Infinity Certified ? That is your question for the Carrrier man.
Sorry you are having so many problems but as long as the manufactures keep building these expensive toys the more problems the end user will have.
The overall cost of operation including repair especially when it goes out of warrenty will never be recovered. While they are nice units I will never own one and I talk people out of them all the time. There is just not enough trained people with the proper tools to work on them and the price of the parts is outrageous.
You can take a standard high efficiency Goodman unit and add one cheap modification and be within 1% of the efficiency of a Infinity unit. That is $ 1.00 per hundred less savings on gas. If you are a big spender and use $ 2000.00 worth of gas per year you will only use $20.00 more in gas by using the Goodman or other manufactures setup but you will save thousands in maintaince costs over the life of the furnace. While the Infinity is a good system it just does not make sense to a logical person.
A side note from a email one of my students who has now been in the field for 3 years sent me a few weeks ago. Just for fun you might look into the circuit board problems. It might effect the Infinity you have also.
Hi, Mr XXXXXXX
~10 year old furnace started intermittent lock up with error code 31.
Careful investigation revealed intermittent inducer motor. It starts
but stops running or it won't start when heat is called for.
Took the control board out(XXXXXXX) and went through it. The problem found was cracked solder joint on two high Wattage resistors R34 and R33
(both 330 Ohms) had cracked solder joints on the PCB due to heat(?).
Reinforced the joints with silver solder. Now furnace is behaving normal again.
You taught me well.
Timmo