Our programmable thermostat died and we bought a new one this winter. Trying to use our central AC for the first time now and the fan comes on, but the AC unit itself doesn't kick in. We bought another thermostat thinking that might help... but same issue exists. Any thoughts?

If you are sure it (tstat) was installed correctly,check your breakers for the a/c,unit is there power at the a/c? High voltage(220-230volts) and low voltage (24-28 volts),even if experanced electric is dangerous,may be time to call out the experts,, in the cooling mode,is the fan blowing in your airhandler?

After checking the breakers, check to see if the AC unit is frozen up... and then take a look at your air filter. This happens a lot when the air filter is filthy... clogs up the AC and then everything shuts down.

Not a crisis if this is the case.

The AC unit needs to just "defrost" - and you need to replace the air filter.

Remember- you will need a jumper wire from RC to RH on the thermostat.