chevyuser74
1/2 ton status
anyone know the difference between blower motors a/c or non a/c besides the bolt pattern. do they blow harder fan bigger?
CK5
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blower motor?
- Thread starter chevyuser74
- Start date
Slightly bigger motor on the A/C version.
A/C version has taller wheel, blows more air.
You cannot fit A/C wheel in non/AC case, it won't go all the way in.
You can press/bolt (depending on year) the non a/c wheel onthe ac motor, you should change your resistor then to get the most out of the motor.
For a twist, there's the heavy duty heat option. Has slight larger diameter wheel, but same depth as std. heater non-ac, and has same motor as AC. This option has a different case on the firewall for the larger diamter wheel.
A/C version has taller wheel, blows more air.
You cannot fit A/C wheel in non/AC case, it won't go all the way in.
You can press/bolt (depending on year) the non a/c wheel onthe ac motor, you should change your resistor then to get the most out of the motor.
For a twist, there's the heavy duty heat option. Has slight larger diameter wheel, but same depth as std. heater non-ac, and has same motor as AC. This option has a different case on the firewall for the larger diamter wheel.
Are you certain the HD fan is larger diameter?
Not arguing, I've got the HD fan setup myself, but the only thing I noticed that was really different is that the case has the cooling port for the blower motor itself, just like the AC motors.
On high, I believe there is no resistance to the power going to the blower motor. My dad put an AC blower motor in his non-AC heater box, it definitely works as effectively as my HD heater setup. The controls are a bit different as well, as the HD has two off positions...one on the fan switch, one on the upper sliding lever. (I think thats the heater/defrost select one)
My understanding of electric motors tells me that the AC/HD motors are wound differently, resulting in higher rotational speed. Might be a good idea to put some sort of filter over the hole on a vented blower motor if running it in a non-AC/HD box, but my dads been running his for years (granted, not much use, and not in much mud) with no filter, just the open hole.
Not arguing, I've got the HD fan setup myself, but the only thing I noticed that was really different is that the case has the cooling port for the blower motor itself, just like the AC motors.
On high, I believe there is no resistance to the power going to the blower motor. My dad put an AC blower motor in his non-AC heater box, it definitely works as effectively as my HD heater setup. The controls are a bit different as well, as the HD has two off positions...one on the fan switch, one on the upper sliding lever. (I think thats the heater/defrost select one)
My understanding of electric motors tells me that the AC/HD motors are wound differently, resulting in higher rotational speed. Might be a good idea to put some sort of filter over the hole on a vented blower motor if running it in a non-AC/HD box, but my dads been running his for years (granted, not much use, and not in much mud) with no filter, just the open hole.
Yes, I'm sure.
The trouble is, the parts books at various parts stores for this part, including AC Delco, is flat out wrong. I know. I researched this very item. If you look in the GM parts books, there are different numbers for the blower wheels. The no-ac, HD heat one is separate, same height as std heat, but slightly larger diameter. The HD heat also takes the same motor as AC equiped trucks, if you look carfully, which, as you mention, also has the little cooling tube to help keep the motor cool. When I ordered various GM part numbers from anyplace I could find the real GM parts, they all came, and you can then see the differences. There are three wheels (actually 6). STD heat, HD heat, and AC with or without HD heat. The reason for 6 is somewhere in the mid-80's GM changed to press-on wheels & motors, as opposed to bolt on. The aftermarket wheels come with an allen set screw which will adapt to both.
BTW, if you order the aftermarket std heat no-ac wheel, it's slightly less tall than the OEM version, as if the blower and wheel already couldn't keep the windshield defogged on a rainy day, do youself a favor, and find a wheel from a junkyard if you need one.
I looked up and ordered (found a dealer out west that had it stock) the metal case that goes on the outside of the firewall for the no-ac HD heat version. The case will accept a larger diamter wheel. Mabey it was only the pre'80's version, there were some differences there as well.
The switch in the dash is also different for HD heat, as you mention. The off control on the upper slide is only on I think it was post-80's models without the 'pass thru ventilation'. If your wondering what that is, if you have it, you've probably also wondered why there is a torrent of air on the floor when all the vents and everything is off, that is because the pre-80's heat boxes on the inside of the truck firewall have a giant gaping hole in them, they called is 'pass thru-ventilation' and was a feature until too many people bitched about it in the late 70's to remove the 'feature'. pass-thru vent vehicles have no off switch on thier fan or upper slide switch.
The trouble is, the parts books at various parts stores for this part, including AC Delco, is flat out wrong. I know. I researched this very item. If you look in the GM parts books, there are different numbers for the blower wheels. The no-ac, HD heat one is separate, same height as std heat, but slightly larger diameter. The HD heat also takes the same motor as AC equiped trucks, if you look carfully, which, as you mention, also has the little cooling tube to help keep the motor cool. When I ordered various GM part numbers from anyplace I could find the real GM parts, they all came, and you can then see the differences. There are three wheels (actually 6). STD heat, HD heat, and AC with or without HD heat. The reason for 6 is somewhere in the mid-80's GM changed to press-on wheels & motors, as opposed to bolt on. The aftermarket wheels come with an allen set screw which will adapt to both.
BTW, if you order the aftermarket std heat no-ac wheel, it's slightly less tall than the OEM version, as if the blower and wheel already couldn't keep the windshield defogged on a rainy day, do youself a favor, and find a wheel from a junkyard if you need one.
I looked up and ordered (found a dealer out west that had it stock) the metal case that goes on the outside of the firewall for the no-ac HD heat version. The case will accept a larger diamter wheel. Mabey it was only the pre'80's version, there were some differences there as well.
The switch in the dash is also different for HD heat, as you mention. The off control on the upper slide is only on I think it was post-80's models without the 'pass thru ventilation'. If your wondering what that is, if you have it, you've probably also wondered why there is a torrent of air on the floor when all the vents and everything is off, that is because the pre-80's heat boxes on the inside of the truck firewall have a giant gaping hole in them, they called is 'pass thru-ventilation' and was a feature until too many people bitched about it in the late 70's to remove the 'feature'. pass-thru vent vehicles have no off switch on thier fan or upper slide switch.
I was disappointed they didn't use the AC fan on the HD heater option. You'd think it would simplify production to have two fans total.
Is there any likelihood that the fan diameter change(s) were related to years? This has me *almost* curious enough to pull mine apart and check the fan diameter I have.
I'm not sure if I got the fan with the HD setup, or if I just grabbed or had a non-HD fan. I know the AC fan was way too tall, I tried it.
Is there any likelihood that the fan diameter change(s) were related to years? This has me *almost* curious enough to pull mine apart and check the fan diameter I have.
I'm not sure if I got the fan with the HD setup, or if I just grabbed or had a non-HD fan. I know the AC fan was way too tall, I tried it.
It might have been, I don't quite remember. I have GM parts books for 73-78 and also 79-84. IIRC, there were some differences in the 2. I thought I remember that difference being related to the pass-thru ventilation, and resistors, not so much the motor and wheels. I don't quite remember though, and I'm out of town not near my parts books.
You'd be able to tell instantly if your blower wheel just barely barely fits in the hole in the metal case, you have the right one (assuming you have the proper HD heat case on the outside of your firewall). If you pull the motor and wheel, and there's anymore gap than 1/16" all around, then you ahve the std. wheel in the HD case. It's not that much bigger, mabey 1/4" diamter at most, which, yeah, seems silly.
You'd be able to tell instantly if your blower wheel just barely barely fits in the hole in the metal case, you have the right one (assuming you have the proper HD heat case on the outside of your firewall). If you pull the motor and wheel, and there's anymore gap than 1/16" all around, then you ahve the std. wheel in the HD case. It's not that much bigger, mabey 1/4" diamter at most, which, yeah, seems silly.
