Here is the scenario:

House is 13 years old with Trane XL 14i central heat/air unit.

We have lived in the house for 7 months and a/c worked fine and heat worked great until last night.

With the system turned to auto and set to 69, the fan blows nothing but cold air and the house will not warm above 56 degrees. I must admit I checked the air filter and it was horribly dirty, I admit I dropped the ball and haven't changed it in the 7 months.

So, the system is not coming on at all outside- only the fan inside.

Could I have damaged the system by running it so long without changing the air filter?

What would you suggest I try to do prior to calling service?

THanks.

First check the power source. Then check your control panel. Normaly there are 2 motors on heating and air. One out side on the unit and the outhwer is a blower unit inside the house. Becarful thouw ac ar 220v 60hz. It can kill! Check the motor copacitor. Be carfull. Discharge it properly then use a multimeder to check the cap. It should go down tord being closed then should read open. Is it gas or electrick. If it is electrick it normaly has heating elements lick a stove. But if the out side fane is not turning on it is probably the cap. Or the motor.