Better ways to control a blower motor?
Ok, electrical gurus, I'm looking for a better way to control a blower motor.
So I bought my GF a 94 jeep cherokee to drive back and forth to work. I noticed the blower motor switch was backwards, high was low, and low was high. So one day while I had the dash apart to swap guage clusters, I pulled the hvac control and found the switch was simply installed upside down. I found the electrical connector looked like it had gotten hot at one time, as it was a little melted, but still looked ok enough to use. I'm thinking someone replaced the switch in the past. It also had a slight electrical gremlen, where every now and then, when you start the jeep, the hvac, radio and a few other things wouldnt work. Turn it off then back on and it would work. I traced the problem down to the ignition switch. I got a new one and found one of the wires on it had gotten hot and kinda burnt one of the contacts inside the switch. I looked at the wiring diagram and found its the wire that powers the blower motor/hvac and a few other things. Google found this was a common issue with these models and many have died a early death from fires. The wiring is just not up to snuff for the blower motor. From what I gather, as the blower motor ages, it pulls more power then everything melts. I have read a few reports that even after replacing the blower motor and fixing the burnt connectors, they still get hot. The factory wiring is just not good enough. There are a couple fixes, some using like 3-4 relays, but I was thinking surely there is a better way.
So I then remembered my 99 grand cherokee. Its a limited model and has the automatic zone control hvac. The blower motor on it is controlled by a module. Two large wires going in it from the battery, then two large out to the blower motor. It then has one smaller wire that controls it from the hvac contoler. The original blower motor module had some issues, I had to replace mine. But the new updated one seems to be working great. So I was thinking something like that would be great, as its infinate/variable speed. Just need a way to control it. I was hoping it was something simple like a 0-5v or 0-12v control from a potentiometer (aka, the speed control knob on the dash), but according to the service manual, its pwm. Could I even be able to control something like that without the factory control module?
But, it doesnt have to be that module. If anyone knows of a vehicle that uses something simillar but is easyer to control I could get from the junkyard, that would be fine too.
My perfect end goal, would be to use the original wiring to trigger a relay to send power on some larger guage wires straight from the battery to the controller/module, then from the controller/module to the blower motor. I would like to get rid of the factory wiring and resistor pack.
So, whats yalls opinions/ideas?
