To be clear I did NOT say that they INSTALLLED the $30 thermostat for $200. I said they sold me a $30 thermostat for $200! The INSTALLATION and the SERVICE CALL were TOTALLY different charges so the whole thing was about $600 (and it conked out 3 days later so changing the thermostat didn't fix the problem,and so much for thier "diagnosis") so I DO think that the people I dealt with were thieves. I find it interesting that you would jump to such an erroneous conclusion as to me being difficult being the problem. That was REAL helpful. What I had hoped for was somewhere to start educating myself about what to look for in a good central air conditioner and what factors make one better than another, and if there ARE any REAL hazards about one kind of system over another (although I find that unlikely in refridgeration but I don't know which is why I'm asking). Otherwise the NEXT few people I deal with may try to convince me that System X will explode,and that is why Sytem Y which THEY install is better. Thanks

keep the linesets and coil (the inside part) if the coil has plenty of copper in it. I took my lineset and coil and got around $100 for it. The copper tubing is light and bends easily, I only had to remove the rubber/foam insulation from it. I didn't bother to take apart the coil but they gave me the $ for it. If you have a scrap place nearby it is REALLY easy. I did not bother with the outdoor part though I know there is value in there as well. Mine was a 17 year old Lennox. I found a close place with a decent price https://iscrapapp.com/ Not eery place lists prices online, but you can easily call. The scrap copper price in my area has come down about 40 cents/lb since I did it in during the winter. If your lineset is short then it might not matter. Mine went all the way across my basement, 35 feet?

yes you can add air to your furnace. Most coils are made to blow through, so make sure you install the right coil. Once you find out what size air you need, you have to make sure your furnace blower and ducts are sized to handle that amount of air con. Most heating guys will say you need to move about 400 cfm of air per ton of cooling. Also make sure you have a filter large enough to handle the amount of air you have to move. About 300 cfm per 1 sq. ft. of filter. Best was is to call a pro. to check out your system and price it for you. A lot of times you have to do enough remodel tat this would be a good time to change furnace out, for better eff. on both heating and cooling. Later paulbm

"He had the same conclusion as yours says it is short cycling due to leaking of freon." I did not say the short cycling could be due to a freon leak. I did say it could be due the condenser being increased in size. I don't understand how a loss of freon could cause a condenser to short cycle. Perhaps you misunderstood what the contractor said. But if he made that statement then my confidence in his ability continues to go down. What exactly was replaced? So far I know it was the condenser. I hope he replaced the coil in the attic. Was the furnace also replaced? What about the line set (the copper tubing running from the attic to the condenser outside}? Normally on an attic installation that is not replaced since it is running inside walls. The old line set can be reused but it must be flushed out properly. You can't mix the old and new refrigerants. But, if the condenser was increased in size, the line set may be too small (diameter) to work properly. This is another reason not to be increasing the size of the condenser. Has the contractor returned yet? If there were air flow problems while running the AC, then there will be air flow problems with the furnace. Those have to be fixed. Make sure the air flow works well in the spare bedroom. Just because you rarely use it does not mean it should not heat and cool properly. All bedroom vents should have approximately equal air flow. This should not be too difficult with the furnace installed in the attic.