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Blower motor issues

650 Views 7 Replies 2 Participants Last post by  metalmike187
I have a 2008 Impala LT
Let me just say.... This car has been a nightmare with constant electrical issues, HVAC issues and constant battery drains. I'm on my 3rd battery in under 5 years. It's frustrating.
But I digress, my question for the moment is why my blower motor isn't working and why does the system attempt to switch from defrost to vent with the car turned off....

A couple years ago I had to change the actuators and ever since my fan hasnt wanted to work as it should. It would periodically come on when it decided it wanted to but it would never remain on. Within a few seconds it would shut back off. It didn't matter if it were the heat or the ac setting, it still malfunctioned all the same. This is the 3rd winter now I've had no heat and because of temps, I would REALLY like to not have windows fog over and to actually be warm during the last few months of winter we have left. I've not been able to do the things I need to do because of this issue. I've taken the resistor out and checked it over, it doesn't appear to be faulty... There doesn't appear to be anything faulty with the blower itself either. And I can't seem to find any relay for the blower motor either. There is nothing in the owners manual, that I can find anyway, and nothing I find online answers the specific question of where the blower motor relay is. Any suggestions on potential causes of blower motor not working (on any speed or setting for the ac or the heat) as well as, is there a relay and where the heck is it located?

I'd also like to know why it tries to switch from defrost to vent with car not even running and key not in accessory position. All I know is I can hear a motor of some sort humming in the dash and the sound of a flap closing, as if it switched from defrost to vent.... I'm wondering if that is the cause of the constant battery drain as well??

Apologies, I know my post is all over the place and unorganized... Hopefully someone is able to decipher my ramblings and help me figure this mess out 馃榿 I'm not a new to cars but I'm by no means a mechanic so forgive my lack of knowledge of proper lingo.
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Do you have single or dual zone climate control?
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Do you have single or dual zone climate control?
Dual
Let's start with the blower motor resistor. Good place to start as they can get corroded and cause all sorts of HVAC issues. I pasted a video below that should help you get started.

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Let's start with the blower motor resistor. Good place to start as they can get corroded and cause all sorts of HVAC issues. I pasted a video below that should help you get started.

I actually have them both taken out already (and I watched this exact video too! 馃榿) But, is there a way I can test them to see if they're shot before buying replacements? I'd hate to spend the money if it's not necessary. I've sunk a lot of money into this car and I'm at that point of questioning if it's even worth it. I do need to make it hold up, though, until I am able to purchase something different and I am too fond of warmth to accept not being warm 鈽

Thank you for taking the time to help, I do appreciate it
The first thing (which I assume you did already) is to inspect the resistor visually. Look for obvious signs of corrosion and burns from overheating. If you see signs of overheated connectors, replace the blower resistor and its connector. If you want to do a quick test of the blower resistor, you can check the resistance of each of the resistors with a multimeter as follows: set the tool to read ohms (a measurement of resistance) and connect one of its probes to the common output terminal of the resistor. Use the other probe to measure the resistance between the output terminal and each of the resistor鈥檚 input terminals. Measure the resistance between one pair of terminals at a time.

Of course, to do this, you need to know which terminal is the common terminal (it鈥檚 the one directly feeding the fan motor). And you鈥檒l also need to know which of the other terminals is which speed 鈥 you can find this information in an online wiring schematic for your vehicle if you know where to look. AutoZone has some great wiring diagrams, and if you can't find them I have the Haynes manual at home with the diagrams. I can snap a photo and share it if needed.
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I will get pictures of the resistor and fan when I get the chance, to show just so you see what I'm seeing. However, I didn't see any charring on the wiring harnesses (if that's what they're called...The wires that connect to the resistor and fan etc) they actual looked pretty darn good in my opinion. The resistor has only what I can describe as, a white film on the metal plates? It looks as if it's just from exposure to the elements of what it's purpose is for and maybe the humidity...and I could be completely incorrect too lol but I don't know what they're supposed to look like so have nothing to compare it to...but that was the only thing I had concern about. Other than that, the fan didn't have charring on the wire harness either. Now, I know and understand that just because it doesn't appear to have anything wrong, doesn't mean there isn't. So that's why I was curious about testing them, which I do happen to have a multimeter. My only other question would be if I have engine running while I do this test or am I able to test without a power source?
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Pictures of what that white film is would be helpful. Is it on the contacts themselves or the metal fins (which are called heat sinks). On the contacts, it might be dielectric grease or something similar. On the cooling fins, I'm not sure what that would be and it more than likely shouldn't be there.

I forgot to ask about coolant levels. How are they? If they are low or the thermostat isn't opening, or if you had work done on the cooling system and haven't bled the air out you may have a pocket keeping the hot water from going into the heater core itself.

It also sounds like it could be a bad door actuator, as they are moving funny. Do you get any clicking noises? These actuators are made from cheap plastic and have a tendency to break at the worst possible times.
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