves are to far gone. If the trane is a new high effiency 2 and the goodman is just a 10 SEER you may be able to have a txv installed on the trane unit and a kickstart device outside. but only if its a high effiency but their again if the A/C fails you couldnt have a high effiency 3 ton you would have to drop down to 2.5,