71-74 B-body Blower Motor Weak Airflow

Guys,

I have another thing I have been grappling with over the past two years on my Charger but I have been preoccupied with more important issues but I am working around to some of the more minor thing.

The car is a 1973 Charger with A/C. The HVAC box is fully restored with a new blower motor. Every since day one this has had wimpy airflow. As in a "low" you can barely feel airflow and "high" is about like the lowest setting on my daily driver.

I have checked to make sure the vacuum pots and doors are all opening and they are. Blower motor is getting 14V on high and I know it's not wired backwards (I tested). The blower motor is the standard A1-cardone Autozone special.

Is this normal for the 71-74 b-body heater boxes? I didn't think they would be necessarily be up to snuff compared to a new car but this seems really wimpy. I hate it because the A/C is nice and cold but loses the battle on any hot day because of the poor airflow.

IS there anything else that could be wrong? Are these reman parts-store motors just that bad or is this just how there were?

Any ideas where I can go from here? Any ideas are appreciated...I am loving this car now that it's running well but I put all this $$$ into the A/C and I really hate that it can't keep up on a 80*+ day.

Thanks!

I'd take the mtr out & jump right to it from the batt positive/neg posts to see if it kicks out good air as opposed to potentially being a duct/low voltage/grn continuity/housing drag on impeller issue

blower motor resistor? bad cardone blower motor?

I pulled the motor and bench tested it. It seems to spin pretty good and move air for sure. Can anybody confirm if the blower wheel is installed correctly and turning the right way?

I don't see any evidence of the wheel rubbing on the housing or anywhere and I can guarantee the dash ducts are all perfectly clean with no obstructions. I tore down the entire dash, scrubbed out the ductwork, and even sealed the seams where it was stapled together.

The resistor also isn't an issue as high setting bypasses it entirely and it steps down on low and medium like it should.

Do you have another pic of the other side? Looks like it may be backwards to me.

Here you go.

Fan is mounted on the shaft backwards.

Yep, the opening on the inside needs to face away from the fan motor, that's where it draws the air in to send out and that is why it's weak, you are blocking most of hte opening.

Ok so I have the blower wheel on backwards? I can't seat the motor all the way in the housing with the wheel on opening facing away from the motor. It is about 1/4" too long and hits the inside of the housing from what I can tell.

The only thing I can think off is that this wheel is from a 1973 hosuing (my original) and the front half of my box was from a 1971 Satellite as my original front was cracked bad. I thought the 71-74 HVAC boxes were interchangeable in every way pretty much?

Did the 71 years have a thinner wheel than the 73's did?

EDIT: Yeah I just reversed the wheel on the shaft and the blower is about 1/2" from being able to go all the way in...what gives??

Where is the fan to housing gasket & spacers? Should be in place before the fan is installed on the shaft. There is at least 1/2" of depth adjustment on the shaft, are you sure the fan is positioned as far down the shaft without contacting the motor?

I have the gasket but I am not aware of any spacers? Can you elaborate on these or do you have a picture of them? Spacers would make sense here to back the motor out from the housing...

Yes, the wheel is bottomed out on the shaft...can go no further.

With the gasket & spacers, would set the motor out maybe 1/8-1/4”, sounds like something else may be a miss.

Something doesn’t look right with your motor, could the mounting plate be installed on the motor backwards? Wrong aftermarket motor? IIRC, shouldn’t be able to install the fan wheel backwards.

Thanks for all the advice and help. I think I may have figured this out since you guys confirmed that my wheel is on backwards.

When I search for my motor on various sites (Rockauto, Advance, AZ, Ebay, etc.), I see two motors coming up. The one I have is this one:




If you can see the motor is protruding into the housing and could account for this fitment issue. I noticed another style without the protruded motor which looks much more like the factory:



I see on these sites that these two styles are classified as either 71-74 E-body or 71-74 B-body depending on which site you look. I think I have a motor for an E-body right now. I went ahead and ordered the "flat style" and we will see how it works!

Good to see these motors can be had for around $30 with free shipping. Might be the only thing that doesn't cost an arm and a leg for this car!

Hey guys,

Thanks for all the help. I got the new motor in yesterday and got the pigtails moved over. I dropped it in and problem solved! My A/C can make that car freeze now.

I should have figured that what I had wasn't normal. Foolishly I saw that 2 or 3 of the parts sites listed the same motor I had but I guess they were wrong!

Thanks again!!

Do this.

http://www.dieseltruckresource.com/forums/1st-gen-ram-all-topics-93/blower-motor-158400/

It just might surprise you.

Those trucks use the same setup as the old cars so you will likely find the same benefit.