Electrical Engineer, Licensed CxA, Licensed Electrician. Over 30 years experience in the controls industry designing HVAC, Fire and Security control systems.
Paul, the brass connectors have little tabs on them that hold them in place in the plastic housing. You may need to use needle nosed pliers to squeeze these tabs in while pushing the connectors out of the plastic housing. It may take a bit of force to push the connectors out of the housing but go slow and work them out a bit at a time to prevent breaking anything.
Eric, please read the above response to Trevor. I explained all of this in the original document and again in the response to Trevor. To destroy this during soldering you must have been using way too much heat or you were heating it far too long. Electrically you don't need it but it does make wiring easier if it remains intact. I guess you could solder the wires to the gold PTC tabs and then epoxy the PTC back together. This will restore the ability to use the motor and the wiring harness plugs after you complete the modification. Just make certain that the two gold PTC tabs are not shorted after they are glued.
Eric, please read the above response to Trevor. I explained all of this in the original document and again in the response to Trevor. To destroy this during soldering you must have been using way too much heat or you were heating it far too long. Electrically you don't need it but it does make wiring easier if it remains intact. I guess you could solder the wires to the gold PTC tabs and then epoxy the PTC back together. This will restore the ability to use the motor and the wiring harness plugs after you complete the modification.
Trevor, once again again, a resistor from Radio Shack or anywhere else will not behave like a PTC! A resistor maintains a FIXED resistance. A PTC, like a lamp, varies resistance with temperature! As the motor load increases toward a stall, the lamp brightness increases, resistance increases and this limits the current to prevent possible motor burnout or fire. The PTC in these actuators fails by increasing resistance to the point the actuator motor will not run under load. I did parallel the PTC and that does effectively bypass it because the PTC resistance increased to the point that it would not run the actuator. I paralleled the PTC because it provided the necessary electrical connections to the motor and the wiring harness. It will pass some current but for all practical purposes it only serves as a mechanical termination point for the lamp. The PDF document I wrote explains most of this in detail.
If you used a fixed resistance that was low enough to start the motor and provide enough torque, it would be so low it may not protect the motor in a stalled condition. That is the reason for a PTC or a lamp. LOW resistance cold, HIGH resistance hot. Lamps and heater coils have been used for current limiting for many years. Their use goes all the way back to vacuum tube equipment. (They called them ballast resistors.)
Due to the motor resistance, the lamp never gets bright/hot enough to ever cause a fire from the heat shrink tubing even if the motor was stalled until you ran the car battery down! Heat shrink takes a very high temperature to actually burn and is very flame resistant. (Check the UL listings for that material, that is why I used it.)
Trevor; The root cause of the failure IS the PTC. Dirty, sticking seals etc may help accelerate the process but ultimately the PTC is not up to the task over the long haul. As an electrical engineer for over 40 years I am very familiar with the failure modes of PTC's. One of the problems with these devices is their notorious instability with repeated heating cycles, especially when they get really warm as they will in this application. They have a tendency to increase their resistance. I explained this in the pdf document. You also talk about using a resistor. There is a reason I and the manufacturer did not do this (I also explained that in the pdf). A PTC resistor (a lamp or an actual PTC resistor) exhibits a low resistance when cold and a high resistance when hot. The low cold resistance allows for a high inrush current to start the motor and the high resistance prevents a motor burnout if the motor is stalled.
Did you read the pdf document in its entirety? The purpose of the PTC Thermistor and what can happen without it is explained in the very first paragraph. The lamps replace the function of the thermistor. Do not attempt to use the actuators without this current limiting protection unless you want to risk a vehicle fire!
The lamp will only light very dimly during normal operation. If you stall out the actuator the lamp will light brighter. If you are watching the lamp at the instant power is applied it may also light brighter and then dim down as the motor comes up to speed. The easiest way to test these actuators out of the vehicle is by using a 12V gel cell battery and a pair of Radio Shack clip leads. You simply reverse polarity of the clip leads to change the direction the actuator runs.
The actuators are behind the plastic side panels located underneath the windows. These side panels are held in place with snaps, clips and screws. Take your time and go slow until you find all the clips and screws. If you get in a hurry or force parts they may break. Replacement clips and snaps are dealer only parts and are thus expensive to replace.
1 / 2 页