Hi, my problem is a little complex. My unit turns on/off not only when I have it in the "Off and Auto" position but also when it is disconnected from the thermostat.

When it turns on its own it only blows cold air(room temperature) and I can't shut it off so I have to wait until it does on its own, sometimes taking 10 min or longer. There is really no pattern to follow as it sometimes turns on/off hours apart from the last time. I had a guy come out and he originally said that everything looked good but that he thought that the problem was my thermostat since he thought the one I had was a "cheap one". It is a "right temp brand" and I told him that I did not think that was it because I had just bought the unit a day ago in replacement of my original right temp brand thermostat, thinking that it could be a thermostat problem and that I thought that it would be too much coincidence that both right temp thermostats came defective, not to mention that the original right temp that I bought I had 2 yrs with no issues.

Since the furnace was not malfunctioning when he was at my house he suggested that when the unit turned on its own again to go to my thermostat and release the red cable so that we can know for sure if it is a thermostat problem or a furnace problem. He also suggested that when this happened again that I go look at the furnace and see how many times my "red light" blinks so that we can have something to go by. Well it happened about 2 hours after he left and I disconnected the "red" cable on the thermostat and the unit did not shut off. I happened again some hours later with the "red cable" in the thermostat disconnected. I went to the unit and the "red light" inside blinked 5 times on separate occasions. 5 blinks means "sticking gas valve", but when I called the guy that came out he said that he was not sure that was the problem because that did not explain why its turning on/off even when the "red cable" was disconnected from the thermostat, thus; he now thinks that it will be a control panel/mother board problem.

Sorry for the long question but I'm not sure if I am being taken for or what kind of issue this may be. Thanks in advance for your help and guidance.

-Raul

A couple things come to mind that may solve the problem before you go paying for any board. First is the location of the unit if it is in the attic it could be the fan limit switch. It may need to be set at a higher kick in temp. If it is set at say 80 degrees and the attic is 80 degrees it will turn on the blower. So set it to 110f to 120f. Here is a video you can watch and do it yourself. Also I have seen t-stat wires shorted out from things like rodents, dogs chewing on them and nails from people putting pictures on the walls. This can and has happened. The best way to check it is take t-stat wire off at the furnace and see if it still runs. If so it is not the t-stat wires. OK. Well I hope this helps. I accept pay pal tips.
http://www.youtube.com/watch?v=G3NRGhR0O8A&feature=related