A/C air leak inside???????

[Peter B.]

I am re-vamping my interior and noticed that I am not getting lots of air-flow. When I put my hand back toward the firewall, I noticed that where the AC duct housing mounts to the firewall, I feel air leaking out.

Is there some type of insulation strip used that could have worn out? Any recommendations on sealing this?

Thanks

[Don H.]

Re: A/C air leak inside???????

What year? Roadster or coupe? Don H.

[Jack H.]

Re: A/C air leak inside???????

Yes, there were a number of seals on the original cockpit duct work of your '71 A/C car. The Dr. Rebuild catalog gives nice pictorials of what seals were used where, BUT it's a reasonably major job to pull the Harrison box apart to replace all of the seals with fresh/new. Plus, there are several issues that can lead you to 'think' your air box is leaking when it's not....

First, the early Shark cars (your '71 falls into this category) were equipped with 'lap cooler' vents on the bottom of the driver/passenger ducts serving the RH/LH vents. Operation is covered in your copy of the owner's manual.

Essentially, you 'spin' these vent louvers to open/close. When opened, they allowed cold air to spill straight down onto your feet. Each of the A/C vents has an open/close 'switch' allowing you to shut the system when you're not calling for A/C. If the car is a convertible (or coupe with T-tops removed), the overhead flow of outside air will create a cockpit low pressure center and you'll 'tax' the A/C system's sealing integrity if you don't shut down each of the vents.

Second, the A/C system runs in one of two modes: (a) takes outside air for makeup, or (b) takes its makeup air from the cockpit (recirculate) depending on how the A/C control switch is set. There are two vac controlled vent doors in the RH fender/plenum that work on a 'flip flop' basis to switch the source of make-up air. These vent doors weren't known for SOLID sealing when new and tend to 'tucker' out as they age.

So, it's possible to have makeup air vent doors that don't fully seal and you get outside air flowing through the inside makeup air vent door (when it shouldn't) and entering the cockpit through the passenger side kick panel louver. This is ESPECIALLY true if you drive with windows open, top down, or T-Tops off and have the extra burden of an exterior air 'ram' effect.

If you're driving and reach over to feel for the source of the air leak, you can confuse air coming into the cockpit through the makeup air plenum for air leaking around the Harrison distribution box. To be sure, have someone else drive the car, sit in the passenger's seat and investigate thoroughly....

[Jim T.]

Re: A/C air leak inside???????

Peter is this test of your air-conditioner while revamping the interior done with the only the blower on?
With the car running and air on MAX and the temp wheel rolled back on the right your right kick panel vacuum motor should open the MAX air only door to pull in air from the interior to recool it.
The cowl ambient air entry located at the top of the right rear fender and difficult to see with the wiper door down should be closed to keep out the warmer ambient air. This plastic door is controlled by a vacuum motor and the hinge of this door is also plastic and part of the whole plastic door, so it could of broken. It is replaceable. If you move your air conditioner select to the air conditioning switch position just below MAX this door will open to allow ambient outside air to be cooled and the kick panel metal door will close.
The metal door in the kick panel has a seal around it that is most likely deteriorated and not sealing anyway, but the door should open and close.
One other vacuum motor that operates a door is in the heater/air conditioning ducting located just above the passengers left footwell area.
The ductwork going to the drivers left vent could be missing which would not give you any air flow from this vent, or it could be proberly intstalled and leaking air at the connections.
Another possibliity is that the air conditioner coil in the housing in the engine compartment could have some blockage.