anyone try putting a 79 a/c blower in a early c3? would it be worth the time in modification?

 

The fans are the same size if my memory serves me correctly.

But you writing "early c3"..I can only assume you also have A/C.

I know that you can space out the blower motor about one inch and use a 1984 to 1996 fan...but I honestly do not know if that helps because you are only spacing out the blower motor...and this is not changing the actual case depth. So...when you are done doing this...you can see that that one inch of spacer is really not allowing much if any more air to get in.

I have an air flow meter but have not yet performed a test to see if there is a difference if this modification is done. I have air flow readings on new blower motors with new evaporator cores, etc....but I have not yet converted one to see if there is a change/increase.

And I have not tested to see if the 1984-1996 blower motors actually turn faster.

DUB

 

my 73 has a/c. i have a extra blower thats longer. i figure it would blow faster/more air. when i look at vette catalogs i see two different part number 63-77 and 78-82. maybe my extra blower is c4 but its definitely longer.

you wouldn't try this mod? or find it worth the trouble?

 

I believe the L.77-82 fan motor turns at a higher rpm, and the fan may have a pitch difference. Having all the duct work in the correct location and well sealed, mode door adjusted to fully close (bias to the A/C side) . makes a tremendous difference in the air flow. This surprised me.
Forgot, a clean evaporator core.

 

The usual way to get more air from a C3 HVAC system is to use aC4 fan/squirrel cage. You can use either a C4 or a C3 motor. The fan is approx. 3/4 inch longer than a C3's, so you need to shim it out when installing. A Search will get you more info.

I have a C4 fan (on a C3 motor, all left over after I installed a Vintage Air system). PM me if you are interested.

 

Don't bother... get a wheel from a C4 or get the blower wheel and motor if you like , but the C3 motor will work just fine. . space your motor out 3/8 of an inch for the new wheel.. it is much longer, and there is a lot of wasted space behind the short c3 wheel. .... and feel your hair move from your center vent.. I did mine long ago... My car is black and its HOT! here.. needed more air. Its a big difference . think 30-40% more air flow ....by the way, you can get the blower wheel from Amazon for under $20 Four Seasons Brand

 

The C3 blowers had no problem blasting air out the vents when new. Odds are that the blower plenum has filled up with leaves, pine needles, small twigs, mouse lair junk, whatever....and the air passage is partially blocked. Before you go to the trouble/cost of replacing that blower, remove it and clean out that plenum first. Another possibility is that the air inlet door (under the right-side cowl area) is NOT opening for some reason. In either case, replacing the blower will not improve your situation.

P.S. The replacement blowers you get at the auto parts store have NOTHING like the electrical innards of the stock blower. If you do need to replace it, try to find an EQUIVALENT blower (or better), and not one with shi++y wire, etc like produced in China which LOOKS like a C3 blower.

 

I replaced my 77 C3 blower with an 84 C4 blower and the difference is significant. The C4 blower wheel is longer but I believe most of the benefit comes from the pitch of the blades on the wheel.
There were no obstructions in my plenum or in the ducting it was purely a function of the fan not being effecient enough to push the cold air.
Cold air is harder to push than warm air. This makes the fan's job harder. on heat I'm sure we all find the blower adequate but on A/C, not so much.

My new C4 blower blew so hard that it blew much of the duct sealing foam out of the ducts. It was old and crumbled so needed replacing in any case.

I got the China junk replacement fan and motor assembly. First blower wheel disintegrated after about 30 seconds. However I suspected that it would happen since the blower wheel did not run concentrically even at the parts store. Second one has been in there for 3 years with no problems.

 

so how did you adapt it?

 

I used a piece of marine plywood as a spacer and sealed it with POR15 to further seal it and protect from moisture. The plastic squirrel cage fan from a C4 is the same diameter as your metal C3 fan. It is just longer and has many more blades, with a more precise angle/contour than the stamped C3 fan.

If you need a C4 fan, with or without a C3 fan motor, PM me. It worked fine, but I finally changed everything out for a Vintage Air system.

 

I took everyone's advice years ago, cut out the fender liner in back pass side, pulled the motor/fan the easy way, got into the evap housing with a strong shop vac and cleaned it out good, while I at it, I pulled the door behind the kick panel on pass side, and pulled the flapper door, released the spring, and put it back in place with RTV, sealing that cowling input/fresh air intake....my '72 is a convertible...fresh air not needed...ya THINK?? used 3/4 ply for the spacer and put in a parts house C4 blower, thing blows more air than a frat party......



edit, also that ~12 ga wire going to the starter area, it's the ground for the blower, and the wiper motor and high speed relay, I increased it to a full 10ga+ wire and ran it to the intake manifold gets full voltage to the motor, also took a heavy wire from the alternator to the high speed relay...to ensure full system voltage at the blower.....

 

I laminated a couple pieces of plywood together to get about 7/8" or so of thickness. Then I coated that with truck bed liner spray so moisture would not penetrate it.
I also increased the ground wire size to 10 gauge.

I did have to "clock" the rear of the motor to get the cooling hose for the motor to fit correctly. Involved taking the bolts out of the motor that hold the rear housing on and rotating it to re-position the cooling hose connection.

That job was a back killer due to the fan's location and kind of a PIA but worth it in the end.

 

If you have an A/C car from 1970-72 model years, you can remove the side vent from the fender and get to the blower that way. It is easier.

You may need to 'adjust' one of the A/C pressure lines a bit to get clearance. You can just crack the hose joint retaining nut (just enough so that you can rotate that line but NOT lose sealing capability) and rotate line to provide a bit more opening for blower removal. Then clamp in down in that new location. If you do lose a slight bit of refrigerant, it won't cause you any problems.

Most likely causes for 'weak' blower airflow:

Debris in plenum; inlet air door closed (if you seal this door closed, you can still get "Recirculated" airflow...but that limits it to air inside the cabin--NO outside air); poor power line connection; poor ground connection; defective blower motor (note that this is the LEAST likely condition).

I strongly suggest that you check/correct any of the Top 4 reasons for such problem before you change blowers. There is no doubt that upgrading the blower will get more airflow...but chances are that the electrical improvements made during that change really fixed the original problem.