Just black flushed a heater core on a 95 civic ex, (1.6 vtech) bled the cooling system and everything after for about 30mins and had heat right away, for about an hour i had heat then going down the road i started blowing cold air again. Got home let it cool off and checked radiator and still had coolant.

Dont know where to turn to next,
Anyone give me a list of things to check/look at?

Thanks!

 

Is the engine staying at normal temperature? Is the cable on the water valve hooked up and keeping it open? When you flushed the heater core, did you get plenty of flow? It should be able to flow the full output of a garden hose with little resistance.

 

Its always stayed just below normal operating temp mever over heated above half (going up a steep hill once got it a little warmer then normal), i checked the cable when i back flushed and its connected, i even moved the switch back and forth with ease.
When i back flushed i had little to no resistance and was able push put as much was going in.
Just replaced all hoses due to basic maintenance. And also checked thermostat which is good. I just tried again this morning and some heat was produced for about 15 mins then it started cooling off again while the car was at optemp. I could heat the cooling system cycle although.