I think you may be right about the A bodys vent setup. I put a stronger blower motor in my 69 GTO. On the bench it spun much faster but when installed it sounded like it was blowing a lot of air but no difference at the vents. I think the way the air is routed is very restrictive and just wont pass a whole lot more air.

I flushed the debris as best I could from the evaporator and sealed everything I could find including the plastic inside AC plenum. I blocked off the two lower air outlets and went with just the L an R balls and the center outlet. I am running a newer blower motor with factory metal impeller. All speeds are functioning correctly. I was rather amazed at the improved output of air. Left ball, 130 to 140 mph, Right ball 110 to 120 mph, Center outlet 90 to 100 mph. I used this air flow meter placed right up next to the outlet.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Better strong blower motor for factory a/c cars
 

Bringing this old thread back up because I tried what "70455HOVert" talks about in post #'s 16,17,18,21 & 23 (5/20,21 & 23 2016) on my '69 GTO w/factory a/c. I used the GM motor 158535(52466066, 52498870) for the '95 Chevrolet Astro Van w/auxilliary rear A/C instead of the VDO/Continenal PM136 from Rock Auto like 70455HOVert did. Wish now that I would have went with VDO because he talks of blades being bigger and more curved than what our cars use and the fan on the GM motor I bought was similar to our OEM fans, BUT the motor does spin faster (and my my measurement draws less amps than the factory replacement motor). It's a definite improvement in velocity and volume of air flow out vents but, not the"hurricane" that 70455HOVert speaks of (BUT to his credit he used the VDO PM136 motor and if the picture on Rock Auto is accurate the blades on fan are bigger and more curved than the GM motor that I bought from Rock Auto). I would definitly recommend this substitution when replacing blower fan motor. As 70455HOVert says, it's a direct bolt in. The motor is little shorter therefore the cooling hose (from air box back to blower motor) fits with a little tweaking but in my case original hose was so rotten from being 52 years old that it ripped and I had to make one from 5/8" clear plastic tubing but no big deal.

Check this out:
https://forums.maxperformanceinc.com/forums/showthread.php?p=6144995#post6144995

It appears that he bought a Four Seasons 35383

It looks like the 35383 has black blades and Scarebird bought the Four Seasons with clear blades like or 35344 (front w/ wheel) or 35333 (rear with AC / CCW).

The plot thickens...

Better stronger blower motor for A/C cars
 

Check out my post (#43) on this thread along with post #'s 16,17,18 & 21 by "70455HOVert". He did all the research back in 2016 I just followed his suggestion except I went with GM158535 (52466066, 52498870) thinking it would be better at $52.00 than the VDO/Continental PM136 recommended by "70455HOVert" in his 2016 posts but, if you look at picture of VDO PM136 by clicking "info" in description line on Rock Auto you can see the fan blades on it look much wider and more curved than our OEM's on these cars, (which is what he says in his post). (1995 Chevrolet Astro Van with rear auxilliary A/C on Rock Auto is where I looked). As I said in my post (#43), the GM 158535 I used is big improvement in velocity and volume of air coming out vents on my 69 GTO but no "HURRICANE" as 70455HOVert describes as being his result with VDO/Continental PM136, which by the way is only $19.00 at Rock Auto.

My bad. It must be the 35333.

IIRC, the 35333 unit is CCW. I'm assuming this would make a difference?

69 Limelight...you mentioned "the cooling hose (from air box back to blower motor) fits with a little tweaking". Are you talking about 5/8" heater hose like this...https://www.opgi.com/fittings-hoses/hose-line-clamps-brackets/heater-hose-set-original-style3/hose-set-heater-ribbed-1959-87-gm-ch20253.html

Better stronger blower motor for factory A/C cars
 

No not hose like that. Your car should have a factory molded short (about 4") hose that connects from a fitting on your air box forward of your blower motor and connects to blower motor to help keep windings cool. If your factory hose is in good shape it will fill VDO PM136 or GM 158535 but since theses motors are a little shorter than the factory OEM motors the hose has to have the molded bend bent a little more. My hose was original and rotten (52 years old) and when I got it installed it split. I went to a farm supply store and got a length of clear plastic thin wall tubing/hose that they use on pesticide/herbicide spray rigs (multitude of other uses for tubing) (plumbing stores have it too) and it worked perfectly. Just heated it a little with heat gun so I could make bend and it would stay bent and not kink. I really urge you to go back on this thread and read "70455HOVert" 's posts on this improved motor swap (post #'s 16, 17, 18, 21 & 23). He did the research work on this and explains how well it worked. Once again I urge you to use the VDO PM136 motor like he did instead of the GM158535 motor like I did. Although I'm satisfied ,with my increased velocity and volume, from "70455HOVert" 's description of his results with the VDO PM136 motor and once you look at picture of cage/fan on Rock Auto's site of VDO PM136 you will see it's got to move a lot of air plus it's like $19.00 and the GM I bought for same original application was $53.00.

I think I'll just order the PM136 for giggles. Since it's only $19, not much lost.

I was thinking to add some/the hose to the order to make full use of the shipping charges, but not sure what part # (or other) would work. Any ideas??

Better stronger blower motor for factory A/C cars
 

I think that's an excellent decision and I believe you'll be pleasantly surprised with the new performance of your A/C. Please post some pictures of that VDO cage/fan and measurements of blade width. I sure looks like wider more curved blades in Rock Auto photo. Who knows, it may have more blades than the factory OEM too. Don't get hung up on that hose. It's only about 4" long and there are lots of possibilities. I just used that clear/thin wall plastic tubing because that's what came to mind and readily available at my farm supply store and plumbing store. You may have your old OEM one laying around. It will work fine if not rotten from old age like mine was. I just couldn't find a reproduction in Ames or OPGI catalogs or on e-bay. Keep us posted.

I just ordered one too, have no idea if it will work on my 68 GTO ... but when people say good things about something that costs $19 I just can't help myself.

My restoration is kind of going to opposite of the direction of many people. Pretty much absolutely stock performance but I want I the car as "Luxury" as it was when I bought it in 1976, all the comfort stuff working perfectly. Cold, quiet and smooth.

I don't think looking for larger or more blades is the best way to choose the fan to buy. If the motor on the one with the largest and most blades is lacking on power, it might get dragged down in speed more. Possible for a fan with a more powerful motor to out flow another even if it has less blade area. The only way to do it accurately would be to buy them all and test them against each other. Same with a sharper angle. Blade design, motor speed and power should be engineered together for the best performance and efficiency.

Just messed with the PM136 on the bench. Hooked it up to a variable power supply. Not sure how it works when encased in the blower housing ... but jeez, on the bench I can't imagine it being much more powerful without being scary :)

Ran it at 12v, was drawing about 5.5 amps, so about 66 watts. Running at that rate it could probably use a tad of balancing. Might pull the fan off and see how hard it is to balance.

Sounds like a good indicator so far. Can you easily swap it in your housing and do back-to-back tests comparing it to the original motor?
Also, if you are able to run it at 14 volts, it would simulate better how it will perform while the engine is running. I think you would notice the difference in the air movement.

Seems like trial and error would be the only method to try and balance the fan. Maybe a small U-nut would work if you can make it fit tightly.
Also seems like you might be able to hold the motor in a vise and check with a dial indicator to see if the fan has any runout to it when turning it by hand.

Anyway, thanks for your reporting on this. It helps me out since I intend to make a decision on this soon.

Better stronger blower motor for factory A/C cars
 

Hey Dataway, would you mind posting a picture of the PM136 fan alongside the standard factory fan and measure the width of the blades on PM136. Like I said in one of my above posts, I went with GM158535 for same application as PM136 and although it has more volume and velocity out vents than standard it is not a "hurricane" as 70455HOVert describes the PM136 in one of his above posts from 2016. I wish I would have went with PM136 but thought at 2 1/2 times the price the GM would be a better quality unit. Thanks.

I will do some further examination and experimentation this evening and report the results.

Here are some photos of an OEM 68 motor and fan, and the PM136.

Fans are pretty much identical in dimensions, just one plastic, one metal. Vanes on the PM136 appear to be a bit more engineered than the standard squirrel cage vanes on the OEM unit. The OEM vanes are slightly hidden behind their flange so the PM136 may look a tad wider but they are pretty much the same. Both about 2.75" tall. PM136 cage is about 1/8" smaller in OD. The OEM motor is about 1" taller than the PM136 ... the PM136 has the motor countersunk into the mounting plate ... which is why the OEM vent tube doesn't fit right.

My 10 amp 0-30 vdc power supply doesn't seem to have the nads to run them full speed so I was testing with a 12v battery. My quickie power meter setup gave inconsistent results. I can say that the OEM unit shows 0.7 ohm across the contacts, and the PM136 shows 0.3 ohms ... which would lead me to believe it is higher wattage. However they are different types of motors, the OEM motor is the free spinning old school DC motor we are all used to, the PM136 has a motor that has that notchy feeling as the poles pass each other ... like I've felt on more modern motors .... I don't know much about motors so maybe someone else knows what this means.

Since differences in the electrical specifications are probably of less interest than how they perform I'm going to try to test them in the housing with a wind speed meter and a manometer to see if I can determine which one "blows" more :). I have an AC/Heat housing with the cores still installed, maybe I can measure which one moves more air.

I think that notchy feeling means it's a stepper motor which is a brushless design. The OEM would have brushes. A brushless motor should give a much longer service life.

Yep ... it feels like the motors in drones and very much like the motor in my Milwaukee variable speed die grinder.