Hi. I had a R410 HVAC system installed last summer. Everything was replaced (outside unit, furnace, lines, thermostat, etc). This summer on the first hot day, I turned on my system and it wasn't cooling. I called the installer back and he said that the R410 charge was slightly low causing the problem. I was ocncerned about a leak, but he mentioned that R410 systems work differently than older R22 that I'm used to. IN older systems, if the charge was low, it would still cool, just not as well. He said in new R410 systems, there is no gray area and that if the charge is even slightly low, the system won't cool. It is not a gradual deterioration of cooling as the charge drops. He will be back in a few days to add more R410. He offered to show me the charge when he hooks up the equipment to there is charge and that only a little additional is needed. Problem is, I'm no HVAC guy, I won't know what I'm looking at if he shows me meters and guages.

Is the information I'm getting correct? Should I be more concerned about a leak in the system somewhere?

If it worked OK last summer but not this summer you probably have a leak somewhere. Use common sense. How could the unit work last summer and not this summer? The unit leaked refrigerant out of the system during the winter when the unit was not in use. This is my opinion from 1000 or more miles away. Get them to FIND the LEAK. Then FIX the LEAK. Then recharge properly. If the unit ran completely out of refrigerant then a new refrigerant drier and a proper vacuum is in order since R-410A mixed with the oil used in the system does like to absorb water when exposed to the atmosphere. This can be a very serious problem if not corrected properly. When the guy shows up also ask to see his EPA card. I am always proud to show mine.