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Non AC dash control question

Discussion in '6.9L IH & 7.3L IDI Diesels' started by BrianX128, Jul 30, 2020.

  1. BrianX128

    BrianX128 Supporting Member Supporting Member

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    So in my 1990 F150 that was non ac, I added ac a while back. One of the curious parts I chose not to mess with was the dash controls because the donor truck had the ugliest destroyed hvac panels ever, so I put a toggle switch to send power to the low pressure switch on the drier to give power to the ac the same way normal ac and max ac do. I just put the slider to vent and press the button and ac is on. Works great.

    After my debacle with some of my ac components on my 350 I started thinking about the recirculation door and what is it doing on this truck and it turns out when the truck is off the recirculation door is "recirculating" but on legit any setting while running it opens to "vent" outdoor air.

    I'm guessing my only option is to sit the little vacuum doohickey backwards so it does nothing and manually leave the door on recirculation mode for summer when you'd never want outside air or rig up some sort of choke cable to the door? It's not like my settings do anything but that seems wrong as my non ac hvac blower housing had a recirculation door / vacuum module in the same spot.. I can't figure out why if it does nothing?
     
  2. chillman88

    chillman88 Supporting Member Supporting Member

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    Not completely sure what your question is...

    "Off" closes it to recirculate so you don't get air blowing in all the time going down the road. Not a huge difference, but definitely noticable.

    The only difference between AC and MAX AC as far as I know is AC is outside air and MAX AC is recirculated air.
     
  3. BrianX128

    BrianX128 Supporting Member Supporting Member

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    I'm just trying to think how I can use this since my truck has ac now with the wrong controls. Maybe if I turn it backwards so if I have the air on in any capacity even heat its recirculating but when its truley off it would be a vent? Disconnect it entirely and use a throttle cable? Haha
     
  4. chillman88

    chillman88 Supporting Member Supporting Member

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    Ah ok.

    The only time it's closed is when vacuum is applied. Might be able to rig up a 12v electric vacuum pump directly to it from a superduty. That way you could just flip the switch to close it, use some kind of 12v solenoid to vent it to let it open again.
     
  5. dgr

    dgr Full Access Member

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    This and an on/off push button. Or a zip tie and a plug for the vacuum line.... solenoid-valve-vac-2-port-wbrkt-29-40000-air-conditioning-don-brown-bus-parts_786_940x.jpg
     
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  6. chillman88

    chillman88 Supporting Member Supporting Member

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    Do you have a part number for that?
     
  7. dgr

    dgr Full Access Member

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  8. BrianX128

    BrianX128 Supporting Member Supporting Member

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    Interesting. Found a similar one on Amazon prime for 18$ might have to order one and wire that into the same wire as the low pressure switch so if the compressor is on I'm recirculating. Curious why there is two hoses and if one is an inlet and outlet for the vacuum.
     
  9. chillman88

    chillman88 Supporting Member Supporting Member

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    Two hoses where on that solenoid? That works just like a valve, either open when it has 12v and closed normally or vise versa. To use it the way you want would require you hook it directly to the vacuum pump and plug the old recirc control hose into a check valve somehow so they're not fighting each other, that way the recirc door would still close in the "off" position.
     
  10. BrianX128

    BrianX128 Supporting Member Supporting Member

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    Ok so I plug my existing hose to the recirculation door, and splice right into vacuum that is always on when the engine is on and use the valve off a switch. Gotcha.
     
  11. aggiediesel01

    aggiediesel01 Full Access Member

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    @BrianX128

    I've got a good a/c panel out of a '91 I have no use for. You pay the ride and it's yours. Probably needs a fan switch as the back side is discolored from heat but I think it's good otherwise no broken mounting tabs or brackets. The Temp Blend cable isn't attached but it's the same for all.
     

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