Outside air intake?

[Napoleon_Tanerite]

Where does the air come in from with the heater system turned off? Is there a way to block it off while retaining heater functionality?

 

[kassim503]

I dont think the CUCV's had a fresh air feature built into the box, its always recycled by getting sucked in under the pass. side dashboard.

 

[Barrman]

The air comes in all the time from the cowling between the hood and glass. I assume this question came up because your add on a/c is blowing cold and you have a flow of fresh hot air coming out either the floor or the defrost vents? Besides finding a civi resurculation door, housing and installing it. I really don't see a solution besides setting the heater to defrost and stuffing rags in there.

 

[OL AG '89]

I think you could possibly put a T-fitting on the heater coolant lines under the hood. You could then just redirect the hot water without passing through the heater core in the cab.
you wouldn't get any heat from the heater core until you removed the "bypass"

 

[Barrman]

I don't think his issue is the heater core putting out heat. Moving the stock slide to the far left takes care of that. It is the ambient air coming in that is killing his add on a/c effectiveness if I understand him correctly.

 

[Napoleon_Tanerite]

I don't think his issue is the heater core putting out heat. Moving the stock slide to the far left takes care of that. It is the ambient air coming in that is killing his add on a/c effectiveness if I understand him correctly.

that's correct

 

[carter262]

Did anyone ever find a solution to this?

My M1009 is blowing hot air through the floor vent, stronger flow the faster your drive, event with all the heat controls turned to the off position. It's 90 some degrees outside and the heat is killing me.

 

[Barrman]

When I did the add on a/c to my M1009. I found duct tape on the floor vents with the top slide set to floor works real well. Unless you drive over 70 for a long period of time and the duct tape pops off from the air flow. I carry a roll under the drivers seat and reapply as needed.

There really isn't a technical fix to this since the stock heater system is designed to let in fresh air. Vintage Air complete HVAC in dash unit blocks of the fresh air and gives you vents to feel heat or cold in your face. But, that is a $1,500 fix.

 

[carter262]

Thanks. I was worried that was the case.

 

[cucvrus]

Did anyone ever find a solution to this?

My M1009 is blowing hot air through the floor vent, stronger flow the faster your drive, event with all the heat controls turned to the off position. It's 90 some degrees outside and the heat is killing me.

The foam sealers/gaskets on the flapper door are gone. I would suggest getting the heater box out and replacing the seals/foam/gasket with something that will seal the heater core. Another way is to put a water valve in the heater hose feeding the heater. Seal off the hot water that is going to the heater. Quick fix and no need to drain the cooling system. Cost less then $10. for a valve with barbed connections. Good Luck.

 

[carter262]

Does the fresh air that comes in from the cowl at the windshield go through the heater core?

I was thinking of taking off the cowl and sealing / covering the fresh air holes. Has anyone done this? What are the down sides?

 

[cucvrus]

That will rust your rockers and front cab panels. That is part of the was and dry rocker panel design. But do as you wish.

 

[german m1008]

Did anyone ever find a solution to this?

My M1009 is blowing hot air through the floor vent, stronger flow the faster your drive, event with all the heat controls turned to the off position. It's 90 some degrees outside and the heat is killing me.

I think it looks like this........like cucvrus said

after some work it could look like this........

 

[carter262]

Did that stop the bleeding trough air when the vents were in the closed off position?

 

[cucvrus]

Also the air vents on the kick panel will be disabled and it will still catch air from the bottom of the cab cowl. I would say replacing the heater box flapper door seals is the best bet. Have a Great Day. ​

 

[carter262]

I think it looks like this........like cucvrus said
View attachment 733481View attachment 733482View attachment 733483
after some work it could look like this........
View attachment 733484View attachment 733485View attachment 733486

Okay took the one off my parts truck. So the flap in the second picture is supposed to have foam on it to seal off the air flow when closed, correct?

Mine doesn't have any foam in it anywhere but all flaps seems to working correctly when you move the levers.

 

[carter262]

Okay, I have really look this over now. It appears to be designed to allow air flow from the outside even when all levers are in the off position. It appears that the air will flow around the heater core when the heat is off and when you cut the heat on the flap closes that fresh air bypass and directs air through the heater core.

So this is a problem for me. I have installed a Nastalgic air kit so I have AC. The hot air coming in from the floor event when the heat is off is not helping at all. Especially when its in the 90's outside.

So I am going to block the fresh air bypass and put foam on the flaps to help them seal. I think I can cut a piece of sheet metal or plastic fit it down in the hole and seal it with silicon. That should do the trick. I will not have fresh air through the dash vents but I don't care. I only run it when I need heat anyway.
The red outline on the picture is where the fresh air goes around the heater core when heat is cut off.

 

[Gunfreak25]

Did blocking off the red outline circled above in the factory heater box yield blocked fresh air? Holy thread resurrection batman

 

[carter262]

Did blocking off the red outline circled above in the factory heater box yield blocked fresh air? Holy thread resurrection batman

I did end up blocking off the bypass. I had good and not what I wanted effects.

The good was during the winter the heat seemed to do better. All the air was directed through the heater core which helps.

During the summer with the heat cut off (the flap is closed against the heater core) there still is some hot air coming through the floor / under the dash vent.

I feel that it helped. If I had to do it over again I would probally do it because I feel that it helped the heat during the winter months.

 

[als804]

This is what i want to find. I have also custom A/C . In summer i notice there are hot air under the dash This unknown hot air always comes through heater unit in to inner even when all levers are off positions. I thought outside hot air flows from cowl vent through heater core in. I have to block red circle!