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I have an 81 bronco. Im wanting to know what all a/c related parts i can remove from the firewall and still have a working defroster. I havent had a working a/c in 15 years. I removed the compressor 10 years ago and bypassed the heater core when it began to leak. I have no intentions of ever fixing the a/c. I dont even need a heater just a defroster for keeping my windshield free of fog.
 

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The A/C does just as much for removing fog as the heater which is why all vehicles use both the heater core & the A/C system when DEFROST is selected. The fog is water inside the cab; the A/C dehumidifies the air, so there's less water to create the fog. The heater takes much longer to work because the engine has to warm up first; the A/C begins working instantly. Heating the air does 2 things: 1) it decreases the air's relative humidity by increasing the amount of water it CAN carry which also moves the air away from its dew point, and 2) it warms the glass so the humidity (which is coming off YOUR skin & from YOUR breath) doesn't condense there as readily.

Without A/C or heater, you're left with nothing but a blower. And blowing cold air (which is usually at 100%RH) across the windshield won't remove much condensation. Carry a roll of paper towels.
 

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That was my next plan! Thanks for the reply. I was also considering uying one of those mojave heaters. Are you familiar with them? If so what factory parts would i need to retain in order for it to work? I really need those parts gone off the firewall to keep my tire from rubbing on them at full flex. Pls im wanting to relocate my solenoid and other wires back there since ive trimmed so much of my fender.
 

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The A/C does just as much for removing fog as the heater which is why all vehicles use both the heater core & the A/C system when DEFROST is selected. The fog is water inside the cab; the A/C dehumidifies the air, so there's less water to create the fog. The heater takes much longer to work because the engine has to warm up first; the A/C begins working instantly. Heating the air does 2 things: 1) it decreases the air's relative humidity by increasing the amount of water it CAN carry which also moves the air away from its dew point, and 2) it warms the glass so the humidity (which is coming off YOUR skin & from YOUR breath) doesn't condense there as readily.

Without A/C or heater, you're left with nothing but a blower. And blowing cold air (which is usually at 100%RH) across the windshield won't remove much condensation. Carry a roll of paper towels.
Is that just a long way of saying "fix the heater core, it'll take 40 minutes and 40 dollars, won't defrost as well as if you had A/C but will be tons better than trying to defrost with no heat"?
 

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Is that just a long way of saying "fix the heater core, it'll take 40 minutes and 40 dollars, won't defrost as well as if you had A/C but will be tons better than trying to defrost with no heat"?
Lots of Bronco don't have AC. But all bronco's had defrost. You need heater core at a minimum. The only things you could remove is the vents and the hoses to the vents. but remember to cap them off.


Good luck!
 

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Discussion Starter #6
So i can remove the blower and box thats mounted on the firewall and patch the hole. Just leave the heater core?
 

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So i can remove the blower and box thats mounted on the firewall and patch the hole. Just leave the heater core?
If you remove the blower how is the warm air gunna get to your winshield?
 

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So i can remove the blower and box thats mounted on the firewall and patch the hole. Just leave the heater core?
The heater core is in the box that is mounted to the firewall and the blower is what provides the air to force the heat through the heater core for the defroster.
 

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without the bloewer whats going to make the warm air go across the windshield? you can get a blower box from a truck that didn't have A/C and it will be smaller and easy.

what steve was saying is to have both A/C and heater working to really get the best defog.

are you trying to free up some room? whats the reason your trying to stip everything down?

in my old 96 I used an airbox form a Explorer because my wheeltravel destroyed the original and I wanted a smaller one to help clear it. had to fabricate a sheet of metal to go on the firewall but that was easy. if I wanted to I could have made all the A/C work correctly. it did free up alot of room and wasn't very hard
 

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These trucks have the easiest heater core of all time. Seriously it will take you longer burp the air out of the system than it will to change the damn core.

Quit being such a cheapass. Without a blower and hear your windshield will never be clear.
 

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without the bloewer whats going to make the warm air go across the windshield? you can get a blower box from a truck that didn't have A/C and it will be smaller and easy.

Here is an image of the interior box in my 79 and my Bronco did not have Factory AC, I just removed this box to install my new custom AC and Heat.




On the AC version there is a big box on the exterior of the firewall on the passenger side.



On the passenger side this is a heater only Model and all you can see on the firewall in the engine compartment is the blower motor sticking through.

 

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My 84 has the blower/ac box in engine bay, heater core inside. I removed all my ac shit except the box... I was researching awhile back and someone told me if i remove the plastic ac box in engine bay things wont work right something about blend door etc. BUT i had seen some guys online who have removed it and put a metal cover over and claim to still have defrost. I am going to tear it apart in the next few weeks myself because sometimes ya just gotta try haha. Ill post up here with my findings.
 

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Thanks for all of the responses except (theunforgiven) its not that im trying to be cheap. I use mine rockcrawling and need more clearance when my tire is completely tucked. I have already removed my inner fender wells aswell as trimmed 4" of fender. I dont need or want a heater i was just concerned with defrosting the windshield. I asked previously if anyone had any experience with a Mojave Heater and if so would i only need to keep my heater core? On the 81 the heater core is on the inside of cab and the HUGE blower is outside with another box directly beside it.
 

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Thanks for all of the responses except (theunforgiven) its not that im trying to be cheap. I use mine rockcrawling and need more clearance when my tire is completely tucked. I have already removed my inner fender wells aswell as trimmed 4" of fender. I dont need or want a heater i was just concerned with defrosting the windshield. I asked previously if anyone had any experience with a Mojave Heater and if so would i only need to keep my heater core? On the 81 the heater core is on the inside of cab and the HUGE blower is outside with another box directly beside it.
I would bet you could make a 78/79 heater only interior box work for what you need. It only requires a few things. 2 holes in the firewall for the hoses, 1 hole the motor sticks through about 2 inches. If you just use recirculated cabin air you don't even need to hook it to the passenger vent box. Wire it up and you have a working unit.
 

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If you just use recirculated cabin air...
It would never defog. By the fact that the glass is being cooled by the outside air, and that temperature is too cold for the amount of water in the INside air, you can know with certainty that the outside air carries LESS moisture than the inside air. So it makes no sense to recirculate the inside air, with all its moisture, at any temperature. Raising the inside air's temperature will only make it pick up MORE water, causing MORE fog on the glass.

Heating the (relatively) dry OUTside air will make it pick up inside water, carrying it out as more outside air comes in.
 
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