Air conditioning

[Guest]

I have a 1960 hardtop with factory air. With the entire system shut off on a warm day, I get warm air through the air conditioner vent. With the air conditioner on, I get cold air through the vent, but warm air from under the dash. The fresh air vents are closed on both sides and there are no holes or openings in the firewall.

Although its been 47 years, I do not remember any air coming in through the A/C vent with the system off in my parents 60 bird when it was new.

Can anyone tell me where and how to start looking for the problem?

[Alexander]

In what position are the knobs to the side of the temperature control? The left one controls the flap to the evaporator. In the "in position," the opening the evaporator is closed. The right one controls the flap to the cowl allowing outside air to get in. In the "in position," the opening the cowl is closed. Normally both of these should be closed. The left knob only should be pulled out when you use the heat. The right knob only should be pulled out when you use heat. With both knobs out, the outside air will come through the A/C vent above the radio, when the car is moving, regardless if the A/C is on.

Another reason you might get outside air through the A/C vent is if the cables to the flaps are not adjusted right or if the evaporator drains are rotted out. They are gone if you feel two 1 1/8 inch holes on the bottom of the fiberglass evaporator box. The fix for that is cheap, as Chevy valve cove breathers fit there as explained in another post.

[Guest]

In what position are the knobs to the side of the temperature control? The left one controls the flap to the evaporator. In the "in position," the opening the evaporator is closed. The right one controls the flap to the cowl allowing outside air to get in. In the "in position," the opening the cowl is closed. Normally both of these should be closed. The left knob only should be pulled out when you use the heat. The right knob only should be pulled out when you use heat. With both knobs out, the outside air will come through the A/C vent above the radio, when the car is moving, regardless if the A/C is on.

Another reason you might get outside air through the A/C vent is if the cables to the flaps are not adjusted right or if the evaporator drains are rotted out. They are gone if you feel two 1 1/8 inch holes on the bottom of the fiberglass evaporator box. The fix for that is cheap, as Chevy valve cove breathers fit there as explained in another post.

OK, I think the problem is the fiberglass evaporator box. I only found one drain hole. It is on the passenger side of the box directly behine the right valve cover. Where is the other hole? Also, what is the round pipe that extends about one inch out from the firewall to the left of the evaporator box and under the brake master cylinder. I am also going to have to seal the evaporator box on the left side where the freon lines enter the box.

Thanks for your help. How are you feeling these days?

[Guest]

I purchased the 3M flexible sealer from Eastwood. I sealed all of the holes in the fiberglass cover including the drain holes. Since I live in the desert, condensation is not an issue. The difference is amazing now that I am not air conditioning the whole world. I switched to a Sandan ?? compressor and this baby really blows cold, very much like new car.

[Meridious]

facing under the hood: There is one drain hole on the left, and one FAR under the right side, near the gear-shift linkage mount on the frame...

There is a thread here that lists two PERFECT replacement rubber filters that allow drainage, but does not allow air coming in. I cannot recall where I ordered these from, or what thread I found the details in, but they fit perfectly and worked very well.

It is possible that when you are closing off the hearer/turning on the AC, the flap is jammed partially open by failed, old rubber seal that is glued around the edges of the flap from the factory.

When I removed my AC, I saw that these old foam-rubberish strips designed to securely seal off the flap when closed...had deteriorated, fallen, folded, and was actually keeping the flap open about half an inch or so.

When I reworked my AC, I bought some 3m, long-lasting 3/4" by 5/16 self-adhesive foam stripping and replaced them. I added some super 3m glue as well.

On the passenger side, there is a kick-panel flap that allows air in from the outside. That might be jammed open as well.

My AC had never been removed before, and I was astonished at the deterioration of everything by the plastic/fiberglass.

Rubber was mush, the particle cardboard was fair, but any caulking or seals from the factory had become dust.

There are so many factors when dealing with these old AC units and evaporator housings!

[430bird60]

Relacement filter for a/c drains

Anyone know which thread MERIDIOUS was referring for replacement filters for the a/c drains on the evaporator box? Thanks.
Ken