1998 Lumina Heater Not blowing hot air

1998 Lumina Just had thermostat replaced, NO coolant leaks
Heater does not blow hot air
Fan works good
Not just cold air but won't get real warm

If you didn't bleed the system of air after changing the t-stat, you have air in the system causing your no-heat problem.

Thanks
Is there an easy way to bleed the air out

jack up the front of the car so the radiator cap is higher than the engine. Loosen the radiator cap to the first stop. start the car and let it warm up. crack the bleeder valve nearest the t-stat and see if any air bubbles out. close the valve. Next, open the bleeder on the transfer tube. shut the car off, and then immediatly re-start. This will sometimes force the air to the radiator. Check the coolant level in the radiator (not the overflow) and refill if necessary to the radiator neck. Tighten the radiator cap fully, then restart the car and repeat the bleeder valve proceedure. If no air bubbles out, you should be done. Let the car down off the jack and test drive.