i found something interesting while removing my ductwork...
as you can see in the pic, there is a big gap between the defroster duct and the main box below it...
this cant be right...wouldnt that mean that a lot of my a/c is escaping there???
below my dash???
shouldnt i seal that up?
also...does the a/c come thru the heater core? if so would i get better a/c "volume" without it in there?



[Modified by SIGNGUY, 10:16 PM 10/9/2003]

 

I just went through this. Mine ended up ligning up closer together after I took everything else apart and replacing all the weatherstripping/seals in the duct work. Then I took some cloth style duct tape and wrapped all the joints like that one. You will appreciate all of your effort after you hand fit all the parts together correctly. What a difference it makes! If you still have a gap, I don't see a problem in using a good quality duct tape from the hardware store to seal it up as long as it does the job.

 

hey SIGNGUY, Im glad you are doing your interior now.. My car is in the EXact same stage as yours. and frankley im loosing movation, the "while im at its" is beating up my wallet.
Im looking at your work , and saying to my self, IF he can do it than I can do it .
for some twisted reason by looking at your progress im getting movotated to complete this stage of my car.
thanks

cheerts
chad


[Modified by 71'AirStrike, 12:53 AM 10/10/2003]

 

Don't feel bad Chad, mine looks EXACTLY like that right now.

In fact, my butt needs to get back out there.

 

I had the same gap on my 74, and that's exactly what I did. Maybe that kind of tape used for heaters/furnaces would be better, but so far it seems that the duct tape is holding up allright...

:cheers:
-Pedro

 

I agree with the other guys, replace all the seals and wrap all the joints with aluminum tape. Not Duct Tape, duct tape will eventually dry out and the adhesive will harden. The aluminum tape is available from Home Depot, Lowe's and many other home repair stores.
Seal all the boxes and tape all the joints and you'll be surprised at how much air comes out of the vents, when the A/C is on.
Actually I don't think that the air is routed through the heater core at all times. All the air from the fan does go through the evaporator, after that it depends on whether you have the controls in the heat position of air position. If in the heat or defrost position a diverter closes a flap and the air is pushed through the heater core and then out the floor vents. If defrost is selected the same diverter routes air from the fan through the core, but closes the floor vents and opens the actuator going to the defroster vent.
The seals on the diverters aren't perfect and that's why heat will leak into the air from the heater core. A correctly working vacuum operated water cutoff valve is supposed to keep hot water out of the core unless the heater is on, these valves often corrode and quit operating. Manual cutoff valves are a quick fix, that truly isolates the core from the hot water from the water pump.
If everything, all the actuators, all the vacuum lines all the ducts are working to spec's, then the heater and A/C will work as good as a modern vehicle. The mistake that a lot of people make(me included) is we try to fix a problem with one fix, where maybe the whole system is in need of repair. In my case I put in a bigger C-4 fan, I got more air, but not much. It wasn't until I pulled the dash and looked at the whole system that I saw that it was more than just the fan at fault.

 

just finished my a/c project... i agree that some well placed duct tape at the last minute could really help out those minor escape paths... my ducting ended up being made of some drier vent material from the nearby hardware store... lol... the ac (at least on my '80) is diverted away from the heater core in a/c mode by a vacuum controlled panel (not sure of the technical name for this part), so the heater core shouldn't make a difference, unless the systems vacuum control is having problems or changed for some reason...

 

thanx everybody... :)
anybody else got advise???
:lurk:

 

Signguy, I just redid my HVAC system. Mine had a similar gap. I used duct tape to wrap around it and make a seal. This is the defroster duct and doesn't get used much here in FL. I also bought a seal kit and replaced all the foam seals throughout. There is some room for adjustment but you still end up with a gap or poor seal. Try to clean all the dust off before sealing so the tape will stick really good. I replaced the A/C evaporator, the evaporator housing, heater core, and all the seals. The A/C works excellent now. :chevy

 

i have decided that i will wrap the gap with Reflectex and secure with some large zip ties that i have...
i think that will outlast any tape...