I would not let them put the exchanger in the attic, don't trust the pan/tube/switch. My exchanger is under the house in crawl space. The unit is a heat pump, but it is split. The one in my previous house was one unit that sat outside. Think I like that better than the split unit.
I have a service contract with a local company here, they service it twice a year, they just could not get anyone out here in the dark to try to work on it. Hopefully they can get out early tomorrow and get it going.