My 88k5 heat is like not working at all i did all the basic checks for anti freeze and stuff like that but it just blows cool air out even if the trucks been running for a few mins it still doesnt warm up anyone know anything else i could do to fix?

 

does the truck to operating temp. if not replace the thermostat. if it does then flush your heater core

 

yeah if thermostat is stuck open it prevents the antifreeze from staying in the engine long enough to warm up.

 

I just went through that problem on my 88. The thermostat could be bad, use the 195 degree one.
You can also check the heater door just inside the firewall behind the blower. You can remove the glove box and check and see if the cable for the heat is moving the lever for the door.
The other thing to check is to see if the door is slipping on the bar itself. If it is it will not open enough to allow the air to flow. It happened to mine and we had to spot weld the door to the shaft, heater is working alot better now.