Lynn, Your right, its boiling all the way to the condenser.
If the furnace is 2 years old, did the a/c work last summer.
If so, then what changed, coil might be just dirty enough to cause this. Since it was already low on air flow, it won't take much.
If its the first a/c season for this set up. Get the 3 ton blower out of your hip pocket and install it.
Some manufacturers use 1 size blower housings for 2 or 3 different drives, just the wheel, and motor are different, check to see if thats the case with this furnace, and you might be able to change just the wheel and motor.
It was the bosses gig. BL (Before Lynn) I guess they had some noise issues so a smaller drive and some duct work change. When the CU craps out they will get a 2 ton unit.
A three ton condensor on a two A/H...good luck..
If you can verify the load (airflow and temps) to be correct, and you feel as though you are near the correct system charge, then you have a restricted suction line. Either an oil trap, kink, undersized or something. If the evap is frozen solid you could theoreticly be boiling off in the suction line.
Your suction line should never drop more than a couple degrees from inside to out.
Not my deal anymore. Boss man "explained" it to me. I put a frost stat on the suction line at the evaporator because I didn't want it to ice in the attic drip on the ceiling when it thawed.