I have an older Lennox central air/heat system. It worked fine in the summer in AC mode. Now in Heat mode, the condenser is icing up with the outside temperature at around 50F.
The filter is 2 months old so I'll probably replace it to see if that makes a difference. I haven't checked the evaporative coils yet, it's in the attic. Any suggestions would be greatly appreciated.

Is this a heat pump? Lennox has a lot of different systems, do you have a model number?

All I know is it's a central ac system. Don't think it's a heat pump. I'll get a model number later when I can. Thanks