Carrier Infinity controller can be sensitive to poor ductwork sizing/design. your dealer needs to address this issue today. document all warnings so they will have this info. keep in mind, for a five ton,you need 2000 CFMs both supply and return. if it's not too uncomfortable and you are certain dealer will be returning today, I would cut system off.

IMO

Time to have the ductwork looked at--could be undersized and need some help. How many returns do you have?

I have three good sized returns feeding back in- one of these was added last
fall as an expert said I wasn't bringing back enough air. That did improve my
cooling performance, but the 5 tons is just a little under what I need on a super-hot day. Today's a good test-- 99 degrees outside and I've crept up to what is now 78 degrees inside, with 48% humidity. So it's still comfortable and we don't get many days this hot in Charlotte. No one has come back yet to look at this, but will in the next day or two-- they feel that maybe some dampers are closed within my ducts. I was told running the system is not a problem (although that's not what tigerdunes felt).

Charlotte, summer design 93 dry bulb, 74 wet bulb near 43%RH. As air is cooled the humidity percentage in the home can, on rare occasions, be higher in the home than the outdoor humidity.

A 1.33" ESP @1750-CFM 350-cfm per/ton, is way too high.

Some air purifiers run the static way up.
Ask them what the pressure drop through the purifier is.

It appears, more duct renovation will be needed.
On 5-Ton systems, it can be difficult to get required airflow at the air handler's ESP rating. - udarrell

Here is a link that might be useful: Sizing of Residential Ductwork Systems

I just had my second Infinity 15 Seer system (2 Ton) put in for my upper floor. When they ran the tests the static pressure indicated was 0.33. I think that's good but how do you tell. Is there an absolute number or is it based on air flow etc.

for axg9504- the way I learned about it was when they connected my Infinity Controller thermostat. It came up with the warning message.

Before you get complicated make sure they don't have some supply grilles closed or something simple like that

Here is a link that might be useful: Air Conditioning Repair made easy

I just had my second Infinity 15 Seer system (2 Ton) put in for my upper floor.
When they ran the tests the static pressure indicated was 0.33". I think that's good but how do you tell.
Is there an absolute number or is it based on air flow, etc.
======================================================
That is a very low & good ESP reading, if taken before the blower & before the evaporator coil.

However, that low an ESP reading could be indicating Supply duct air leaks! It is a suspicious reading, check for duct leaks.

The "correct ESP range" is based on the Blower data figures. - udarrell

Here is a link that might be useful: Air Side of Air Conditioning