87 econoline,302/auto, with AC, AC & heat control panel in dash not contigent to one another,i.e. AC not on when heating as in newer cars.
Problem. Replaced a leaking heater core. Before replacement the core did heat very well. Replaced the core with exact replacement. Less than luke warm air. The inlet and outlet heater hoses hot. Removed the hoses at the manifold and the pump and not clogged and water pumps out of the manifold fine.Water flows through the core fine. All heater controls work. I removed the vacuum operated heater valve and replaced with a coupling eliminating the valve. Same result,, very little heat.
The only thing I see that may reduce or transfer the "flow" of more water to the core is the "tee" in the pump line over to the fuel injection block. Dont no what controls the diverting of the flow throuigh the F.I. block, if has a control at all?
Could the % of antifreeze/coolant be too much to not allow transfer heat from the core?
The heating was working fine with the old core(had pin hole leak).
Baffled.
Thanks

 

I replaced the heater core on my 93 bronco and my heater suddenly quit working. After taking a look, I noticed that the heater control works with the braided cable surrounded by an outer rubber or plastic type casing like a bicycle handle brake. There was a plastic piece that holds the outer cable in place so that the inner cable will move inside seperately from the outer. It sounds like this may be the case in your situatuion.