When we got home unit was a block of ice does it mean I am low on charge. Change filter regulary.also also recently it was 85 out and the unit ran constantly and neve got below 79

Not always the answer,, is indoor fan blowing ? Is it blowing at proper speed? Could the evap-coil be in need of cleaning? The HVAC tech you need to come in to look system over should be able to determine

Let the ice melt, then clean the coil by using a brush attachment on a vacuum. If it freezes again after that, call a tech.

The coil needs to be cleaned from the underside,, the inside of the coil you can`t see until the end plate is removed so you can get to and see,, just vaccuming the outside isn`t getting the job done

For mine I vacuumed the filter-side of the coil. Seems like it would be the dirtiest.

Most of the coils do not need cleaned, if you have a 90% furnace. If the dirt is anywhere it is stuck to the secondary heat ex and the blower will have to be pulled. Most likely you are low on freon.