GMC C3500 HEATER NOT WORKING

I Have Weak Heat In A 84 Gmc. I Have Replaced The Heater Core And Thermostat, The Supply Hose From The Core Is Hot, The Return Hose From...

Heater Problem 1993 Gmc C3500 V8 Four Wheel Drive Automatic Winter Is Comming Up And After Freezing Last Winter I Want To Be Warm. My...

Number 5 On The Heater Control Doesn't Work. One Through Four Works Fine As Do All The Other Features. I Used A Test Light On The Electrical...