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George H.
George H., Hyundai Technician
Category: Hyundai
Satisfied Customers: 2033
Experience:  Hyundai Gold certified, ASE Master tech 15+ years
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Hyundai Sonata GLS: A/C stuck on high speed

Customer Question

Good day sir, I have sonata GLS 2006, suddenly A/C stopped working on the low speed at all, and only works on high speed and very rarely on medium speed. I know very well this usually will be caused by the blower transistor (resistor) , so I changed it with new one but unfortunately the same problem is still there, which means this part is healthy and OK !! I want your here to guide me for the next step and the right part to be replaced plz advice For your information, my AC is electronic not the manual one. Thanks

Submitted: 1 year ago.
Category: Hyundai
Expert:  I. Silva replied 1 year ago.

Hello...welcome and thank you for using Justanswer.

Is this a dealer blower motor resistor ?

I believe that you may have a bad/tired blower motor ,it only works when have full battery voltage (high speed)

I would check for power in all speeds at the blower motor ,if there is power and ground ...replace the blower motor.

Let me know .

Thank you.

Expert:  I. Silva replied 1 year ago.

Disconnect the blower motor plug to check for power and ground at all speeds and also make sure the plug is not burned out.

Let me know.

Customer: replied 1 year ago.

The one I have is a transistor not a resistor, the attached pic is an exact sample of it ( https://www.dropbox.com/s/9rohh66r9fcom3z/TR.jpg?dl=0 )

I will go with your suggestion checking the blower motor (what is the testing method you want me to do confirming the status of the blower?)

Note:
Thanks for your help, but I think the blower is ok!
From my technical experience, since the blower is two wire, so it only gives the high speed when connecting to any power and the Transistor is the one how is responsible for controlling the speed, so there is nothing to do with the quality of the blower motor. If it was not ok, it will not work at all.

what do you think I have to go on for further checking besides the blower motor ?

Expert:  I. Silva replied 1 year ago.

Yes ,it is a two wires like most of the blowers out there.

Using a voltmeter on the two wires ,check for voltage increase when increasing the blower speed.

with transistor you should get an average voltage increasing with blower speed.

Check the fuses.

Let me know.

thank you...sorry for the wait.

Customer: replied 1 year ago.

As per your instructions I have disconnected the blower for testing.

My blower had been connected to a car similar to my car and the surprise, my blower had worked very well which means it is very healthy!

And to make sure it is not just happened with luck, I have connected the other car blower into my car, but the same problem is showing up (works only on high speed) !.

That proofs the story of the good condition of the existing blower.

Please advice,

Thanks

Expert:  I. Silva replied 1 year ago.

Hi there ....have you check for voltage increase when increasing the speed of the blower ,like i mention above ?

Have you check all the fuses?

On passenger side fuse box ,there is the blower relay (right side on the box when looking at it ) swap it with another one .

Let me know what you find.

Thank you.

Customer: replied 1 year ago.

Hi

yes, I have checked for the voltage increasing and decreasing with the increasing and decreasing the blower speed and it is fine.

The below link attached the box, could you please help me deciding which one to be swapped ?

https://dl.pushbulletusercontent.com/cGY7bpxNmugf55wYsoWhj0Ga5w7sflVA/IMG-20150508-WA0014.jpg

Thanks for fast repsonse

Customer: replied 1 year ago.

I have just swapped the Blower Relay 40mA (which is up to fuse #14) but nothing have gone clear

Expert:  I. Silva replied 1 year ago.

This is not the diagram i have ...is this the passenger side fuse/relay box(not driver side) ?

It should say on the cover (blower relay)

Let me know.

Customer: replied 1 year ago.

No, this is not the driver side.

I have just checked the passenger side, no fuse box there.

Expert:  I. Silva replied 1 year ago.

I am sorry...on driver side ...behind left side of the dash (inside the vehicle) there is a relay box ,where you should have the blower relay.

Let me know.

Thank you.

Customer: replied 1 year ago.

there are only fuses, no relays there

Expert:  I. Silva replied 1 year ago.

Ok ,we may have a different model ...the info i have is from USA model ,don't know if is the same as yours.

Do you have a yellow and a pink wire going to the blower?

Do you have 3 wires to the transistor ,Blue,Pink and Black ?

The blower relay should be above the fuses.

Let me know.

Thank you

http://www2.prodemand.com/img/G00422268

Customer: replied 1 year ago.

Sorry for being late, I was out of country for 3 day.

Yes, I have a yellow and a pink wire going to the blower, and 3 wires to the transistor ,Blue,Pink and Black.

Here are the only two boxes I have in the car

https://db.tt/9nx5T70E
https://db.tt/mleJAJV0

Customer: replied 1 year ago.

waiting for your help sir :)

Expert:  I. Silva replied 1 year ago.

Hi there....

I need you to check some wires..

Do you have good ground on the black wire to the transistor ?

Do you have power at the yellow wire going to the blower motor ?

I need you to get me the readings at the blue and pink wires ,with key

OFF and also with key ON and blower ON.

The pink and blue wires set the blower motor speed when pulsing ground to it.

Let me know.

Thank you.