I have a central AC unit that is old but still cools very well. I would guess it dates from the mid to late 70's. I want to keep this one in service a bit longer for reasons on which I will not elaborate. I am not sure of the manufacturer but I can provide information from the service plate if need be. Late last summer it became hesitant to start. I could hear, outside, the contactor closing and opening several times and finally the compressor and fan would start, run for less than a minute and stop. After a short interval it would repeat this. After three or four attempts it would start, run and cool. I shut off the power and had a look at the unit. I took some pix, drew my own wiring diagram because the old one had been used as a mouse nest and disconnected the few devices that were easily removable. They were two run capacitors and the contactor. I replaced these items with new from a local HVAC supply. But now the AC would not even try to start when I turned it on at the thermostat/control. Back outside I smelled something burning. Power off. I realized the 240v-24v transformer was overheating. Back at the supply house I got another multi purpose transformer. Like a fool I wired the new transformer incorrectly. I bought another transformer. It is a White-Rodgers 90-T60C3. I got this because it has an integral circuit breaker. This time I made sure to use the 240v and common wires. Still, no start. The integral circuit breaker tripped. With the control circuit off and power to the unit on I am able to start the compressor and fan by manually closing the contactor. So I know they work. Inside the house, I can also close the relay for the furnace fan manually and it runs. So I know it works. That leaves the control circuit. The control unit itself is also quite old. It's analogue, has the Kenmore brand name and it is only used for the AC as I have hot water heating with separate controls. I also happen to have a newer Honeywell control which I believe will work for this purpose. But I first need to determine what is the problem with the control circuit. Is it the control wiring? The control itself? The relay coil at the furnace? How do I check these things? I have checked the outside unit with the multi meter and it's reading in the 220v-240v range. Likewise, the transformer is providing 26.3v which is within the operating range of the old control unit. That's all I know at the moment. Any advice is greatly appreciated.

Hey guys, my wife and I recently got a new system installed in our home and we got a few quotes and decided on a company that we deemed reputable. A guy came out and said we currently have a 4 ton unit and said we needed another 4 ton unit. I was not aware until after the install and researching symptoms that a manual J is needed for the dealer to install proper size. I think the guy just saw we had a 4 ton and put in a 4 ton. I now have a brand new Lennox system 15 seer 4 ton that "short cycles" it comes on and runs for 10 minutes or even under 10 minutes, then turns off for around 10 minutes and so on. Now my humidity is 52-55% and the house feels clammy whenever the AC turns off. Is there anything that can be done? Should I insist on the dealer running a manual J now or is it too late? Am I screwed? If I keep on them will they take out this unit that is too big and put in the proper size? Something is wrong and I am not happy. Any advice please help. I feel it is the contractors job to install the proper sized unit, am I wrong? I am in San Antonio, TX