I have a 1993 chevy C1500 hat I can’t get the heater to work. It seems that there is no coolant flow through the heater core. I can take both hoses off the heater core with the heat on and there is no low out of either hose. Isn’t the hose that comes off the rear of the intake the inlet hose for the core. If i’m right, then there should be a constant flow of coolant through the core. There is zero flow coming out of the manifold. Please help!!

 

So with both hoses off core at firewall and motor on, no coolant flow from either hose from block?

 

there is no flow out of either hose could it be clogged up at the intake where the heater hose goes into it?

 

If you have both hoses hooked to the motor AND unhooked from the firewall you should get coolant flow out of one of them with motor running.
With both unhooked at the firewall (motor off now) try holding a garden hose on one of the firewall ports, turn water on low so not too much pressure on your core; should go thru core and out the other open port.
On my 93 suburban, one hose comes off top of back of the intake manifold - hot coolant flows from there to core; other hose returns to top of radiator on passenger side.

 

Hi. My name is Wil. Did you ever get it fixed and if so, how??? I've been having the same problem with my 93 silverado with a 5.7 Lt.