Better AC with different size pulley?

[GoToGuy]

L

Well, I would dearly love to know how to make it blow harder. There's almost assuredly a motor out there that would be better, if we only knew what it was. Being a "squirrel cage" type fan, you can't change that.

Surely we are not the first/only people to want more air out of these...

Vettepilot

You've mentioned a few times about not enough airflow. Do you know if your fan is operating at full RPM. You can test it with cheap electronic tach.
Have you done a search for 12 volt fans. In this day and age it would be easy.
Have inquired with any aftermarket suppliers, Four Seasons, etc. So what results have you turned up? You ask what anybody has found , share what you've got.

 

[L31MaxExpress]

My 99 Tahoe and 99 Express blow hard enough they would probably blow your hat off. My brothers 99 Suburban had excellent airflow as well after we cleaned 15 years worth of junk out of the evaporator core. The 1987 G20 also has excellent airflow after I upgraded the inadequate stock OE wiring, replaced the evaporator core and resealed the underhood box. I need to pull the dash on that one for some interior wiring work and it could stand the ducting resealed while I am in there. I can still feel cool air blowing around behind the dash.

 

[Vettepilot]

L

You've mentioned a few times about not enough airflow. Do you know if your fan is operating at full RPM. You can test it with cheap electronic tach.
Have you done a search for 12 volt fans. In this day and age it would be easy.
Have inquired with any aftermarket suppliers, Four Seasons, etc. So what results have you turned up? You ask what anybody has found , share what you've got.

Well, I am just starting on trying to resolve the problem, and I'm looking to see what fixes others have discovered. As for what I've done:

Apparently PO had installed new evaporator. It looked new, and was very clean. We cleaned it anyway. New, supposedly high quality fan and resistor pack. Wiring and connectors good. We freed up some sticky actuators, and replaced two. The doors all work now. I also plumbed in a heater core shutoff valve. Having a big block of 200 degree heater sitting inside my A/C unit just can't be efficient, so I fixed that.

Imagine my disappointment, when after all that work, the fan on high doesn't put out near enough!

I suppose some small improvement could be had by a complete overhaul of the entire airbox, but that is an incredibly horrible job I would not wish upon my worst enemy. You would not gain much. The fan simply needs to blow harder!! If it's noisy, I'll turn the dam stereo up!!

So, I started my research of the problem here. I can't afford to be a test mule for fan companies, so I need something someone has already found that works.

One expert told me "Good luck--> GM did not figure out a good A/C system until into the 2000's."

There's gotta be something we can do... I hope.

Vettepilot

 

[L31MaxExpress]

I tested the two vehicles I currently have at my disposal to test, the 1987 G20 and the 2011 Pathfinder. Both on dash vent mode, high fan speed and recirculate.I am going to have my mom's 2019 Titan here later, will test it too. I do not think I have seen much over 15 mph from a dash vent in an automobile. Blowing over 10 mph is doing well. I also retested the clutch fan. At 1,500 rpm it is moving about 4,500 cfm using windspeed in front of the grille vs area of the condenser to calculate CFM. I think it would be a more accurate reading with grille off though as the grille does sit 4-6" in front of the condenser and it pulls air from other places.

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[L31MaxExpress]

I have had a 1580386 GM Genuine blower motor sitting in my Amazon cue for about 6 months. Finally bit the bullet and ordered it. Should be here in a day or two. The squirel cage has the same dimension as a normal GM blower motor yet a different part number. It fits some various applications from 1970s through the 90s but I found it interesting on the ~1993 G30 van it is specific to the 15 passenger models. Something tells me it is a higher CFM unit, perhaps spins more rpm. It will be quick to throw in and do some testing. The blower currently in the van has the stock 87 GM wheel and was a 20 year old new aftermarket Siemens motor I had laying in my stash of spare parts. I am hoping the GM blower makes it blow even better like a new GM blower did on my 1997 Express. Switching from an aftermarket blower to a GM Genuine blower that GM puts on the late model Express practically doubled the force and CFM. I thought it was blowing a bit weak, but had no idea how weak until I swapped the blower.

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[Vettepilot]

Interesting. I'll be waiting to hear.

So the #1580386 is the one you're testing??

Vettepilot

 

[Vettepilot]

Well, mine is GM genuine.

I don't know...

This is it:

Vettepilot

 

[L31MaxExpress]

Interesting. I'll be waiting to hear.

So the #1580386 is the one you're testing??

Vettepilot

That is correct. 15-80386 is the one I will be testing.

 

[JohnZ71]

Hmm… the one I ordered for my Tahoe last year is GM 15-80665. What’s the difference?????

 

[L31MaxExpress]

Hmm… the one I ordered for my Tahoe last year is GM 15-80665. What’s the difference?????

My aim is to find out. The 15-803886 is listed to fit the 80s S10 Blazer/Bravada, a 1978 Sunbird and a 1985 Cadillac as well as a 90s 15 passenger G-van.