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i replaced my heater core last night and did a drive let the engine heat up so i turned on the heater and gave it sum time so it could heat up. the heater still doesn't work
 

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:stupid
 

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been on the search on the forum looking for a write up all i could find it this, not sure if its what im looking for

http://www.fullsizebronco.com/forum/showthread.php?t=56004&highlight=blend+door+stuck

ive been looking over the threads and what i understand is the door is a cable controlled door that opens and lets the heat flow through the vents the only problem is im not sure what to look for when i take off the cover to the heater core. pics would help.
 

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So I'm having a similar problem with my heater. I just replaced the blower motor and the control switch and now it works, or atleast you can hear it working. There is no air whatsoever coming out of the vents or defrost. Any Suggestions?
 

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Did it work before? I had a '66 F-100 that had an animal nest up in the thing and it really stopped it up.

If not, check to make sure that your control cables are not binding up. Mine were. I think they still may be a little, as I have no "Off," position, but heat and what passes for defrost works.

So I'm having a similar problem with my heater. I just replaced the blower motor and the control switch and now it works, or atleast you can hear it working. There is no air whatsoever coming out of the vents or defrost. Any Suggestions?
 

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Actually I didn't even think about that. It worked half-assed before and only came out of the defrost. There aren't any nests that I can see (i took out the glove box and temp control, etc. Were they in the vents themselves? We went over every single wire and know for a fact everything is 100%. Like i said it's working perfect, but it's just not coming out.
 

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That 66 didnt have much in the way of vents. There was just a bunch of pine needles and fluff that was packed around the fan and filling the bulk of the box under the dash. And it stunk, just for good measure.

It's pretty easy to pull that whole thing to clean it out.

Or you can lay on your back and look up inside the floor vents with a light. Maybe poke at it with a coat hanger...
 

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Nothing comes out when I move the selector. There isn't anything in the box where the blower motor is and like I said there isn't anything I could see when I looked up behind the dashboard and when I had everythign else pulled out
 

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yo,
Chilton Manual for 66 - 81 Bronco, Partial, Scanned Copy; see Chapter 5 Chassis Electrical, much HVAC info
Source: broncocity.com @ http://www.broncocity.com/66_81_manual.htm
See page 186 for Location of Heat/Defrost Crank Arm, Control Cables, etc. Check all for proper op.

and for reference; all by Indybronco (Lula Mae) at SuperMotors.net

Control Panel Parts Diagram, Back View in a 78


Ducts, vac motors, etc





 

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yo, Lost power again...
so since you're still here, instead of editing my prev reply, I'll incl the remainder by Indybronco

Temperature Blend Door Control Cable, Outside Recirculate Air Door Contol Arm, Vent-Heat Control Arm, Temperature Control Cable, Plenum Chamber, Floor Outlet, Right, Left & Center Instrument Panel Outlet, Defroster Control Cable Location Depiction in a 78


and all his other SM diagrams @ http://www.supermotors.net/clubs/superford/registry/1964/33106

Outside Recirculate Door Vacuum Motor (White Vacuum Hose), Air Inlet Duct & Evaporator Box (Case) Location Depiction in a 78 by Indybronco (Lula Mae) at SuperMotors....
 

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yo, ok

Do you have any air flow from registers, defroster ducts or floor registers/outlets? in any setting?

Check vacuum lines; I forget if 78-79 is same as later years where
"...The air handling system is designed to provide defrost when no vacuum is applied to any of the vacuum motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak. Instead, a leak in the vacuum control circuit will send all airflow to the defroster outlets. This condition may occur during acceleration (slow leak), may exist at all times (large leak) and may happen only when certain specific functions are selected, indicating a leak in that portion of the circuit

a vacuum gauge is a great <$ tool
Vacuum Gauge Diagnosis - BEST!; Normal engine; Steady gauge 18"-20" at all speeds..." READ MUCH MORE
Source: by Craig U at http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm

Vacuum Leak Test, Carburetor Models; "...First, use a mechanic's stethoscope (just the hose, no steel probe) to try to localize the leak with the engine running. Check the carb base, body, hoses, or what have you. Turn the engine off, then use a small spray bottle of extra-soapy water to spray the suspected area with a moderate amount of water. Next, find a manifold vacuum port (the brake servo booster hose for example) to apply a small amount of shop air. Apply just enough air pressure to get the soap to bubble. We don't want to ruin any check valves or anything. Seal the carburetor throat(s), then watch for the bubbles. You'll find the precise location of your leak..." Ck under dash behind control panel door vac motors, vac tank in engine bay, etc.
Source: by niehoff.com


AutoParts2020.com - Gas Saver Vacuum Gauge, PM1520, 2 inch; & many parts & accessories
http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=87069

Vacuum Gauge In-Dash pic; "...I have a vacuum gauge mounted right in the dash of my truck. I use it to also help determine the load my engine is under while driving, and to estimate fuel economy..."


Source: by William T at fordf150.net
 

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When I checked I had already put the dash and glove box back in but there was nothing coming out of the defrost or any vents. I also put my hand around the plastic box under the dash that is in fron of the blower motor and stuff. No air there either, or the rubber duct that goes out from the side. The core is getting hot though and like I said the fan definitely works.
 
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