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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Australia Car
Satisfied Customers: 2514
Experience:  AA in automotive Technology, 15+ years in the trade
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KIA Grand Carnival 2008 VQ Rear blower does work at all.

Customer Question

Hi George
KIA Grand Carnival 2008 VQ
Rear blower does work at all.
Submitted: 11 months ago.
Category: Australia Car
Customer: replied 11 months ago.
Hi
It's likely that I caused this problem some how. I had one of those pesky air-con leaks that no-one could find so I had to search the complete circuit. I found the leak in the condenser and simply replacer the condenser. Put all the covers back etc. only to find that the rear blower is now not working. Front is fine. I tested the voltages at the MOSFET connector and found OV for position 0, and then weird unexpected voltage for the other 4 settings. They weren't consistent and were between 11.2V and 11.5V. The power to the MOSFET was either 13.75V or 14V. Any tips for diagnosing the root cause of this fault?
Customer: replied 11 months ago.
Did a reset of the system by disconnecting ground and leaving disconnected fro 30+ seconds then reconnect. Rear blower still does not work.
Customer: replied 11 months ago.
After a bit of reading on the internet I found that the control voltage to the MOSFET may be a PWM signal and is probably why I am not getting the control voltage difference I was expecting. Is this correct? Since I am getting a voltage does this mean the switch assembly is OK?
Expert:  Pete replied 11 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

What needs to be done as this may have been caused when the repairs were done previously is to check over the work that was done to see if any connections were left loose or damaged in any way needing reconnected or repaired.If a fault is found with any of the connections or wiring this will need repaired.Usually this is the cause here when work has been done previously before this fault occured.If this is all checked and found to be o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 11 months ago.
Hi Pete
I double checked the connections where I was working and they look fine. Can you tell me if the 11.2V to 11.5V is expected for the 4 fan settings. Is it a PWM signal? In the circuit excluding wiring and plugs there are 4 components; the relay, the control panel, the MOSFET and the motor. What I am trying to do is to find a method to diagnose each component so I can find the fault, buy the part and have the system running again. What I am hoping you can provide me with is a method to check each of the 4 parts for correct function.
Kind Regards
Derek
Customer: replied 11 months ago.
BTW I am in Australia.
Expert:  Pete replied 11 months ago.

I apologize for the delay as I was off line the past couple of days.

Unfortunately I dont have the diagram or testing info on the wiring for this here myself.

I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.

Thanks Pete

Expert:  K. Wiggins replied 11 months ago.

Hello, if you unplug the blower motor and measure voltage at the connector it should start off around 3.8 volts on low fan speed and go up slightly with each increase of fan speed up to 11..8 volts on high.

From what you describe the mofset is most likely faulty. On these vehicles I recommend replacing the blower motor and the mofset together as high amperage draw from a worn blower motor will cause the new mofset to fail prematurely.

If my answer has helped you, please help me by leaving a rating using the stars at the top of this page or accept the answer so I may be credited. Rating or accepting my answer does not end our conversation and follow up questions concerning this are free. Thanks!

Customer: replied 11 months ago.
Hi K
I have checked the voltage at the MOSFET connector (i.e. the connector was disconnected from the MOSFET) but not the voltage at the motor connector. I will test the voltage at the motor connector tomorrow. As per my previous post I tested the voltages at the MOSFET connector and found 0V for position 0, and then an unexpected voltage range for the other 4 settings. They weren't consistent and were between 11.2V and 11.5V. The power to the MOSFET was either 13.75V or 14V. Is this voltage of between 11.2V and 11.5V typical as an input voltage to the MOSFET for my model? Is it a PWM signal?If the voltage from the control panel is normal for speeds 1 - 4 (11.2V - 11.5V) and assuming the MOSFET is faulty could I use the MOSFET from the front blower system to test the rear blower? What is the resistance of the motor if it is not faulty?
Expert:  K. Wiggins replied 11 months ago.

I'll post the wiring diagram below from a sedona, which is the us equivalent of the carnaval.

You should be able to swap out the front mofset with rear for testing.

Expert:  K. Wiggins replied 11 months ago.

Sorry let me reupload it, you should see battery voltage on pin 1 and the module should vary voltage to the mofset.