When a person doesn't know all the components of somthing,it is somtimes prudent asking they not only list what they are replacing but also list any component they will not be replacing that exist on old system(not that replacing all these is nessary in all cases). i e vent cover,duct,condenser pad,t-stat,low voltage wire,high voltage wire,condensate drain pump,condensate drain lines,disconnects,breakers,gas line. I would also want stated in contract "meets all code requirments".
How long ago and what was wrong with work done by GC?
Have you been compinsated?

This post was edited by klem1 on Fri, Jun 14, 13 at 5:43

At a minimum you need to see the following:

- Perform a heating and cooling load analysis
- Model numbers of all equipment
- AHRI number for legal matches
- description of all work to be done (line set, duct work, vents, returns, electrical, plumbing, etc.)
- type of thermostats, filter, condensate pumps, humidifier, condenser pads, etc.
- warranty information for parts and labor
- who will pay for permits and guarantee all work to be done to code
- when will payments be due and any applicable rebates

I think you have gotten a good education from the contractors who have looked at what has already been done. If you know of specific things that need to be fixed then list them as items in the SOW (Statement of Work). At this point don't assume anything and don't rely on the contractor verbally agreeing to anything.

Good luck.