heater issues

my 93 z-28 has no heat but the car is warm, sumtimes the heat will work but not with the fan on high

Flush the heater core.

I flushed the heater core with sum prestone 10 min flush

Take the heater hoses off the water pump and blow some air through them, both directions. You'd be suprised what will come out.

Keith...

I'll try that tomorrow thanks any other suggestion

Take the heater hoses off the water pump and blow some air through them, both directions. You'd be suprised what will come out.

Keith...

I did the same thing and it looked like something had set up camp and was living in there (?) it worked good after that

i blew air threw the heater core and it still wont produce heat

Flush it and the hoses with water.

If flushing doesn't work, Autozone sells a replacement heater for around $50 with a 90 day warranty. They have a $90 dollar heater with a lifetime warranty as well.

Have you exposed the heater core behind the glovebox and felt it to see if it's getting hot or not? If it's hot, could be something else.