i have a 94 k2500 4x4 having heater problems ,, nead help

Going to need to provide a bit more information. Is it not getting hot, is the blower not turning on.

The control display is flashing arrows from the cold side to the hot side, ac works heater does not. I have replaced the ac/heater control for the cost of 750.00 still get the same results.

Check your grounds. Also check to make sure your air mix actuator is working. I can't say for sure on your truck, but it should be under the dash. It'* the flap that directs the hot and cold air. If it'* stuck in cold, that is what you will have.