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66-96 Ford Broncos - Early & Full Size
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rust bucket 86

no floor heat or defrost

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My heat works fine. When I put the register to defrost it still blows out the dash. When I put the register to floor it still blows out the dash.I have a blow up of a 80-96 heater core which shows two vacuum motors; the defrost/ floor vacuum motor, and the defrost/ dash vacuum motor. How do i get access to the defrost/ floor motor? If I move it manually and it works my problem is a bad motor if I have a good vacuum supply correct? Sorry for the wording just trying to be complete.Any suggestions would be appreciated, thank you.

Edited by rust bucket 86

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The dash defrost is the default position on a vacuum controlled system. If you are sure that vacuum to the control is good, the control itself could be bad. I doubt that all the vacuum motors aer bad. What year truck and do you have A/C?

 

Good luck,

 

:)>-

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The dash defrost is the default position on a vacuum controlled system. If you are sure that vacuum to the control is good, the control itself could be bad. I doubt that all the vacuum motors aer bad. What year truck and do you have A/C?

 

Good luck,

 

:)>-

I have an 86 bronco and yes it has a/c.

 

UPDATE. It seems all the vacuum motors are working....... I can visually see the rods moving in and out.The problem still exists. The heat only blows out of the dash vents and I do not think it is real strong, yes the blower motor has low, medium and high. Thanks for the reply.......

Edited by rust bucket 86

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yo,

 

"...The air handling system is designed to provide defrost when no vacuum is applied to any of the three air door 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. ..." from F-150, F-250, F-350, F-Super Duty and Bronco, F-Super Duty Motorhome Chassis Workshop Manual

 

Check for a VACUUM LEAK; most likely under hood, white vac line to reciculating motor; it usually gets brittle due to location.. in Chris's Link, below see page 141

 

 

Electrical and Vacuum Troubleshooting Manual (EVTM) for an 86 (Partial); Speed Control on pages 135-139, A/C & Heater on pages 140-145, Radio on pages 127-129 Source: by Ford via Chris B (Blue, bronco boy) at telus.net

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yo,

I was in a rush..

on page 141 look @ bottom, Left, for the Legend

V=Vacuum

NV = No Vacuum

 

So, since all air flow is thru dash vents only; suspect that Vac is applied to da Panel door when it should be shut off... \

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& read on page 143 what is supposed to happen.. then figure out where the prob is.

GL!

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I have found the problem.It is the panel door. I think the hinges have broken. I want to thank you for your responces and the links. This site is extremely useful. I am willing to bet the two responses I've received are from the two most knowlegeable people on the site.

 

Thank you both, I would not have been able to solve the problem without your help. I really appreciate it.............

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Rustbucket86, I have the same truck with the same problem. I have also confirmed that the vac. motors are all working. What did you do to fix the problem? I would appreciate any DIY instructions you can provide. Thanks

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to date nothing............

I think the easiest way to fix it would be to go in through the heater core (behind the glove compartment)and on the left should be the panel door. Replace the panel door or block the register vents. If you have anymore questions feel free to ask.

 

If a hammer wont fix it it must be an electrical problem........

Edited by rust bucket 86

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