The inside blower doesn't work if I set the fan switch to the on position or if I turn the air on.it works great with the heat

I suspect the "fan switch" in the thermostat (that's where you try to turn it on, right?) isn't working. It works with heat because a thermal switch kicks in and turns it on.

I believe you need a new thermostat. You can check this out by removing the cover or outer body of the thermostat to get access to where the wires are attached. For complete directions, you'd have to do this and tell me what you see. You can do this yourself if you have confidence in your abilities.

This page shows color codes for most common thermostats:
thermostat wiring color codes

One wire powers the fan. According to the above page, it's a green or sometimes a gray wire.

You need to determine which lug provides 24volts (hopefully your system is 24 volts). I would prefer that you use a voltmeter to make this determination. You take a wire and touch one end to the fan output (green wire) and one end to the 24 volts. If the fan comes on, you know that the switch in the thermostat is "toast" and it's time to replace the thermostat.

Connect R to G

If there is no R, connect Rc to G

Fan should come on. If it does, then the tstat is bad.

With the confusing codes: (Rc and R) or (Rc and Rh) may be found jumped on the tstat.

I put a jumper between the green and red but didn't get any results

Bad information - deleted.

Quote:

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Originally Posted by Perito

Looks like you need a new thermostat. There are some nice ones out there. Consider an automatic setback thermostat. I got one that handles both heating and cooling -- you don't have to switch between the two.

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Perito:

I don't think so. The problem is at the furnace or the wiring to the furnace.

Oops. You're absolutely correct. I think I was asleep at the switch, there. As KeepItSimpleStupid noted, since the fan did NOT come on when you bypassed the thermostat, the thermostat is not suspected. You must look elsewhere for a fix to the problem.