No heat and I think I've tried everything...

[jonrbrt]

I thought the same thing... simple... but I've actually given up on this. This is a repeat from earlier but I still cant believe I cant get this to work. The heater hose was hot on both sides of the heater control valve, but no heat so I decided what I thought was hot maybe wasnt enough so I by passed the heater control valve. still no heat! I removed hoses from heater core and simply used my garden hose to flush through. It appeared to me it was coming out as fast as it went in--so core is not plugged or restricted. Still no heat. I've had the inside duct work apart at the plastic "S" I can see the core and it feels hot. there is no mouse nest, no leaves... all flaps inside the truck move freely. While in the garage after the truck warms up I have heat it doesnt seem as hot as it should be but its warm air. As soon as the truck starts moving say 20 mph --no trace of heat. It must be a vent issue. I replaced the defrost last fall. but I have verified vents are working as they should and the routing on vacuum hoses is correct. The vent in the passenger kick panel never opens--it must be stuck closed--for winter that's good. I think it's the vent under the cowl---it seemed to be in the up position--and not moving. I unhooked it--I'm not sure it's closing all the way??? How does the cowl come off? Do you have to remove the fenders to get to screws on the sides? I'm thinking it may not be closing all the way. I can tell it's still attached to the linkage because I can move it but I can't tell and dont think it is going all the way down (towards the ground) I assume this would be the closed position.
Thanks for any ideas....