heater help: not the usual heater problem
I have a 97 4 cyl TJ with no AC.
The heat is marginal so I did the normal things: flushed the core, changed the thermostat, checked the operation of the diverter, mixture flap etc.
What I noticed is that when the mixture flap (temp control lever) is on full hot, the airflow through the outlets is severely restricted. Almost no air flows at all (what does flow is warm, however) When the temp lever is on cold, the blower moves massive amounts of air, probably triple the amount.
So my feeling is, the OUTSIDE air passage (not the internal pipes where the water flows) of the heater core has become blocked with debris somehow and airflow across it is very limited, thus producing very little heat.
Has anyone ever heard of this and know how to fix it without dismanteling the entire heater box? I was thinking about taping off all the dash outlets but one and blasting air backwards through the system with a backpack leaf blower to try to unblock the core.