Folks, I have a 1969 and am trying to find some guidance/direction on how to go about cleaning out debri from the ductwork on the AC/heater system in order to help increase the airflow (right now when I turn the AC on hi, very little (it is very cold) air comes out the vents. I was told that debri might have collected over the years and might be the reason for the low airflow.

Anyone have any step by step actions on this for a 1969?

Also, any other recomendations on getting more airflow IF this doesn't work? I am new to the classic corvette world, but not new to working on an older car.

Thanks in advance everyone!

Ryan

 

Something you might want to try. The lever that is used to close off the center AC vents is connected to a vane that blocks air flow to the vents. I noticed that if I held the lever back, I would get more air. In it's relaxed open state it was blocking a lot of air. I figured i would take it off and fix the problem. When I took it off, I realized there was no 'problem', it was just not going to stay open enough to let the maximum amount of air through. So i decided to take it off. What a world of difference!

That vain really isn't needed. You can still block the air by closing the diverters.

So, check and see if you get more air out if you hold the lever back with the air on max. And if so, try taking that vain off. Before I could barely feel the air with my hand six inches away from the outlets, now I can feel it on my face when I'm leaning back in my seat!

 

I took my evaporator out and it was half full of leaves even with the leaf guard installed. Had to vacuum it out. Not easy to get to, but I had my engine out at the time.

 

Any instructions or guidance on how to do this?

 

I'm in Austin...will give it a try....how would I remove it?

 

My AC plenum was also 1/2 full of leaves. I completely disassembled my AC so it was then easy to get rid of the leaves. My engine is out.

With the engine in, I think you can get rid of most of the debris by removing the AC fan motor and just sticking you hand in and pulling out all the leaves. Their may still some debris in the evaporator core. Maybe you could work a high pressure air nozzle in their and blow this debris away. Don't know if this is practical.

For working on you car, an air compressor and air tools are not that expensive and are really useful.

 

I completely went through my A/C last summer installing a new seal kit. Getting the fan casing and evaporator casing out from the firewall side in one piece was not real easy it’s the hardest part of the job. My compressor was not hook up so I did not have to deal with that part. I ended up removing the passenger side header and even the valve cover to get the unit out. Upon disassembly of the casings a large ball of pine needles fell out of the evaporator side. All rolled up decomposing in there. When I began reconditioning the unit I noticed that the evaporator side of the casings lower corner was a little thin sort of dried up. Heat from the exhaust manifold had sort of deteriorated the fiberglass. After cleaning and glassing and over all reconditioning the unit I reinstalled it in two piece as I did not want to scratch it up. The fan side in first and then the evaporator side next. The two sides just screw together and then to the firewall as one unit You have to remove the side grills and work some through there. It’s not an extremely difficult job it just takes some time.

 

Been there, done that and took a picture.

It's hard to tell from the picture but all this junk only left about a 2" x 3" opening for air to pass through.

Unfortunately this isn't an easy job. As 68/70Vette said you can remove the blower motor, reach your hand in there and get most of it out.
But you will still have debris embedded in the core.
The only way to do this right is to remove the evaporator box from the engine side, disassemble it and blow compressed air through the evaporator core fins.
Since it sounds like you A/C system is still charged you will have to take it to a qualified mechanic who can evacuate your refrigerant, store it, and recharge it after your repair is made.

Another important factor in having good air flow to the cabin area is to make sure (and I mean really sure) you have a good seal between the evaporator box and the firewall.
Place a straight edge across the firewall and make sure it's flat.
Or at least flat enough that what ever you use to seal between the box and firewall will take up any voids.
For me, once I got in there I found that the debris was the least of my problems. I found a huge section of the blower motor housing missing.

I don't think air flow through the heater ducts in the C3 was all that good to begin with because if you do a search on this forum there are some people that have done a C4 blower motor modification to increase the air flow through the ducts which is suppose to work pretty good.
Once again, take your time making sure you have a good seal that's the most important in my opinion.
After I repaired mine it won't blow the hat of your head but it's good.

 

It's very simple. There are 3 screws that hold the air vents, and wiper switch to the bezel. Two of the screw go back and screw into the AC duct, and the third screw up, and into the bezel.

When you remove these screws, you will need to disconnect the connector to the wiper switch - take note of the wires on the connector, it's not 'idiot proofed', and will go on backwards. It's annoying to get it back together and have the wipers come on as soon as you turn on the car.

After you remove the vents, you will see what I'm talking about with the lever/vane. There is one screw on the side that holds it on. Remove that screw, and you can then wiggle the lever/vane piece out.

I was planning on upgrading the blower motor, but after this, I'm thinking I probably won't need to. The true test will be this upcoming Austin summer.