Unwired Tools Recall - PeachParts Mercedes-Benz Forum

wbrian63 · #1 06-10-2008, 09:33 AM

Hope this is the right section to post this informational thread...

I received yesterday by certified US mail, a recall notice from UnwiredTools LLC. They're recalling all UTBR140 and UTBR210 blower regulators.

Here's the text of the letter:

UnwiredTools, LLS announces a potential hazard arising from the possibility of certain conditions occuring when the following products for the Mercedes 140 and 210 Chassis vehicles are used:

Recalled Product: UTBR140 Blower Regulator & UTBR210 Blower Regulator

Hazard: It is possible for the AC blower used in Mercedes 140 and 210 chassis vehicles to greatly increase in current during its service life. If this condition does occur it may be due to brush wear or bushing failure in the motor itself. In fthis condition occurs the running current of the blower may increase 50% to 100%. Some vehicles equipped with these blowers have a improper fuse with a 70a rating. The proper rating for this fuse is 50a. In addition, this fuse is often a slow-blow type which tolerates a substantial over-current without protecting the load circuit above the rating of the fuse. If these conditions occur it is possible for the UTBR140 and UTBR210 products to overheat and fail. The product may stop working altogether, or it may catch fire and cause damage to the vehicle. No injuries have been reported.

Until a suitable replacement blower regulator can be found customers are strongly urged to replace the blower motor fuse with one a 30a rating and to have the blower motor current checked.

UnwiredTools, LLC is recalling all UTBR140 and UTBR210 products to prevent potential damage to the vehicle. For more information about this recall, please contact UnwiredTools, LLC. Contact information is available at the top of this Product Recall Notice.

Contact Information:
UnwiredTools, LLC
2200 East Cedar #1
Flagstaff, AZ 86004
www.unwiredtools.com
info@unwiredtools.com

Ignoring the poorly phrased and technically challenged recall notice, my experience with this product was less than satisfactory. It "cooked" itself within a relatively short time of installation.
That being said, the regulator seemed to be a very satisfactory attempt at a redesign of an expensive MB-specific part. I assumed that UnwiredTools would not have marketed a product that was incapable of regulating a properly-functioning 140 chassis HVAC blower motor.
Getting the specs on current draw for the motor was challenging, but obtaining that info and using an "amp clamp" on the primary lead revealed max current draw about 10-15% above specs.
Replaced the motor, but the cooked regulator was not long for this world. Replaced the UnwiredTools product with the MB part and haven't looked back.

My take on this is that UnwiredTools is making a reasonable attempt to prevent problems with their products when installed in situations that can involve conditions beyond the tolerance capacity of their product. My experience with the regulator indicated that it was experiencing thermal issues (due to excessive current draw) beyond its design capacity. I could smell the "potting" - hope that's the right term - resin getting hot from the airflow in the cabin. Opening up the blower housing revealed a regulator that had definitely been "hot".

In my case, I don't think that the unit would have caught fire, but the amount of amps flowing directly from the battery through this system (I'm not sure if it is even fused - I think the system on the 140 chassis is designed so that the regulator acts as the fuseable link) is not trivial, and a catastrophic failure could result in a fire. In my situation as time wore on, the regulator would simply cut out at high fan speeds.

In any case, any member that has purchased one of these products should use the contact information listed previously to see what UnwiredTools intends to do.

I will make my contact today and will report back my experience.

e300D97 · #2 06-10-2008, 10:13 AM

I called them yesterday asking about the certified letter I received. I am going to call back and find out what they intend to do. I doubt they will refund, hopefully they will replace with a compatible part.

JimF · #3 06-10-2008, 10:58 AM

Quote:

Originally Posted by wbrian63

Hope this is the right section to post this informational thread...

I received yesterday by certified US mail, a recall notice from UnwiredTools LLC. They're recalling all UTBR140 and UTBR210 blower regulators.

My experience with the regulator indicated that it was experiencing thermal issues (due to excessive current draw) beyond its design capacity. I could smell the "potting" - hope that's the right term - resin getting hot from the airflow in the cabin. Opening up the blower housing revealed a regulator that had definitely been "hot".

I agree that the product design was mostly smoke and mirrors b/c power is power. In a conversation w/ a 'technical' person, I never could get an answer to how it could dissipate less power than a 'standard' regulator.

Matt L · #4 06-10-2008, 12:56 PM

Quote:

Originally Posted by JimF

I agree that the product design was mostly smoke and mirrors b/c power is power. In a conversation w/ a 'technical' person, I never could get an answer to how it could dissipate less power than a 'standard' regulator.

I cannot tell you how that particular piece works, but I can tell you how this could be done.

The stock regulator has a power transistor that controls a partial load by imposing a constant restriction to the current. That is, the transistor runs at a partial conductance at all times.

Computer power supplies have a similar circuit to control the voltage to the system, but the industry left partial-saturation devices in the dust bin long ago. Rather, they use what is called a "switching" supply, which runs the transistors with either zero or full conductance. When you quickly switch a MOSFET to control the power (with PWM, for example), the only time the MOSFET actually uses any power is during the switch itself, and that switch is very, very fast.

If you never have partial conductance, you aren't doing any work and you don't have to release heat. Computer power supplies went this way to save power. Of course, since the MOSFETs aren't perfect and do actually have a (small) switching time, there is some heat released. But that heat is minimal compared to a similar circuit using a bipolar transistor in partial-saturation mode.

Bill Wood · #5 06-10-2008, 01:00 PM

FYI
Phil sent a copy to UnwiredTools of all Fastlane orders we have ever filled for their W140 and W210 blower regulators. UnwiredTools is contacting all of the affected customers directly regarding this recall.

JimF · #6 06-10-2008, 01:46 PM

Quote:

Originally Posted by Matt L

The stock regulator has a power transistor that controls a partial load by imposing a constant restriction to the current. That is, the transistor runs at a partial conductance at all times.

Check out this thread Bad blower motor regulator wanted
We disected a MB regulator both mechanically and simulation wise.

Quote:

Originally Posted by Matt L

Computer power supplies have a similar circuit to control the voltage to the system . . . they use what is called a "switching" supply, which runs the transistors with either zero or full conductance. When you quickly switch a MOSFET to control the power (with PWM, for example), the only time the MOSFET actually uses any power is during the switch itself, and that switch is very, very fast.

If you never have partial conductance, you aren't doing any work and you don't have to release heat. Computer power supplies went this way to save power. Of course, since the MOSFETs aren't perfect and do actually have a (small) switching time, there is some heat released. But that heat is minimal compared to a similar circuit using a bipolar transistor in partial-saturation mode.

The difference is that a SPS starts with "AC", not DC. It's a whole different ballgame b/c you need an inverter. They are tough on power, ie not very efficient and so you require more power than would a standard regulator.

Power is power and it has to be the same amount that's delivered to the load. You may save some 'heat' via switching but 'eat' power b/c of the inverter. So heat is generated. Since they are recalling the devices, they are NOT 'heat-less'!

We tried one at my tech's shop and came to the same conclusion; it was replaced w/ the latest version MB regulator.