Fresh Air Vents

Courtesy of Eugene Fisher

Years ago we told a joke. "My car has 4-40 air conditioning. Four windows down at forty miles per hour." I guess you could call this 2-60 air conditioning. Two vents open at 60 miles per hour.

The GMC needs more fresh-air ventilation while driving. Owners told me they did not like the wind wings because bugs and rain would come in and required screens to be added. None of the arrangements seemed satisfactory. Money and effort are required to add extra air-conditioning under the passenger seat to provide added capacity. The addition owners universally enjoyed are adjustable fresh air vents from the coach grill to the driver and passengers' area.

This is not a replacement for air-conditioning, but if the outside air is clean and cool it will do a better job and take a load off of the motor.
I used three inch blast gates designed for sawdust removal in wood-working shops. I used the aluminum versions because they are stronger and are held together with screws that could be used to attach mounting brackets.

Cable mounting brackets were attached to the gates to hold the sheath and wire of the push-pull controls. The controls should have more than a three-inch operating range. Mine were too short and would not open the gates completely. I will change to longer controls when I find them.

The resulting assembly is self-contained and does not require any additional mounting holes or brackets. Three inch holes are drilled in the floor boards and two mounting bolts hold the blast gate to the floor. Two of the four bolts around the blast gate center circle were used to mount the assemblies to the floor. Space is limited for the driver side three-inch hole in the floor board. The easy mounting is between the accelerator and brake pedal as shown in the picture.

The drivers' push-pull control was mounted just below the emergency brake control. This location was chosen because the mounting was easy, the driver could reach the control, and no holes were required in the dash. The control is not heavily used and so it was mounted out of the way.

The passenger side vent was mounted as close to the side of the coach and as high as possible. I did not want to make a hole in that excellent, flat floor board that the passenger uses all of the time. The push-pull control was on the floor below the vent hole for the same reasons given for the driver side controls.

The input hoses to the blast gates were also sawdust removal equipment. The locations chosen for the blast gates allowed the hoses to be easily routed to the front of the grill. The current hose mounting is in the grill. They are squashed slightly and pushed out through the center slot of the grill.

In the future, when a rock screen is placed behind the grill, the vent hoses will be hooked to the rear of the screen so they will be hidden. The mounting for the hoses to the screen will be using an ABS blast gate that has been split into two parts. The two parts are cheaper than any other connector and have a flat surface for mounting to the screen.


Trendlines (Phone 800-767-999)
QuantityDescriptionCat. No.Price
2 ea.3 inch Blast GateDF121$16.00
10 feet3 inch Hose - BlackDF100$13.50
1 ea.3 inch ABS Blast GateDF105$  4.46
4 ea.3 inch Hose ClampDF117$  2.80

Hardware Store
2 ea.Push-Pull Control$14.00
2 ea.Wire Bolt(control wire)$  2.00
10 ea.10-24 x 1 inch Stainless Bolts/Nuts$  3.00
Misc.1/16 inch Al. Plate

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© 1998 by Patrick Flowers. All Rights Reserved
Revised 8/3/98