Electrical Guru's, Blower Motor Speed Question
Thread Starter
Racer
Joined: Apr 2016
Posts: 494
Likes: 93
From: Bucks County PA
Electrical Guru's, Blower Motor Speed Question
Hey everyone.
This isn't actually a Corvette related question, but out of all of the forums I belong to, I think this Corvette Forum may have the best knowledge base, more DIY people etc.... (or at least some very good opinions). I'm guessing that this could also possibly help others in the future as it seems most people here seem to be hands on and possibly some have considered this as well).
This has to do with Heater / AC blower motor / speed control question.
Most everyone here knows that "in the good old days", the Heat/AC blower fan's speed was controlled by a "good old resistor pack". Low, Medium and High settings that, for the most part, was a good simple system that has worked since the "beginning of time".
As the years went on, computer controlled HVAC systems came along. (Along with bunch of new and exciting computer and electrical issues that could leave your blower fan inoperable, difficult troubleshooting and an expensive fix)
.
I'm working on a Chevy Truck / 4x4 Winter / Mud Truck / Project with (hopefully) very minimal electronic / computer control as far as the HVAC operation, and I have a question for the Electronic Guru's in the crowd here. (I actually have a degree in electronic engineering from waaaaaay back in 1989 so I have a fairly firm grasp (albeit a little rusty, since I've been a Real Estate Broker for the last 18 years....
)...
Can someone help me (and possibly others with this):
On the newer vehicles, that use the digital type of HVAC Controls, I'm seeing (at least on my BMW, newer Chevy Truck, the use of a Pulse Width Modulation (PWM) Speed controller for the HVAC Fan Motor(s).
Some specifics:
Right now, the existing blower fan circuit is fed by a 30AMP Fuse. The wiring for the fan is fairly simple and straight forward.
The existing fan motor pulls slightly less than 20Amps on High Speed, and slightly lower on all lower speeds, which range from 10% of max speed and adjustable all the way up to 100% speed. (Current may surge at turn on a bit, but I don't see much of anything in the testing that I've done).
The Factory PWM is an expensive / trouble prone etc / unnecessary for what I'm doing here (and is currently inoperable).
(All of the "Dual Zone Heating / Cooling is currently removed).
Right now I have a very neatly wired and functional (right out of the original fuse block and factory wiring harness etc), SINGLE SPEED (HIGH) blower fan operation. (Which is actually fine and I may leave it that way). I was thinking today about:
Looking for an inexpensive "Generic Type" of PWM DC motor Controller. I've seen a few with 2-5 "preset" speeds , but for the most part, they are all adjustable via a small control ****.
For the guys that do this thing all the time. Is something like in the link below suitable for this application???
I've seen numerous online for use with applications from 10-50 Volts DC and various configurations 10amp, 20 amp, 50 amp etc.
Even though my existing circuit is 30 amp and the motor is currently pulling about 20amp, my gut would say go with a 12volt / 30amp controller.
My Questions:
Would going with a 40amp controller be a safer bet? OR with a system like this, would it not be advised?
PWM CONTROLLER LINK:
http://www.ebay.com/itm/9-50V-40A-DC...IAAOSw6EhUT07D
Last question:
Is a controller similar to the one above suitable for an application like this at all?
It appears to me, they would but I'm just not sure. Any info would be a huge help. Variable speed, while not totally needed, would be nice (especially if I don't need a $250 failure prone factory PWM / controller..
This isn't actually a Corvette related question, but out of all of the forums I belong to, I think this Corvette Forum may have the best knowledge base, more DIY people etc.... (or at least some very good opinions). I'm guessing that this could also possibly help others in the future as it seems most people here seem to be hands on and possibly some have considered this as well).
This has to do with Heater / AC blower motor / speed control question.
Most everyone here knows that "in the good old days", the Heat/AC blower fan's speed was controlled by a "good old resistor pack". Low, Medium and High settings that, for the most part, was a good simple system that has worked since the "beginning of time".
As the years went on, computer controlled HVAC systems came along. (Along with bunch of new and exciting computer and electrical issues that could leave your blower fan inoperable, difficult troubleshooting and an expensive fix)
.I'm working on a Chevy Truck / 4x4 Winter / Mud Truck / Project with (hopefully) very minimal electronic / computer control as far as the HVAC operation, and I have a question for the Electronic Guru's in the crowd here. (I actually have a degree in electronic engineering from waaaaaay back in 1989 so I have a fairly firm grasp (albeit a little rusty, since I've been a Real Estate Broker for the last 18 years....
)...Can someone help me (and possibly others with this):
On the newer vehicles, that use the digital type of HVAC Controls, I'm seeing (at least on my BMW, newer Chevy Truck, the use of a Pulse Width Modulation (PWM) Speed controller for the HVAC Fan Motor(s).
Some specifics:
Right now, the existing blower fan circuit is fed by a 30AMP Fuse. The wiring for the fan is fairly simple and straight forward.
The existing fan motor pulls slightly less than 20Amps on High Speed, and slightly lower on all lower speeds, which range from 10% of max speed and adjustable all the way up to 100% speed. (Current may surge at turn on a bit, but I don't see much of anything in the testing that I've done).
The Factory PWM is an expensive / trouble prone etc / unnecessary for what I'm doing here (and is currently inoperable).
(All of the "Dual Zone Heating / Cooling is currently removed).
Right now I have a very neatly wired and functional (right out of the original fuse block and factory wiring harness etc), SINGLE SPEED (HIGH) blower fan operation. (Which is actually fine and I may leave it that way). I was thinking today about:
Looking for an inexpensive "Generic Type" of PWM DC motor Controller. I've seen a few with 2-5 "preset" speeds , but for the most part, they are all adjustable via a small control ****.
For the guys that do this thing all the time. Is something like in the link below suitable for this application???
I've seen numerous online for use with applications from 10-50 Volts DC and various configurations 10amp, 20 amp, 50 amp etc.
Even though my existing circuit is 30 amp and the motor is currently pulling about 20amp, my gut would say go with a 12volt / 30amp controller.
My Questions:
Would going with a 40amp controller be a safer bet? OR with a system like this, would it not be advised?
PWM CONTROLLER LINK:
http://www.ebay.com/itm/9-50V-40A-DC...IAAOSw6EhUT07D
Last question:
Is a controller similar to the one above suitable for an application like this at all?
It appears to me, they would but I'm just not sure. Any info would be a huge help. Variable speed, while not totally needed, would be nice (especially if I don't need a $250 failure prone factory PWM / controller..
Last edited by 76C3forme; May 30, 2016 at 12:02 AM.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
Man, my eyes got tired from reading your very thorough post...
Sure that controller will work. For that cheap price its a bargain. Say thanks to China...Its possible that your amp meter is getting confused when trying to read pulses instead of continuous DC. Worst case the controller should have some type of self protection current limiting. Reading their ad they even have higher modules available, 40A is fine!
Or you could try a ENGINE fan controller, they use even higher amp motors
I have repaired some bi polar fan controllers, usually the pass transistor goes bad because they run really HOT. But your idea of a generic PWM unit is way better
Sure that controller will work. For that cheap price its a bargain. Say thanks to China...Its possible that your amp meter is getting confused when trying to read pulses instead of continuous DC. Worst case the controller should have some type of self protection current limiting. Reading their ad they even have higher modules available, 40A is fine!
Or you could try a ENGINE fan controller, they use even higher amp motors
I have repaired some bi polar fan controllers, usually the pass transistor goes bad because they run really HOT. But your idea of a generic PWM unit is way better
Last edited by mikem350; May 30, 2016 at 09:02 AM.
Thread Starter
Racer
Joined: Apr 2016
Posts: 494
Likes: 93
From: Bucks County PA
Man, my eyes got tired from reading your very thorough post...
Sure that controller will work. For that cheap price its a bargain. Say thanks to China...Its possible that your amp meter is getting confused when trying to read pulses instead of continuous DC. Worst case the controller should have some type of self protection current limiting. Reading their ad they even have higher modules available, 40A is fine!
Or you could try a ENGINE fan controller, they use even higher amp motors
I have repaired some bi polar fan controllers, usually the pass transistor goes bad because they run really HOT. But your idea of a generic PWM unit is way better
Sure that controller will work. For that cheap price its a bargain. Say thanks to China...Its possible that your amp meter is getting confused when trying to read pulses instead of continuous DC. Worst case the controller should have some type of self protection current limiting. Reading their ad they even have higher modules available, 40A is fine!
Or you could try a ENGINE fan controller, they use even higher amp motors
I have repaired some bi polar fan controllers, usually the pass transistor goes bad because they run really HOT. But your idea of a generic PWM unit is way better
(I do tend to run on with my posts!!, but I think that's a habit I got into after reading posts that never have enough info for people to help)..
It's funny, While looking online, I did start thinking about the possibility of using an Engine Fan Controller. (Just like you say, they function with higher amp motors).
I agree with you on the transistors burning up. On our 2002 Saab 9-3 convertible the fan controller is fairly prone to burning up the Mosfet inside as well. (Haven't needed to repair it yet, but I'd give it a shot...)
Since I've been out of the field for quite some time and the PWM controllers came along later on, I just wasn't sure if one with a higher amp rating would be ok / or be overkill / or if it should be sized fairly close for the application. I guess my "default thinking" with a higher current application, would be to always "appropriately oversize" components to play it safe. (Other than the fuse of course!).
Thanks Again, I think I'm going to give that a try... Thanks for the info... Although they are fairly cheap, I didn't want to buy one if I was way off base for the application.....
And actually, I happened to see this one:
http://www.ebay.com/itm/DC-10-50V-40A-Motor-Speed-Control-PWM-HHO-RC-Controller-12-24-36-50V-2000W-MAX/191862639900?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36892%26meid%3D5df81fb3f997420f84aff849b44fd20f%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D371175245087
This appears to be (unless it's a typo) 200khz vs the other one that is 12khz.
Even if it's a typo and it should be 20khz, I was wondering if there would be any hum / noise with the 12khz PWM. Looking online, I see a few others that are experiencing some hum when running and a few suggest units over 19khz / out of the audible range would be better. I have to admit, I didn't even think of that.
I may have to wire an On/Off switch as some of these units have a low setting of about 5%-10% of fan speed (variable up to 100% speed). Without a switch my fan may run constantly since the original fan control circuit is powered even when the ignition is turned off. (Not quite sure why they designed it like that, versus having the circuit powered on only with the ignition / accessory circuit...
I like the detached variable control of the first link I posted (Emailed to see if there was any off/on function, but the 2nd link @ 200Khz may work better. Looking online, that type seems to have an off/on function but the variable control is attached. (but I'm sure removing it and extending it would not be an issue if I wanted to..)
Last edited by 76C3forme; May 30, 2016 at 05:25 PM.
