Hi, I am so new to this I'm in diapers, so please forgive my ignorance. I found out by reading other topics in this forum how to check if my a/c was working, and I did get it to come on (outside) by crossing Y and R. The blower (indoor) was working only in the ON position. I couldn't get to the store to get a replacement tstat for a few days and was told by a help desk person that I could leave the two wires (Y and R) together until I could get a new one, and if I wanted to turn the a/c off, I should switch the fan from ON to AUTO. Well, I did that yesterday and when I tried to turn it back on... nothing. The blower won't come on at all. I have checked the fuse box (on the wall in the basement) and all the breakers are in the right position, and the "light" switch on the outside of the furnace is ON. I’ve also tried to cross Y, G and R and I still get nothing. I know I'll probably have to call a pro. but I would still like to know what I'm in for. I was also trying to avoid a pro because my son has autism and freaks out around strangers or anything new, not to mention the expense. All help and suggestions are truly appreciated.

Even though breakers may look on may times they are not. You need to shut completetly off, then back on. Open unit up and if you have a circuit board on it check for a 3 or 5 amp (auto type) fuse in it. I may have blown. If no fuse in it check the low voltage side of transformer for 24 volts.Post back with results.

Reading back over your post you said you replace stat. You do have it wired correctly don't you?

esquire1- Thanks for your quick reply. No, I have not changed the tstat yet. When I said that "I did that yesterday...", I was referring to turning it from ON to AUTO to turn it off because it was getting so cold in the house. Then I tried to turn it back on again later and it wouldn't come back on. Also, I remember when I first crossed Y and R to test the a/c there was a little spark when the wires touched. When I spoke with the help desk they said this was normal. Later when I crossed Y, G and R I didn't notice a spark. I don't know if this means anything, but I just remembered that. I will check the breaker when I get home today, and if you know of any sites with pictures of the circuit boards/fuses/transformers that I could look at to kind of know what to look for that would be great. Thanks again.

What brand do you have ? Maybe I can find a site with photo. I'm thinking you blew the fuse or transformer. Nothing too serious and something you could repair. Hopefully you have a fuse in the board. If not I would advise putting an inline fuse in to protect transformer in future. But first leat's get it up and running

If the light on the furnace is on, the circuit board fuse, transformer, and furnace breaker are OK. If the light isn't on any more, the fuse is the first thing to check.

Shutting the fan off and leaving the compressor on was a very poor idea. It could run until a temperature switch or pressure switch kicked it off. Somewhere inside the outside unit there may be a reset button, often red. Shut the power off at the outside disconnect and open it up, and try to find it.

I will check the brand when I get home and I will also check the for the reset button outside. I never noticed a light on the furnace before, but then again I never really paid that much attention to it because it was working. Thanks again.

I am sorry, I misread your original post, '' "light" switch on the outside of the furnace is ON''. If it is on the incoming power, being lighted just means you have 120 volts in. Often the circuit board has an LED that indicates the circuit board has power from the 24 volt transformer. In case of trouble, it may flash a code.

You already are at a site that has pictures of many furnace parts. I think you already found the sticky for this forum. I wish I had as good of a one in Dogs as Northern Heat has here. So check to see if it has the pictures you need.

To do simple checks like this you do need some tools. A test light, a meter, or a voltage detector might be the best place to start with. I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit. You do not have to open up housings and expose electrical contacts. You are looking at where your hand is, not where the meter is. Most people are capable of doing repairs and will get it going and not get hurt if they use a little sense. The voltage detector makes it even easier.

labman-
O.K. here's my inexperience again... What do you mean when you say "You are looking at where your hand is, not where the meter is."? I really do appreciate all your help. Hope I'm not driving you nuts.

Move the G wire on the thermostat over with the Y that should get you going until you get your new T-stat.

If you are using a meter to check for 24 volts from the transformer, you must hold the probes in contact with what should be hot terminals. So your hands are near the bare, hot terminals, but the meter is often outside on a flat surface. With the voltage detector, you are looking at what you are holding in your hand, and it doesn't need to be near any bare, hot conductors.

Transformers have 4 wires, 2 connecting to the black and white wires from the house, and maybe a red and blue one connecting to the furnace controls. They are the ones that should have 24 volts.

You could rip the old thermostat out and twist the red, green, and yellow together. If the A/C doesn't run inside and out, there is a problem other than the thermostat. Just keep the white and any blue wire away from the red.

Hi again- Just wanted to let you know that everything is working fine. It turned out to be a fuse on the circuit board. I switched that with a new one and got the new tstat installed late last night, but this is the first time I've had to get back on the computer.
Once again, many thanks to all. I guess you never know what you can do until you have to do it, and I couldn't have without help and websites like this.

Angelique