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.