Front HVAC Blower - Need More CFMs!

[caw_86]

I mention two effects:

- torque increases with increasing current
- torque increases with decreasing speed

I may have caused confusion by inserting that graph of torque vs. speed, but they're intimately related.

Unfortunately this kind of experiment would require a lathe, which i do not have access too

 

[The_Full_Monte]

Thanks for all the input, guys! There is definitely some air leaking behind the dash. In the places that I can fit my hand behind the dash, some places have cold air moving "quickly," not just cold air radiating from the HVAC box.

 

[Wildblue19]

If you have an anemometer you can reference vent speeds as shown in my thread here. I have the same issue, rear blows better than the front.

 

[L31MaxExpress]

I wonder how long a standard blower motor would live on 19 volts...16 volts used to be a common upgrade for racers seeking added power for electric water pumps, electric fans, and ignition systems. They ran a 3 post 12/16 volt battery and a DC to DC converter to charge and operate the 16 volt side of the system.

I might have to pick one of these up and supply 19V to the higher blower relays power input for testing purposes.

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[1998_K1500_Sub]

I wonder how long a standard blower motor would live on 19 volts.

I might have to pick one of these up and supply 19V to the higher blower relays power input for testing purposes.

That power supply wouldn’t have the mojo it takes to operate a blower motor at 19V, by my estimate.

I posted here (link below) my S10 blower's current draw, which was ~16.3A on high with engine off. I didn't measure the voltage across the motor terminals in that particular case but I would guess it to be ~11.5 or less, and so the delivered power was around 180W. I did make other measurements, where I noted both the voltage at the blower terminals and the resulting current draw, and I graphed the results.

Note the graph in my post. The blower current increases as a second-order function of the voltage, and using the data given there I would estimate, for 19V applied to the blower terminals, the resulting current to be around ~41A, and the power delivered to the blower around 790W.

My guess is the motor windings would to take on a dark, smoky patina after a short period of time if one applied 19V... but I could be wrong.

Let's not forget the brushes and commutator...

See
https://www.gmt400.com/threads/hvac-blower-motor-resistor-replacement.59076/post-1256780

 

[bretcopsey]

I can tell by the contents within this thread that the level of knowledge and understanding of electrical theory etc. far surpasses mine, so I mean no offense…

I replaced the blower motor in my son’s 96 ECSB and found it incredibly easy the mistakenly reverse the polarity when I reconnected power. For a couple of moments I was perplexed when I got everything back together and the fan worked appropriately through the various speed settings but was barely producing any output from any of the vents. I switched the wiring which changed the fan rotation and problem fixed-sometimes the simple solutions are easy to overlook. Even if this doesn’t help OP maybe it will help someone else searching later. Carry on

 

[Jeepwalker]

I didn't read every word in this thread, but did you verify all the damper doors are closing properly? Can you drive them open/closed with a scan tool? Or just remove the actuator and use a tool/implement....

 

[Eveready]

Have you made sure that the core isn't plugged up with many years of crud? The lack of a cabin filter has been the subject of much discussion here and the directions for cleaning one out are buried in several threads. My apologies if you have replaced it. I haven't read the entire thread.

 

[The_Full_Monte]

Have you made sure that the core isn't plugged up with many years of crud? The lack of a cabin filter has been the subject of much discussion here and the directions for cleaning one out are buried in several threads. My apologies if you have replaced it. I haven't read the entire thread.

Yes - front and rear heater cores have been replaced, and front and rear evaporator coils have been thoroughly cleaned and inspected every year.