I have a Trane forced air furnace which recently has had periods when it blows unheated air. When I looked at the furnace during these periods it shows 2 flashes, which according to the instruction manual is an error code which means: System lockout, retries or recycles exceeded.

I don't understand what this means and what is wrong with the furnace. Why does it blow warm air sometimes and unheated air at other times?

Thanks for your help.

When your furnace is giving a lock out code that usually means it went off on a different fault code 3 times and then locked out. Do you have to reset the power to get it to come back on or does it come back on its self? Odds are if it is going out that many times it is a pressure switch code or thefalme sensor needs cleaned. Try to catch it when it fist stops working and see if there is a different fault to it!