Chevrolet Repair: 1998 Chvey Blazer heater not working, automatic temperature control, upper radiator hose

Question
Last week I turned on my heat for the first time this season and it never would heat up.  this blazer has the 4.3 L v-6 with automatic temperature control--doesn't seem to be any vacuum hoses  only electronics.  I am setting it to manual and turning the temp all the way up.  I changed the thermastat -- no improvement. Radiator fluid seems full enough.  when I touch the heater hoses going through the fire-wall they are not hot -- tells me nothing flowing through.  What's next?

Answer
Hi David, The heater core is plugged up. The passage ways in the core are very small and plug up from dirty coolant. Remove the heater hoses from the engine, not the core as you might make the core leak. Run water from your garden hose through the hose that went to the waterpump first. After you get a good flow go back and forth between both hoses with the water. This will clean out the core.

To keep the core clean you will need to flush the cooling system out. If you don't, it will plug again. I like to remove the thermostat to flush out the radiator and block.
Remove the thermostat and run water into the upper radiator hose, this will push water out the top of the intake manifold and your getting a good flow through the radiator.

Hope this helps

Have a Great Day         Mark