Tiger69

I have the inside and outside HVAC box out of car and all gaskets are bad or missing. I saw a thread on making the facing gaskets. But the flap gaskets are gone for the most part. My Olds body/chassis manuals dont go into that much detail. Would a parts manual show pictures? Anyone fabricated those gaskets? Any input is appreciated. Thanks.

cfair

I made some seals from adhesive backed closed cell foam tape. You can get it at a decent hardware store in many thicknesses and widths. I’d match the factory thickness and worry less about the width as long as it seals. Slice and score it for shape and corners with a fresh xacto knife and you can make good precise clean looking seals and gaskets with a bit of practice.

Lengthwise sliced vacuum lines work well for this job too. Vacuum lines cling to edges very well if cut right and notched for corners to sit flat.

The only thing I’d do special is glue the foam in place with 3M strong trim adhesive since you won’t want to go back in anytime soon. Maybe even drive a short 1/4” head head screw or 4 to mechanically retain the seal.

I also use 3m Dum dum sticky strips in fairly large quantities for this kind of job. Like for the plastic HVAC housing to the firewall seal. This is also a good time to clean and vacuum all the heat exchangers, replace the blower resistor, and maybe swap in a new blower fan.

Look around under my user name and you should find a note about this job or similar. Just did my ‘66 Starfire in the last 6 months with this system.

cheers
cf

Tiger69

Tiger69

Thanks for the response. I understand improvising, and like the idea of splitting hose for edge flap seals. The internal gaskets are gone, so have nothing to duplicate. But, your reply was encouraging. All 3 vacuum actuators bad as well and need to search for replacement. Saw some on a classic AC website.

cfair

They mode door gasket was about a 1/4” thick and about 3/8” wide. This size closed cell foam tape is readily available for sealing home doors and windows. If I recall there’s even an indent or lip in the mode door which informs you on the width of the gasket. 1/4 thickness or height is about all you need to keep it sealing and from rattling around I there. I even put some closed cell foam around the edge of the heater core to force air through, not around it.

I’d avoid doing this on the evaporator though since it needs to “breathe” and allow condensation to run out. For good smelling A/c clean that evaporator we’ll while you can get at it. I vacuumed and brushed mine a few months back. Also consider shooting that a/c mold killer in there while it’s open just to be sure.

Tiger69

I have searched the forums for threads on AC HVAC, even on A-bodies, for many hours. I took the AC dash out of a donor '65 Olds 98 4 door hardtop to put into a non-AC 4 door hardtop. I took the HVAC box apart to replace heater core, evaporator, actuators, and gaskets. There are four doors in this big body HVAC box. The temp door is cable operated and is not spring loaded. The Recir door and mode door are vacuum operated and are spring loaded. The defroster door is vacuum operated but there was no spring or gasket on the door. Is it a safe guess that vacuum operated HVAC doors are going to be spring loaded, and the one I have is missing a spring? I have studied the pictures in the CSM but I can't tell by the diagrams. Once I figure the spring part, I will experiment on what the defroster door had for gaskets. Thanks.

Prior to taking HVAC box apart