Why is the air stream of my 1964 CC system weak-even though the blower is blowing strongly?

[Norman Silverman]

Hello All

I may have posted this before, but I was distracted by health issues and am now just getting back to trying to figure this out: The air stream (whether heat/def/AC) is weak, even thought I hear the blower churning really strong. Any clues?

Thanks

Norm

[Kurt]

Could be the mode doors. If they are not opening & closing as they should, the air will come out everywhere instead of just AC vents, or heater or defrost. Pull the glove box liner & run the the system with the engine running (needs vacuum to operate the mode door actuators) you should see the rod on top of the AC box moving as you cycle through AC, heat, defrost. While you're in there check that ducts are connected. If all that checks out, your blower could be clogged.

[Norman Silverman]

Thank you, Kurt. I've done that and the mode doors are working, just the volume of airflow is diminished at every setting. Heat comes out  below, defrost comes out properly, and AC  comes through the vents-just that the volume of flow is very little, even though I hear the blower running.

If my blower is clogged, I imagine the Evaporator is the most likely place. How to get to it?

[Dennis P. DiBari]

Norm,

How is the duct work under the dashboard going to all the vents?  Is everything connected and hooked up?  Just a thought.  Dennis DiBari

[Norman Silverman]

Thanks, Dennis. Yes, all good-I have had the dash top off to confirm. 

Norm

[Jason Edge]

Never really fully diving into the comfort control system (yet), here are some questions & thoughts:
- Have you tried Max Cooling vs Max Heating and noticed the same or different air rate. If say you get strong air below in Heat Mode but not so much in AC mode that might point to issues pushing air through the evaporator side.  The converse would point to issues pushing air through the Heater core side.

- Is your Power Servo, which controls the temperature door, working correctly. When in full AC mode it should have the door directing air through heater core closed drawing air only in the evaporator side. When in heat motor it retracts that door, closing off the the evaporator and only allowing air through the heater core. If it is only halfway pulling the door back it would probably produce less that full air flow. 

- Does the temperature door move back and forth freely. If you disconnect the power servo you should be to move back and forth.

- Make sure all ducts to AC vents are good ad Dennis  indicated. The right dash duct is really bad for breaking apart as it has to go through a very tight bend. You may be just dumping air behind dash if it shred and you are in "AC Mode". This is one reason I asked if you have checked in both max AC and max Heat mode.

- Finally, and hopefully this is not the case, I have see the rubber inserts/shields inside the box coming apart like the picture below that can restrict air flow. i would check everything else before pulling the air box. 

[Norman Silverman]

Jason

Thank you so much for this meaningful input-I think (unfortunately) you have "Cracked the Code"-the rubber shield in the airbox is most likely the culprit. The "restriction" I have identified behaves most like one that affects all modes of the HVAC operation-they are all diminished. Is there an access point where I might be able to snake my camera probe in to and take a look?

Norm

[Dennis P. DiBari]

Norm,

     If anyone would know, it's Jason.  Best of luck with the shield.  I have never tackled that.  I hope it works!  At least the duct work is good.

Dennis DiBari

[Norman Silverman]

One more thing, Jason: Where does that shield go? Is it a flap that moves back and forth, or is it a blocker of some kind. What I am asking is if I can reach it somehow would it be wise to just remove it? Or would removing it interfere with air flow operation?

Thanks

Norm

[Jason Edge]

Norm. that was the best/only photo showing blockage from inside. I am pretty sure it is not a moving flap as they would quickly weaken and come apart and more of a seal between metal parts/doors. I am guessing tacked to the metal with small staples or just glued. When I get back to my air boxes in storage I will try and take a better look. If you remove the power servo & transducer assembly from the air box it will leave a Big access hole into the box. There are only a few screws (5/16" hex head as I recall) holding it to air box. I cannot remember if you would have clearance with the air box still mounted in the car. With glove box insert removed it should. 

[Norman Silverman]

Much appreciated, Jason!