Mitubishi hyperheat h2i not heating below 0F, but rated to -13f

Hey there,

Looking for a sanity check - we have two Mitsubishi hyperheat h2i multi-head heat pumps that are about a year old (30k BTU and 24k). They are rated to work down to -13.

Last night the temps were reported as -7 as the lowest, and I woke up this morning to a house in the 50s, and the air handlers recirculating cold air. The outside air temperature was reported as 0 degrees when I woke up. Two hours later, outside air temperature was reported at 5 degrees, and one of the units starting working. An hour later, the second one turned on at 8 or 9 degrees.

I had a tech come out, they confirmed refrigerant levels were normal, the air handlers were getting sufficiently hot, etc. They told me they 'probably shut off' due to sensing it being below operating temperature.

It seems a bit unlikely to me that there was a 20 degree difference between reported air temperatures outside and the temperature of the units. The tech told me with wind chill, the fact it's over a driveway, etc that could explain the difference.

Am I wrong in feeling this isn't a sufficient answer? I was sold units advertised to work close to 20 degrees colder than it was today. I wouldn't have installed these if I knew they would shit the bed at 0F.

Is there anything I can do? They're under warranty. It strikes me as insane that the devices wouldn't have some sort of running log where they indicate when they went into lockout mode, and I just get a 'this is probably what happened' and not 'this is definitely what happened' answer. Is it possible that the installation techs had programmed the units to shut down before -13F? etc.

Thanks!