Hello again, there is no need to pay for another diagnosis fee... that diagnosis is established. It is a worn out system that needs to be replaced.
Because of the common walls you have with the other houses your heating and cooling loads are less than is common for a 1500 square foot free standing house. My earlier estimate of a 2 to 2.5 ton system is accurate.
Just call in 3 or 4 of the local HVAC contractors for an estimate to replace the system with a 14 SEER equivalent heat pump, that has a 10 year warranty on the compressor and at least one year part and labor warranty on the rest of the system.
Each contractor will have to arrive and see what he offers that will fit in the space you have.. there is generally no charge for such estimates.
Spartan Plumbing, Heating
and Air Conditioning
XXXXX NW #900, Washington, DC (NNN) NNN-NNNN · spartanman.com
· "This was my second experience with Spartan after trying many different company's" -
If you can be more specific about which side of the city you are on, I can provide a few other
contractors names who hopefully have as good reviews as this one.