Is it a loud banging noise like a hammer to metal? 

Assuming you're just replacing the furnace (aka "air handler), A-coil (evaporator) and condenser (outside part) that seem like a lot.

Once I discovered from a friendly corner conversation that the neighborhood was built during the post-WWII metal shortage and all the sewer pipes were made from clay.

Sell the old metal airplane engine crates for scrap metal.25 miles east of Dallas off 175 there are two acres you can make $100,000 in 6 months.  

You might consider a metal mini-blind (not plastic). 

Make sure the adjuster pays for both layers being removed, your roof metals, roof ventilation, etc..

Because you don't want Zeeco Metals to buy out the 5 houses next door, bulldoze them, and build their new steel plant right next to you.But that's essentially what we're doing. 

Had my HVAC guy set the coil and plumb them.What heating and cooling companies want is crazy.

You want a good solid reading of how cool the air is entering the evaporator coils.

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