Gas and Oil Home Heating Furnaces - Cost Effective Repairs to Central AC

My furnace is a Lennox GHS-120 (80,000 BTU) with a Sears Central Air Conditioning Custom 600. As I reported in an earlier thread, the air conditioner hasn't worked since I moved-in 14 years ago. Now that I am planning on selling the house what is the most cost effective strategy to get everything working again? If the compressor is bad, do I need to replace what is inside the furnace? I would like to be armed with as much information before dealing with any sales reps.

Your opinions are greatly valued. Thanks in advance.

ON COMPLETE REPAIR COSTS OF ENTIRE SYSTEM.MY RULE OF THUMB IS IF IT IS 50% OF A NEW REPLACEMENT,UPGRADE YOUR EQUIPMENT.PDF

In general, it is not cost effective to replace a compressor on a unit the age of yours unless you can do the work yourself. From our previous discussions I don't think this is the case. If and when you replace the condensing unit, replace the A-coil in your furnace so all components match specifications. Also, you will probably find that the condensate pan and drain are corroded/scaley/dirty,etc. Another topic you may have to address is the electrical, if you replace the condensor you will need to add a disconnect by the unit if you do not have one. The disconnect cannot be between the unit and the house, it must be outside the framework of the condensor. The heart of the A/C system is the compressor and when purchasing a new unit if you have a good compressor you should expect a long service life. I personally have had good luck with Copeland, Tecumseh and Bristol compressors. Most of your lower cost condensors will use these compressors (Janitrol, Gibson, Comfortmaker, Heil, etc.) If you plan on selling your house soon, I feel that one of these units would suit you fine.(I am sure that the Lennox, American Standard, Trane, etc. people will not agree.) Another area that can increase the cost of a unit is the SEER rating. This is the a ratio of energy out/energy in. In the Midwest where I live, it is hard to justify a high SEER unit because we use them so little, in contrast, a high efficiency furnace pays for itself in not time. A 10 SEER unit will be the cheapest and the lowest efficiency one that can be sold today in the US. If your A/C usage is low in your area, this might be the best value for you. There are other options on systems that drive up the cost (louvered fins over the coils, pressure switches, expansion valves, alternate refrigerants, etc.) and you must decide what is right for your situation.
If you want more information on a specific area of concern, let me know.

Thanks "dmeyer" for your helpful commments. I am certain that other visitors to the site will appreciate your extensive comments. I found them very helpful.

Now it is decision time!

As I stated 2/26/01 at 5:21 P.M. ,It's time for unit to be replaced.Check out your local HVAC people and the warranties.PDF