What does this do? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ddsmith · 07-20-2003, 09:47 PM

So what is the purpose of the damper in the cowl area and is it open or shut with vacuum applied. It's the one attached to the other end of the diaphragm in the top corner of this picture.

Longhorn Man · 07-20-2003, 09:54 PM

A/C component. Can't tell you what it actually does though.

*racedvl* · 07-20-2003, 09:59 PM

It is for max a/c. That will close so no outside air enters the cab, the same reason the kick panel floor vent is vacuum controled.

ddsmith · 07-20-2003, 10:10 PM

Thanks racedvl,
So the way I understand it is that the cowl vent draws some replacement air into the cab but in max air position it closes. The big question is where does the air actually enter at.

casey · 07-20-2003, 10:17 PM

well on my wifes bronco that gismo that is vacuum controled shuts the hot water off from even entering the heater core, if I see it right

jef5150 · 07-20-2003, 10:18 PM

help???????

Class of 69 · 07-20-2003, 10:23 PM

On the original heater box, it was pulled in from under the cowl, thru the hole in the fire wall by the fan. You have eliminated that hole with the plate on there now. Does that install have a fan that pulls air from outside at all??!!

ddsmith · 07-20-2003, 10:52 PM

Class of 69,
That is correct it doesn't pull in outside air but I think I have a possible resolution. The kick panel vent that is vacuum controlled could be left operational and you could select the amount of outside air via the upper control on an A/C control panel. The A/C people want their units to cool really good. They attempt to stop all outside air from entering the cab. I understand why they look at it in that way. They don't want you to complain because the unit isn't keeping you cool enough. If your drawing in 95-100 outside air you pose a very large load on the system. Your house doesn't draw in outside air with your A/C system does it? Well it may if you've got one of those real expensive setups. Most of us rely on leakage and the opening and shutting of doors to exchange the air.

07-20-2003, 09:47 PM	#1
ddsmith Glowing since 1978 Join Date: Mar 2001 Location: Lusby,MD,USA Posts: 532	What does this do? So what is the purpose of the damper in the cowl area and is it open or shut with vacuum applied. It's the one attached to the other end of the diaphragm in the top corner of this picture. __________________ 66 Chevy C30 Stakebody Dump, PS,PB, 327cu in 71 Corvette Coupe 454 4 speed 69 Chevy C20 Custom Camper

07-20-2003, 10:10 PM	#4
ddsmith Glowing since 1978 Join Date: Mar 2001 Location: Lusby,MD,USA Posts: 532	Thanks racedvl, So the way I understand it is that the cowl vent draws some replacement air into the cab but in max air position it closes. The big question is where does the air actually enter at. __________________ 66 Chevy C30 Stakebody Dump, PS,PB, 327cu in 71 Corvette Coupe 454 4 speed 69 Chevy C20 Custom Camper

07-20-2003, 10:18 PM	#6
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	diagrahm help??????? Attached Images

07-20-2003, 10:23 PM	#7
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	On the original heater box, it was pulled in from under the cowl, thru the hole in the fire wall by the fan. You have eliminated that hole with the plate on there now. Does that install have a fan that pulls air from outside at all??!! __________________ 69 GMC K10 ..some restoration required....still..

07-20-2003, 10:52 PM	#8
ddsmith Glowing since 1978 Join Date: Mar 2001 Location: Lusby,MD,USA Posts: 532	Class of 69, That is correct it doesn't pull in outside air but I think I have a possible resolution. The kick panel vent that is vacuum controlled could be left operational and you could select the amount of outside air via the upper control on an A/C control panel. The A/C people want their units to cool really good. They attempt to stop all outside air from entering the cab. I understand why they look at it in that way. They don't want you to complain because the unit isn't keeping you cool enough. If your drawing in 95-100 outside air you pose a very large load on the system. Your house doesn't draw in outside air with your A/C system does it? Well it may if you've got one of those real expensive setups. Most of us rely on leakage and the opening and shutting of doors to exchange the air. __________________ 66 Chevy C30 Stakebody Dump, PS,PB, 327cu in 71 Corvette Coupe 454 4 speed 69 Chevy C20 Custom Camper

07-20-2003, 09:54 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	A/C component. Can't tell you what it actually does though.

07-20-2003, 09:59 PM	#3
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	It is for max a/c. That will close so no outside air enters the cab, the same reason the kick panel floor vent is vacuum controled.

07-20-2003, 10:17 PM	#5
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	well on my wifes bronco that gismo that is vacuum controled shuts the hot water off from even entering the heater core, if I see it right

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