With a lull in orders for my driver's door window relay box refurbs and the continued search for a non Chinese located PCB prototype house for my gauge regulator project, I've been using my free time to make progress on some house projects (the work room is the big'n) and investigate some other ideas I've had. One of the big ones that tons of us have had problems with is the shameful inadequacy of aftermarket HVAC blower motors. These aren't nearly as strong as the OEM motors, shriek loudly when in operation (at least to my experience), and are simply not worth the money you spend on them. Granted an OEM replacement is pricey, but my hope is that I can "standardize" a method of restoring these OEM blowers and breathing new life into them for continued use. First order of business is finding out why they go kaput. The most common cause is simply the brushes wearing out. This would typically be an easy fix, but I've come to realize it's damn near impossible to find correctly sized brushes for these, plus the factory brushes are soldered onto the leads from the connector, making them difficult to replace unless you have some experience and knowhow with electronics soldering. Secondary to that is wear on the commutator itself. In most cases this is repairable simply by cleaning up and smoothing out the segments again. I know a few tricks for accomplishing that but also have an old metal lathe I'll be restoring that will really help with that.
The differences between the OEM and aftermarket motors are significant. To start with the housing, which holds the stator magnets, the magnets in the OEM housing are considerably larger. While only slightly thinner than the aftermarket magnets, they measure 39mm long versus the aftermarket 32mm long. Despite being slightly thinner I suspect the much larger face leads to a much stronger magnetic field. Though I can't say for sure I suspect this results in a higher RPM under the same current draw.
On to the rotor assembly, the OEM unit is far more rugged, as can easily be seen just at a glance:
The armature section is not only longer than that of the aftermarket by 11mm (20 for the aftermarket vs. 31 for the OEM), but OEM has 12 segments instead of just 10. So there's far more wire wound around the OEM rotor than the aftermarket. Like with the larger magnets, I believe this translates out to higher RPM (or if not that, more torque throughout the RPM range) while drawing no more current than the aftermarket.
The brushes for the aftermarket motor I lost since taking this one apart, so I can't say what the size comparison is there unless I find them later on.
So I'll be starting with just the basics on this project and hopefully collecting a few more "safe to destroy" blower motors to conduct further experiments with as time allows.
First of all: New brushes. The OEM brushes are 6mm wide x 7mm tall, and (as best I can guesstimate when new) ~12.7mm (0.5") long. The search is still ongoing for a reliable bulk source, but in the meantime I have a pair of brushes I ordered a while back from Roger Brown that pretty closely match the OEM size. They install the same way I intend to have bulk brushes I order install, so these will work for now. They're slightly smaller than OEM size, which means less contact area against the commutator once they're bedded in (3.3mm² less contact area). Exactly how much of a difference this will make in motor performance, I can't say. Unfortunately I struggled with understanding the more advanced information on DC motors and magnetic inductance that was taught when I was taking my course. But to put it in perspective we're talking about an 8% reduction in contact area per brush, so I can't help but feel this does make a difference.
That's all for now. I'll update likely this weekend when I can do a little more research and hopefully some work on a motor.
The differences between the OEM and aftermarket motors are significant. To start with the housing, which holds the stator magnets, the magnets in the OEM housing are considerably larger. While only slightly thinner than the aftermarket magnets, they measure 39mm long versus the aftermarket 32mm long. Despite being slightly thinner I suspect the much larger face leads to a much stronger magnetic field. Though I can't say for sure I suspect this results in a higher RPM under the same current draw.
On to the rotor assembly, the OEM unit is far more rugged, as can easily be seen just at a glance:
The armature section is not only longer than that of the aftermarket by 11mm (20 for the aftermarket vs. 31 for the OEM), but OEM has 12 segments instead of just 10. So there's far more wire wound around the OEM rotor than the aftermarket. Like with the larger magnets, I believe this translates out to higher RPM (or if not that, more torque throughout the RPM range) while drawing no more current than the aftermarket.
The brushes for the aftermarket motor I lost since taking this one apart, so I can't say what the size comparison is there unless I find them later on.
So I'll be starting with just the basics on this project and hopefully collecting a few more "safe to destroy" blower motors to conduct further experiments with as time allows.
First of all: New brushes. The OEM brushes are 6mm wide x 7mm tall, and (as best I can guesstimate when new) ~12.7mm (0.5") long. The search is still ongoing for a reliable bulk source, but in the meantime I have a pair of brushes I ordered a while back from Roger Brown that pretty closely match the OEM size. They install the same way I intend to have bulk brushes I order install, so these will work for now. They're slightly smaller than OEM size, which means less contact area against the commutator once they're bedded in (3.3mm² less contact area). Exactly how much of a difference this will make in motor performance, I can't say. Unfortunately I struggled with understanding the more advanced information on DC motors and magnetic inductance that was taught when I was taking my course. But to put it in perspective we're talking about an 8% reduction in contact area per brush, so I can't help but feel this does make a difference.
That's all for now. I'll update likely this weekend when I can do a little more research and hopefully some work on a motor.
