2005 T4R need your help - Question about cabin air system

[Marde]

Thank you in advance for any help or advice.

Cabin air fan stopped working yesterday. Does not matter if air conditioner (ac) is on or off. Fan is not working in any of the 4 speeds.

I disconnected the fan motor connector and placed a meter (DVM) on the 2 pins of the motor connector and got VERY STRANGE results. Based on these DVM tests, it seems like the fan motor is dead, but the DVM test results are confusing me. Please help! Do I have a dead fan motor and a dead controller? Is there a fan motor resistor that might cause this symptom and with these test results?

This test was done while the engine was running....

Fan switch position/mode:
Off = 0 volts
Low = 12.4V
Low medium = 12.3V
Low High = 12.1V
High = 13.6V

I reconnected the fan motor and still no fan movement at any speed and/or at any mode. The fan motor must be dead... but why are my test voltages so weird & so strange? Do these test voltages seem like a separate problem beyond just a failed fan motor?

Help! -and thank you for any ideas, any suggestions.

BTW the T4R is my ex-wife car and I be trying to help her.

 

[techno]

I recommend going to this link and scrolling about half way down to the Air Conditioning System sections and following some of the diagnosis and inspection procedures. The best way to check the blower motor is by directly connecting battery power to the motor terminals. From a quick look, it seems the blower speed is controlled by the ac amplifier and by varying the duty ratio?
Toyota Factory Service and Repair Manual - 2007 4Runner + Updates

 

[Marde]

...The best way to check the blower motor is by directly connecting battery power to the motor terminals...

Thank you Techno.

I did not directly connect battery voltage to the blower (like on a test bench) but I did the same-similar thing using the car harness connector that is normally connected to the blower. The blower is definitely being fed 12 to 13 volts and is not moving, is not running at all... or do I say is not 4running at all?

I did not know Toyota uses a PWM duty cycle signal to operate the blower. I have a good Fluke (DVM) meter, but it is not a scope meter. So I am unable to monitor the actual PWM signal, but fortunately that is not required.

My tests show the basic stuff is working (fuse & relay) but the values of voltage across the multiple fan speeds are still concerning or confusing me.

I am going to search for and buy a new blower motor today. Either online or at local store.

That link you proved is totally amazing! The amount of info there is mind blowing. Thank you so much.

Cheers!

 

[Marde]

...but the values of voltage across the multiple fan speeds are still concerning or confusing me...

On second thought, the voltage values are no longer concerning/confusing me. If I had used a scope meter I would have seen the proper on-off times of the PWM signal. My DVM test results were confusing me because I did not know I was testing a PWM signal. It finally sunk in.

New blower and cabin air filter arrives on Monday.

Thanks again Techno.

 

[Kevin G.]

Next time it doesn't work.......remove cabin air filter, and carefully flick the fan blades with a fingertip while the a/c is "on".

If it then blows......the fan motor is intermittenly bad.

Hope this helps.

Kevin

 

[Marde]

Great idea Kevin!

That had previously crossed my mind. My house ac unit has had that symptom & solution in the past few years. Outdoor (condenser) fan motor stuck and I kick-started that darn thing using a wooden spoon handle to flick-kick the fan blades to get it going. Then fixed it with a new start/run capacitor. Then same exact thing happened on the indoor unit (evaporator) fan motor, first used the spoon handle, then another new start/run capacitor for that one too.

Start/run capacitor at local ac wholesale place = $10. Flick the fan blades with wooden spoon handle = priceless.

Dang, this forum does not have emoji [thumb] or [cheers] ?

Cheers!