ok so the heater core was blowing antifreeze out the vents to i put a new core in there and i can feel the hoses coing into the firewall are hot, and the cover over the heatcore is warm.. but air ocmes out cold.. when i flick the tempratre control from cold to hot, does the same fan operate or does it switch to a different fan for the heater? is it something electronic or mechanical? am i goign to just swap the controls in the dash or something else? any input is accepted and im thankful!!! thanks!
New heater core in '90 Bronco, but no heat?
- Thread starter Xearo69
- Start date
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Seabronc
New member
Do you have A/C? If so, the controls are vacuum controlled and you may have a broken vacuum line into the control. Check the black vacuum line going in on the passenger side, it should go back to the vacuum reserve tank and a check valve, from there to the vacuum tree on the intake manifold. The same blower motor is used for A/C or Heat. With a broken vacuum line the default output is the defroster vents. The Cool / Warm control is a mechanical linkage to a flapper door that determines how much air flows through the heater coils. The attached diagram is for an 83, but very similar to the one in your truck.
Good luck,
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2NDTOUR89
New member
Check to see that your cable is routed correctly and did not come unhooked. I did the same thing with mine and found that I forgot to put the cable back in the same location and it made the cable just flop around and not open the heater door..
good stuff thanks.. now i have something to work with! im about to go try to install my new rear hatch motor (assuming its broken.. mabey a quick continuity check across the coils? i think jumper leads from battery is the easiest idea!)
