I've searched the site and see that the fan always runs when ignition is on but my question is in relation to air volume. Where would that be discharging air from? Defroster, a/c vents? Also the volume of air from any exit point seems minimal at best regardless of fan speed. It also seems as there is no high speed. The blower motor seems a bit noisey and obviously it is nearly 40 years old so that's my 1st option but are there other things to check?

 

I'm dealing with similar situation in my 78. One the issues. I unplugged the plug from top of fan housing under the hood which stopped the fan from running continuously. Figured I've got all winter to work on it before I'll need a/c. I'm thinking my trouble could be vacuum lines. Hopefully you'll get some replies on here that'll help both of us.

 

My car is a '72 convertible, and so I put in a C4 motor/cage assy, but had to make a 3/4" thick spacer because the C4 squirrel cage is ~3/4" deeper, it has tons of airflow now, but one thing you need to do is get in there with a mirror and a bright light to see how bad the evap coil is blocked with trash/leaves/etc.....it simply has to be cleaned/vacuumed out....I found the best mods beside the C4 blower assy, was that on the ground wire, it's about 12 ga black and goes down to the starter region, and grounds the wiper motor, hi speed blower relay and the blower motor itself of course....that wire needs to be at least a 10 ga, and while redoing all that, I ground it to the intake manifold because quite often that loop gets put on the battery post of the starter, instead to the engine block...

NOW to keep crap outta the airflow, I removed the outside air door in the cowling that sucks air from the wiper area, and trash too...so I release the spring, reinstalled with it glued shut permanently.....using RTV black sealant.....On the pass side, removed the kick panel, and just pulled the flapper door and tossed it, this puts the HVAC system in always recirculation mode,

to facilitate any motor work, just cut out the back section of the fender liner, and then reglue or put a flange on it, and some screws.....my opening is about 8x10 or so.....I did all this back nearly 20 years ago when I bought the car, the C4 blower was done nearly 15 years ago....

 

I saw the c4 with spacer upgrade while searching the site. I definitely will take it apart and see what might be in there. Still not sure what vents the air should be coming from when the fan comes on as I don't really feel it from anywhere. I know the blower is changing speeds as I hear it change when changing speeds with the switch(other than no change from medium to high). I hope there is someother way to access things as I don't see myself ever cutting a section out of the fender liner. I have all winter to play with it so even if it sits apart while I sort it out it can. Thanks for you reply and ideas.