1997 Ford F150 4.6 Heat Problems
 

Well I just bought this truck and so far its been a pretty good truck, I only paid 950 for the truck, with 240,xxx miles on it, it needed new plugs and wires. It didnt have heat when i bought it, but the guy said it was just a switch for the door, replaced it and nothing. so i checked the heater core hoses and nothing neither one was hot so i flushed to whole system, put all new antifreeze in and still got nothing. i know its starting to get nice out but would like to figure out whats wrong with it before next winter because my stang dont see the snow. if anyone has any ideas or has had this problem let know what you did to fix it thanks.

also there is no pressure in the heater core lines

sounds like somethings clogged in the lines, id take them loose and see if you could get water or air to go through them. sounds like a radiator stop leak clot to me.

If the engine temp gage goes to normal(and no overheat indication) I agree with the plugged line post.You could have a plugged heater core,or it could have been "bypassed" alltogether.:-fire
Problem is,when you buy something from an individual,you never know whats been done to it.......Ive seen some really bizzare things done to a vehicle just to get it sold,and although the heater core bypassed statement seems far fetched,you might want to verify it in indeed connected.If you find its not,dont bother hooking it up...get a replacement....:-X25

like i said before i fushed the whole thing that means taking all hoses off and running water down them including heater core hoses i dont mean to sound rude but its something ive already said

You may not have enough fluid in the system.
Mine goes away from time to time and thats the symptom I get.
You didnt mention your heat guage and the thermostat. Did you check that?

yes i have i just put a theromsat in it last weekend still nothing i thought it might have a valve or something on it so i pulled the big spider looking intake off and nothing back there this is driving me insane, i have another block and heads for it that im rebuilding do to this one has 240,xxx miles on it

You say you flushed water through the heater core?
Did the water go in one side and it came out the other side fairly free flowing? Both directions? That's important. You may have some foreign material in the Heater core system that will allow water to flow one direction and not the other.

If you did that, it leaves the Valve that stops the hot water from going through the Heater?
When you flused the heater, did you flush with the valve closed and open?

Did you verify the engine is heating the fluid and it's circulating? IE: is there fluid going in and out of the plastic overflow jug?

where is the valve

You'll have to look.
When you get the truck running, Cycle the Temp knob a few times and listen for the action.

On the older trucks it was out in the engine compartment somewhere and probably is operated by a Vacuam line. Normally its out in the engine compartment for two reasons.
They some times leak.
And they want to keep all the heat out there instead of in the Cab.

I'm pretty sure that there is no valve controling fluid flow. Coolant runs thru the core full time. Temp is controlled by the blend door. When you say no heat, I assume you mean no warm air in any switch position, vent, defrost, heat, etc...

If that's the case, try swapping the knob from the temp selector and fan. The temp knob is know to crack.

If you're getting warm air from the defrost, but you can't get the airflow to move down to the heat output below the dash, you have either a bad blend door motor or blend door.

That's correct-there is not coolant control valve on the 97-'03 F150's.
JL

if the windshield gets a film like antifreeze and very little heat, gets a slight fog coming out the vents is that heater core replacement time