Progress Thread 66 289 Auto Notchback No Heat

Jun 4, 2016
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#1
I have a 66 notch 289 auto with a new radiator, heater core, thermostat ,and all the hoses in between. the heater box itself is pretty fubar though. The problem is no heat, it blows cool air and I know the way 66 works is that its a constant flow and no valve like in the next body style. I forgot to mention the hoses get hot when routed either way. Hopefully someone answers this because the forum looks dead.
 
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rbohm

SN Certified Technician
Apr 12, 2002
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#2
do both hoses get hot? if so then you have an issue with the doors in the heater box itself. its easy enough to pull the box and tear it down, lube up the door hinges, replace the foam seals, etc. replace the heater core while you are there as they can plug up or leak, or both. be careful pulling the box apart as it is fiberglass and can break easily. get yourself a fiberglass outlet as well, the stock one if just cardboard and usually falls apart easily. you can find the plastic plenum chamber here;

http://www.nationalpartsdepot.com/f...nal_link&utm_campaign=Mustang_1965_1973#p=236

along with any heater parts you need, including repro cases in case you break yours.
 

horse sence

That $5 hooker turn out to be a guy
Mod Dude
Nov 29, 1999
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#3
If the core is pluged ,one hose into the box will probably be hot and the other not as hot or even cold . The cables to the doors on the box somtimes come off ,some times the shaft the cables attach to spin in the doors in the box ,you will see the shaft move when you work the cables but the doors will not open
 

rbohm

SN Certified Technician
Apr 12, 2002
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#4
If the core is pluged ,one hose into the box will probably be hot and the other not as hot or even cold . The cables to the doors on the box somtimes come off ,some times the shaft the cables attach to spin in the doors in the box ,you will see the shaft move when you work the cables but the doors will not open
the only issue i see here is dealing with a plugged core. if the core is completely plugged, then you are right, one hose hot, the other cold. but the core can be something like 95% plugged, and both hoses are hot, and still no heat.
 
Jan 12, 2018
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#7
Agree with all the above. Did you check the thermostat before you put it in, they are sometimes defective when new. Just a thought...
 
Jun 4, 2016
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#8
Agree with all the above. Did you check the thermostat before you put it in, they are sometimes defective when new. Just a thought...
No I didn't think to check that,wouldnt the car over heat though?
 
Jun 4, 2016
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#9
the heater box was pretty rough,we used epoxy to seal around a couple edges because a couple of the places where the clips lock onto where messed up. All the wires move,so maybe they aren't moving the blend doors?
 
Jan 12, 2018
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#10
Possibly, could be stuck open. How about the resistor, they tend to go out as well. Gotta watch if you replace it, those plastic pins are a bugger to get out. Use a small metal pick or the something that'll push the center plastic pin out. They're hard to find for replacement, usually wind up using a small screw and nut to fasten the resistor back on the box.
 
Jun 4, 2016
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#12
Possibly, could be stuck open. How about the resistor, they tend to go out as well. Gotta watch if you replace it, those plastic pins are a bugger to get out. Use a small metal pick or the something that'll push the center plastic pin out. They're hard to find for replacement, usually wind up using a small screw and nut to fasten the resistor back on the box.
Doesn't the resistor only control the blower motor? The fan blows because I feel air coming out of the vent and when you turn the fan on it squeaks for a second.
 

WORTH

15 Year Member
Nov 18, 2002
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#13
Your getting a bit of misinformation. You are correct it is NOT an electrical issue. If both the heater hoses are about the same temp then you have an issue inside the box or with the temp cable. The fresh air enters the heater box and is directed either threw the heater core or around the heater core. The temp cable is connected to a blend air door that steers the air. It is also important that air can not go by the core because of missing foam insulation. It doesn't take a lot of cold air to ruin the temp output. So more than likely you have a blend door issue, you need to pull the box out of the car and verify the doors all work properly, and that the core has no air leaks around it. Also while it is out jump the blower to power and feel the air flow. On rare occasions I have seen blowers that either turn the wrong way, or have the wrong blower wheel on them and move very little air. You should get a real heavy flow of air.
 

HedTech

New Member
Nov 7, 2017
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#14
Remove the glove box and check the blend doors for operation.
 
Jan 12, 2018
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#15
Doesn't the resistor only control the blower motor? The fan blows because I feel air coming out of the vent and when you turn the fan on it squeaks for a second.
Yes, sorry didn't mean to misinform you. Don't know what I was thinking, maybe the blower wiring or something. It may be better to try and get another heater box instead of spending all that time on one that is that far gone.
 
Jun 4, 2016
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#16
Yeah I was thinking just get a new box that comes with everything. No point in wasting time trying to fix a box that is toast.
 

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