Installed new blower motor resistor, and new blower mower. A month later the blower motor quiet working again, is there anything else I'm missing?
Did you use OEM parts or aftermarket? Check relays and fuses?
OEM for the resistor, after market for the fan, checked the fuses, I'm starting to think now it might be relay, could the climate control also be an issue?
Yes, it's all computer controlled so that has to be taken into consideration. You'd probably need a high-end bidirectional scan tool to test the HVAC system though.
I would test the fan motor by hooking it up directly to 12 volts and measure how much current it is drawing, compare that with the specification.
Even an 08? The scanner isn't very possible for me right now, by the sounds of it I'm gonna have to take to the shop?
Yes, even in an '08 the HVAC is computer-controlled. The HVAC in my 1997 model is computer-controlled. If you cannot find a simple electrical problem a dealer-level scan tool is a requirement for diagnosis.
That's actually a blower motor speed controller.
Here's a simple diagram explaining how it works:
The HVAC Control Head sends a pulse width modulated voltage signal to the Blower (Fan) Motor (Speed) Controller. The Pulse Width of the square wave depends on what blower speed you have selected.
For example, if you selected Low Speed the Pulse Width duty cycle might be around 10%.
If you selected High Speed the Pulse Width duty cycle might be around 90%.
Using that voltage signal the Blower Motor Controller then provides the appropriate Pulse Width GROUND signal to the Blower Motor to control the speed.
Again, if the Ground is being pulsed at a 10% duty cycle the blower will run slow (low speed).
If the Ground is being pulsed at a 90% duty cycle the blower will run fast (high speed).
The Blower Motor always gets Power when the Heat or AC is turned on.
The Blower Motor Controller always gets Power when the Heat or AC is turned on.
I circled the components in Purple that need to be checked.
The IG1 (15 amp) fuse provides Power to the Control Side of the Heater Relay.
The Heater (60 amp) fuse provides Power to the Load Side of the Heater Relay.
When the relay is energized Power goes to the Blower Motor AND to the Heater No.2 (7.5 amp) fuse to power the Blower Motor Controller.
Also on the Blower Motor Controller connector pin 2 (SI) is the Pulse Width Modulated voltage signal input from the HVAC Control Head module. Pin 4 (VM) is the Pulse Width Modulated Ground to the Blower Motor that controls the Motor speed.
Anyway, grab a test light and clip the alligator clip to a good Ground.
Disconnect the Blower Motor connector. Turn on the heater and blower speed to high (to energize the Heater Relay). Probe the connector terminal that has the Black and Yellow wire. The test light should light up.
Next unplug the Blower Motor Controller connector.
Probe the terminal that has the Green and Yellow wire. The test light should light up.
If both tests passed then those 3 fuses and the Heater relay are good.
Next, switch the test light alligator clip to Power and probe the terminal that has the White and Black wire. The test light should light up if there's a Ground present.
If all that checks out then the next steps would be to observe the pulse width modulated voltage signal from the HVAC Control Head module at (pin 2) ((SI)) of the Blower Motor Controller connector and the pulse width modulated Ground signal (pin 4) ((VM)) of the Blower Motor Controller connector to see if one of those is missing.
Nice work Jack. I sometimes forget that people don't know which parts they're replacing, or use the wrong terminology.
I would double check the fan and make sure it is okay. I don't blame you for going after market on it, but that means taking a little risk that it fails early.
So the fan tested good, everything else is good, but something keeps burning up this blower motor resistor. What am I missing that I can't see right now?
after market for the fan
Some of those are junk. I once got one that lasted a year.
So the fan tested good, everything else is good, but something keeps burning up this blower motor resistor. What am I missing that I can't see right now?
How much current is the motor drawing? Excessive current draw is what usually burns out those resistors.
how exactly did it "test good"?
They may appear to work, or work intermittently, when in fact the bearings are dried out and it's starting to seize or the commutators are shorting out. The only thing that can fry resistors is too much current like Chuck said. So either the motor is bad or you have a short in your wiring.