S13 No Heat, not Thermostat

[CJH]

I recently bought an 92 S13. I am not new to these cars, but I am perplexed. The heat isn't working quickly, and I am from WI. Not cool.

The car didn't heat up at all, so I replaced the thermostat. Now the engine heats up like it should, but still heat doesn't come out of the vents. After about 10-15min, the temp gauge tells me the engine is warm and my thermostat opened up. It takes about 30min of driving for heat to actually come out of the vents. Oddly enough even after 30min, the heat sometimes stops blowing and only cold air comes out.

I know how the heat system works in these cars, and that's why I'm confused. The only thing I can think of is if there could possibly be a clog in my hose from the engine to the heater core that passes through the fire wall. Other than that, I don't have any other ideas.

[PercieBlaze]

check your water pump.

[CJH]

Coolant is flowing, and I'm not over heating.

[sx moneypit]

Are you sure you got all of the air out of the cooling system?