Heating unit worked find. But the moment I tried to turn on the AC, it would not come on to even blow hot air

Can you run it in heat again. Does it come on?

Can you put the fan from auto to 'on' and get the indoor blower motor to come on?

I

Thanks for replying... I did try to change it from auto or on and nothing happened. When I get home, I will try to turn on the heat and see what happens..

That's OK it pretty much just eliminates a few things.

Dumb question but you probably made sure batteries are changed if it needs them.

Next to eliminate the thermostat take off the face plate and touch the green and red wires together. Does the fan come on now?

If nothing than you can hook them back up to the thermostat and check for a low voltage fuse in the unit that may be popped. Quick vid on what it may look like.

Low voltage fuse/troubleshooting in air handler from thermal-medics.com - YouTube (http://www.youtube.com/watch?v=yiy_Gxb_9JI)

Ok. At work now, but will try your suggestions the moment I get home.

Also, can you let us know if this is a new thermostat, or an existing one that worked fine before?

This thermostat has been in the house since 2005 when it was built and I moved in. I also tried the heat and it's not coming on now. It was extremely hot so I couldn't cook. Took the kids out to eat. Just getting chance to try suggestions.

Hi
Please check if you have any wire on Rc or not
If you don't have a wire on Rc then put a jumper bteween R and RC because heat is controlled by R and cool and fan is controlled by Rc, if you have a single transformer system you need to have a jumper between R and Rc for the power
As your heat is working fine so check for the jumper between R and Rc
It should work

Hi Seann. That's why I asked if this was a new stat or not. Sounds like they have had this stat for years and it worked fine before. Also, if you re-read all the post, you will see that the heat is no longer working now either. It could still be a stat problem (not likely), but the rc rh jumper is pretty much eliminated at this point.

Not kowing how old your system is or what it is, it's a stab in the dark. Most systems will have a blower speed for heating and one for cooling and with some a speed for blower only. The control board along with the call from the thermostat will decide what speed is needed. What I'm getting at is you may have lost the output on the control board for cooling or just lost a blower call from the thermostat. Not knowing if its gas, resistance heating or heatpump makes it hard to say they all have a different blower control.