Blower Speeds Problem

aweber · Dec 22, 2007

Hey

I recently purchased an 97 Yukon SLT. When I first got it, Only high speed on the fan setting would work reliably, and the rest of the fan speed would work intermittently.

Next, I lost high as well. From reading on the boards, I thought to replace the blower resister, which I did at expense of some skin on my hands LOL. It is tight in there!!

Well, no luck, still no normal fan speeds, and high is intermittent. If I turn it on high, sometimes it works right away, other times it does nothing for a while, then you hear the relay click and it works...

I can also run a wire directly to the blower motor and that works no problem

So what is my next step? I am thinking the Fan Switch...

Thanks in advance...

Adrian

RonH · Dec 22, 2007

Fan switch, or perhaps a bad ground on the circuit

Hardwarz · Dec 24, 2007

I had the same exact problem. It look like the main problem might be that the blower it's self might be the culprit.

I replaced the resistor pack that's behind the switch. That didn't fix it. Apparently, when the fan starts going bad, it causes the fan to start drawing more current. When it draws more current, the wires get hot and you can get a short.

Hopefully, yours did not melt the insulation. Replace the fan motor. If it did melt the insulation, you have a lot more work ahead of you.

Hardwarz

brodg · Dec 24, 2007

you have a faulty high blower relay it is next to the resistor all speeds go through it.

41racing · Dec 24, 2007

I've replaced lots of blower switches and connectors for this problem. What happens is the blower motor gets wore and draws more amperage, which in turn melts the connector into the switch. To fix it right you'll have to replace the blower motor also, and if it was mine I'd put in the resistor too.

aweber · Jan 14, 2008

OK, I just got around to looking at this again, Been pretty busy...

I took apart the dash and found a nice surprise. Looks to me like the blower motor went at one point and burned the wires and connector at the switch. They just duct taped the switch and connector together and put it back in LOL

I measured the Blower on High and it is drawing 14 Amps. This does not seem to high to me, so I am assuming it was replaced.

I managed to separate the switch from the connector and clean up the connector to the point that I think it will work fine, I will buy a new switch tommorrow..

Am I correct about the Blower Amperage?

Thanks!

Adrian

41racing · Jan 14, 2008

I'm thinking that it should draw somewhere around 8 to 10 amps. I'm not sure though, but 14 seems a little high. I'll check mine tonight if it's not -20* when I get home.

Mike97 · Jan 14, 2008

I agree with 41. I would think that it should draw less than 10 amps, but I really don't know what they are rated at.

41racing · Jan 15, 2008

Way too cold to check it last night, and it's suppose to be very cold for the next week or so (-15* and colder). If I drive it to work one day I get it in the shop and check it.

Black96 · Jan 15, 2008

41racing said:
I've replaced lots of blower switches and connectors for this problem. What happens is the blower motor gets wore and draws more amperage, which in turn melts the connector into the switch. To fix it right you'll have to replace the blower motor also, and if it was mine I'd put in the resistor too.

i have had the same problem, i took apart the switch connector and it was all melted, i would look into that first cause its something easy to get too

Hardwarz · Jan 15, 2008

Black96 said:
i have had the same problem, i took apart the switch connector and it was all melted, i would look into that first cause its something easy to get too

I thought mine was the switch too, problem is that if the root cause is the fan, you'll keep burning out switches and probably have a fire on your hands.

On a side note, should we put in 10 or 15 amp inline fuse on these to protect it from it's self?

Hardwarz

Mike97 · Jan 15, 2008

Hardwarz said:
I thought mine was the switch too, problem is that if the root cause is the fan, you'll keep burning out switches and probably have a fire on your hands.

On a side note, should we put in 10 or 15 amp inline fuse on these to protect it from it's self?

Hardwarz

The fuse probably would not blow. I'm sure that this circuit is already fused. If you install a fuse that is too close to the rating of the motor, the fuse will blow when the fan is turned on. This is because start-up current on an electric motor is much higher than steady state current.

The reason the connectors melt is because over time, a connector can lose the ability to conduct because of oxidation, and will start to build up resistance. The blower motor requires a certain amount of current to do it's job, and will be trying to draw that amount. The connector starts to heat up because of the resistance that is forming within, limiting the current. Over time, this heat starts to damage the connector and associated wiring, making the problem worse.

The best way to prevent this is to disconnect the blower motor and clean the contacts on the connector. Then apply conductive grease to the contacts. This should prevent the connectors from heating up.

Hardwarz · Mar 3, 2008

did you ever get this fixed? I've replace my motor, switch resistor pack and I just purchased the replacement plug for the heater switch from the dealer. I'm going to look at the resistor next.

Hardwarz

aweber · Mar 3, 2008

I took apart the switch and the inside was all burned and corroded.

I replaced it and it has been fine since.

I was able to get one at NAPA pretty cheap...

madspeed · Mar 3, 2008

aweber said:
I took apart the switch and the inside was all burned and corroded.

I replaced it and it has been fine since.

I was able to get one at NAPA pretty cheap...

happen to have a part ##??

aweber · Mar 3, 2008

madspeed said:
happen to have a part ##??

Not anymore, he cross referenced it using the OEM GM part #...

madspeed · Mar 3, 2008

Echlin HC110 perhaps?

madspeed · Mar 3, 2008

aweber said:
I took apart the switch and the inside was all burned and corroded.

I replaced it and it has been fine since.

I was able to get one at NAPA pretty cheap...

Oh, and by the way, same thing with mine. the copper contacts were just plain worn down, similiar to a distributor cap guts

aweber · Mar 17, 2008

madspeed said:
Echlin HC110 perhaps?

Just found the old box and yes, you are right on the money

Blower Speeds Problem

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