Gas and Oil Home Heating Furnaces - AC Snow in furnace

I have a heat pump and the blower housing contains an inverted V shape coil (coil?) that has many corrogated bands of metal. This has snow on it. Heat pump is new, supposed to be compatable, coil is 4-6 years old.
Happens to be the big holiday this weekend and it's definately a hot one in my house. Needless to say, AC guys are on holiday, too.
What is causing the frost?

to eswan's thread.PDF

the item you are refering to is the inside coil (evaporator). It is too cold. The probable causes are low airflow or low refrigerant or both. Open all registers, remove and replace all filters, clean the coil of there is a lot of gunk on it (cat hair for example) Dont cut yourself the fins are sharp. keep the AC off and turn on only the fan. Is there are really good flow or air out all the registers?
Turn on the ac.

Good luck.

Once the frost is gone from the coil, and the refrigerant is balanced again, do this.

Turn on your A/C, and let it balance. (About 10-15 minutes should do it)

First, feel the air coming out of the vents. If it is very cold, then it is likely that your airflow is too low.

Keep the unit running, go to the condenser(outdoor unit) and feel the suction line if there is any exposed part without insulation. (Thicker pipe) The line should be cold. If it's cool, than it is likely that your system is low on refrigerant.

Also, while the unit is running, feel the liquid line (thin, not insulated) at the condener. That line should be warmish if it's not that hot out (i.e 73F outdoor) or very warm if it's hot outside. (i.e 87F). If it is very hot when it is hot outside, or very warm when it is a little warm outside, then your system is low on refrigerant.

Very warm air coming out of the condenser is also an indication of lack of refrigerant.

Hope this helps.