heat then no heat

i have a 96 concord 130thousand miles on it my problem is i had heat then it went cold i put new termuastat in not it worked 1 day now cold what is wrong can anybody help

i have a 96 concord 130thousand miles on it my problem is i had heat then it went cold i put new termuastat in not it worked 1 day now cold what is wrong can anybody help

I had the same problem with a 2001 concord. On the 2001 there is a bleeder tap on top of the motor at the front where the radiator hose hooks to the engine. I could never get it to work like the manual so I took a 1/4" clear plastic hose about 4 foot long and slipped it over the the end of this bleeder tap. I made sure the reservoir was full and then loosen the tap. I then sucked on the 1/4" line (with my mouth) until the reservoir was low and no water came out of the bleeder. I repeated this process untill there was nothing but water coming out of the bleeder. Carefull not to get the antifreeze in your mouth. With the clear hose you can watch for this. Once there is nothing but water/antifreeze coming out of the bleeder tighten the bleeder and refill the reservoir. During this time make sure the reservoir doesn't get below the add mark. Also during this time there will be indications of air bubbles coming out of the clear plastic hose. This process should continue untill no air is present. Air causes an air lock in the system and want let water flow freely.