HVAC blower motor

[TIM Z]

HVAC blower does not work on high, every other speed is good,

Im thinking its a relay under the glove compartment?

 

[Flyhatch]

I have the same issue with my 95. I replaced the resistor in the glove box, but I still dont have high.

 

[TIM Z]

I have the same issue with my 95. I replaced the resistor in the glove box, but I still dont have high.

Hmm, what could it be then

NAPA tells me there is a resistor and a high speed blower relay, I havent tore the glove box out yet, but not sure what to replace now.

My Dads 96 Suburban only blows on high,

 

[TIM Z]

Ok, checked the relay , its fine,

Replaced the resistor, Still no HIGH ?

Even tried a new HVAC control panel i have, still no worky on high.

The only thing to replace is the blower motor ????

 

[TIM Z]

Still dont have high ?

Has any one had this problem before ?

Any help appreciated!!

 

[TIM Z]

Well my fathers second suburban ( a 99') just quit working on high also.

We are stumped! Someone has had to fixed this problem before!

Thanks in advance for any help!

 

[JKmotorsports]

The resistors have nothing to do with the high speed setting, only the slower speeds. The resistors provide resistance in the circuit, dropping voltage to the blower motor to slow the motor speed down. On high, the blower receives full voltage through the blower relay. If you had High but no other speeds, then the resistor pack is usually the culprit.
If you have all other speeds but high, the most common problem is going to be the blower motor itself, relay, or the switch panel. You can check this by turning the fan speed to "high", unplug the blower motor, and check to see that you have roughly at least 12v at the plug. If you have 12v, that means the switch panel is activating the relay and the relay is working. Over time, heat kills the magnetic properties of the magnets inside an electrical motor. Without enough magnetic energy, you may not get enough opposing force to spin the rotor full speed when the windings energize, but still enough to spin at lower speeds.
Another thing you can check is the connector at the blower motor and the switch panel. Sometimes these will heat up, start to deform, and cause a bad connection. The bad connection may be able to handle the lower current draw on low speeds, but the higher resistance from the bad connection won't be able to handle the higher current while in the full speed position.

 

[TIM Z]

The resistors have nothing to do with the high speed setting, only the slower speeds. The resistors provide resistance in the circuit, dropping voltage to the blower motor to slow the motor speed down. On high, the blower receives full voltage through the blower relay. If you had High but no other speeds, then the resistor pack is usually the culprit.
If you have all other speeds but high, the most common problem is going to be the blower motor itself, relay, or the switch panel. You can check this by turning the fan speed to "high", unplug the blower motor, and check to see that you have roughly at least 12v at the plug. If you have 12v, that means the switch panel is activating the relay and the relay is working. Over time, heat kills the magnetic properties of the magnets inside an electrical motor. Without enough magnetic energy, you may not get enough opposing force to spin the rotor full speed when the windings energize, but still enough to spin at lower speeds.
Another thing you can check is the connector at the blower motor and the switch panel. Sometimes these will heat up, start to deform, and cause a bad connection. The bad connection may be able to handle the lower current draw on low speeds, but the higher resistance from the bad connection won't be able to handle the higher current while in the full speed position.

Awesome! Thankyou for the time/Reply!

My next step was to replace the blower motor but was told if it works on low it should work on high,

I like your explanation on how the blower motor declines over time, wasnt aware of that.

Now im going to get a replacement blower, eveything else has been done.

Thanks again man!

 

[JKmotorsports]

No prob, man. I would check that you are in fact getting at least 12v at the blower plug though while in the high spd position.

 

[TIM Z]

No prob, man. I would check that you are in fact getting at least 12v at the blower plug though while in the high spd position.

That is one badass Tahoe!

Are you a member on performance trucks.net? Lots of guys with magnachargers there.

My old truck was an 04 Z71 with a. STS turbo intercooled kit/ comp cam / Precision ind stall/ built trans.

Man boost is the best!!

My next build i want to do a maggie on an LS1 or twins.

 

[JKmotorsports]

Thanks bro
Yea, I'm over at pt.net also under the same user name.
I thought about going with the STS kit also, but decided on the maggie for the flatter tq curve.

 

[TIM Z]

Thanks bro
Yea, I'm over at pt.net also under the same user name.
I thought about going with the STS kit also, but decided on the maggie for the flatter tq curve.

Good choice, i think a bigger vehicle likes the maggie better, they seem to get everything moving .

Im still a member but last time i was there there were guys running maggies running low 12's, KYsilverado ( roger) and Trevor i believe.

I need to get back and do some reasearch LOL!

 

[atjones44]

To bring this back from the dead....Im working on a buddys '99 caddy escalade.
his blower motor doesnt work at all. ac or heat. the rear ac works ok though.
To provide as much info as i can...I can turn the switch to high and feel the relay click in the glovebox. the blower motor never moves...Is this the motor that needs replacing or could it be the blower resistor.

Thanks, and this is my first post on this forum

 

[TIM Z]

To bring this back from the dead....Im working on a buddys '99 caddy escalade.
his blower motor doesnt work at all. ac or heat. the rear ac works ok though.
To provide as much info as i can...I can turn the switch to high and feel the relay click in the glovebox. the blower motor never moves...Is this the motor that needs replacing or could it be the blower resistor.

Thanks, and this is my first post on this forum

Welcome and glad ya brought it back from the dead!

I havent checked mine yet as i just got it back from the body shop ( had some paint work done.)

Any way did you check the plug on the blower motor to see if you have power there first?

If you have power i bet your motor needs replaced.

Let us know, Good luck.

 

[TIM Z]

Well, i still had no luck in getting the blower to work on high.

So i took apart the dash again, wiggled the wires around the fan speed switch, and no High works!

Dont know why, but thank god i ve better heat now!

Just thought i'd post to maybe help someone else!

 

[pmdogg]

i have the same problem with my yukon xl 2000
i just want to know if you have changed the blower

because i have 12v on the plug but the speed 5 still no works
it is the blower i need to change
thx

 

[TIM Z]

i have the same problem with my yukon xl 2000
i just want to know if you have changed the blower

because i have 12v on the plug but the speed 5 still no works
it is the blower i need to change
thx

No its the relay under the pass side of the dash, ive put 2 of them in my wifes Tahoe.

 

[pmdogg]

do you have shema or picture of the location of this relay
because me i got 12v on the plug going to the resistor but from the resistor to the blower motor 0v when i put on setting 5 i realy dont know whats the problem with the high speed setting

 

[pmdogg]

resolved just a 25amp fuse in the hood fuse box now the horn lol

 

[goose40]

Thank you, that clears it up for me as well...

The resistors have nothing to do with the high speed setting, only the slower speeds. The resistors provide resistance in the circuit, dropping voltage to the blower motor to slow the motor speed down. On high, the blower receives full voltage through the blower relay. If you had High but no other speeds, then the resistor pack is usually the culprit.
If you have all other speeds but high, the most common problem is going to be the blower motor itself, relay, or the switch panel. You can check this by turning the fan speed to "high", unplug the blower motor, and check to see that you have roughly at least 12v at the plug. If you have 12v, that means the switch panel is activating the relay and the relay is working. Over time, heat kills the magnetic properties of the magnets inside an electrical motor. Without enough magnetic energy, you may not get enough opposing force to spin the rotor full speed when the windings energize, but still enough to spin at lower speeds.
Another thing you can check is the connector at the blower motor and the switch panel. Sometimes these will heat up, start to deform, and cause a bad connection. The bad connection may be able to handle the lower current draw on low speeds, but the higher resistance from the bad connection won't be able to handle the higher current while in the full speed position.

Excellent post! Thanks for helping me with my troubleshooting. Long story short, '99 OBS 2-dr, fan blows on all speeds weakly, gets better if I "fix" it with a rap to the blower cover (not hard, I just have to tap it a little). Seems like resistor is working since fan changes speeds with switch position (incl max). I suspect the blower motor is going bad (it's the original).

BTW it's a real ******** to get at the resistor in a '99 even after popping off the glove box door because all of the passenger side airbag crap leaves about 2.5 inches of clearance between the top of the heater airbox and the underside of what's above it. It looks like I will have to remove the dash to be able to get the motor out when it finally quits.

Thanks forum folks, I'm always getting great info here!! (Like the day I learned how to turn off my DRL's...)

Steve