Fan sometimes only works on High.

[happydog500]

My fan works good most of the time. Sometimes it only works on High.

It still happens after I replaced the Control Unit on the dash and, the Blower Motor.

If it starts acting up, it always works on High, but not the other 3 settings.

Can't tell for sure, but I think it could be coming out very little, like lower then the lowest setting, on the first 3.

Any info of what it could be?

Thank you,
Chris.

[Smith1000]

Sounds like the relay on the firewall, under the hood. I have had one go out on at least one of our Lesabres. I have one going out on a Nissan truck currently. It works on all speeds except high. From what I recall, they run about $20-25 to replace.

[happydog500]

Thank you for replying.

Did any of yours work right sometimes?

My GM Book shows a, "Blower Resistor Assembly", a "Blower Control Module" a "Blower Relay" and a "Blower Speed Relay". Anyway to test a relay? I'm guessing if it's the problem, it would be the, "Blower Speed Relay?"

Chris.

[HotZ28]

Do you have Auto climate control? If so, you have a blower control module and no relays!

[happydog500]

No, I just have the Basic Heater Control.

I have a, "Not this again" Feeling. I replaced a relay on something else and it wasn't it. It does sound like the Relay is it, since that is what controls the speed of the fan?

Chris.

[HotZ28]

The manual system has two relays for the speed control. One for high speed and the other for the lower speeds. The resistors are located in the fan box and the relays on the fuse/relay panel mounted on the firewall. BTW, the resistor controls the fan speed, not the relay!

[Smith1000]

I believe you are on the right track. I recall that when I was trying to figure mine out, I swapped some relays around on the firewall and had all high speeds at one point (it was either off or all high speed). Another time, I had no low speeds and only a high speed when the switch was moved completely to the right.

On my Nissan, I believe my high speed relay is out. I can do without the high speed in the truck.

For the Lesabre, I had a high speed, but needed the lower speeds. That is the relay I ended up purchasing. I had temporarily swapped in the relay from the other Lesabre and it worked.

The salvage yard would be a good place to get a relay. They probably have tons of them.

[happydog500]

Originally Posted by HotZ28

The manual system has two resistors & two relays for the speed control. One set for high speed and the other set for the lower speeds. The resistors are located in the fan box and the relays on the fuse/relay panel mounted on the firewall. BTW, the resistor controls the fan speed, not the relay!

Does this mean it's not the Relay?

[happydog500]

OK, I think I got it now. After talking to my friend (I've told you about him in other posts, hes the mechanic that knows everything about everything), I understand the resistors are for 1,2,3 settings.

When you turn it on full, it gets straight current from the battery, bypassing the resistors.

So, if it works on high, but not the other settings, it's the resistors.

It was getting late, and very cold, so I looked at what I need to do to get to the resistors.

Attached is a photo with questions.



Book says, "4. Underhood fuse blocks and relays form bracket to front of dash, and bracket from vehicle." Does this mean take out the things that hold all the fuses and the square things underneath?

"5. Nuts attaching multi-use relay and fuse bracket to front of dash, and bracket from vehicle." I see the nut on the left, but I can't see a nut on the right. I'm guessing it's underneath the big bundle of wires? I tried grabbing them to move over, but it's like a steal pipe. I can't move them.

Does anyone have better pictures or drawings to better show what to do?

Thank you,

Chris.

[Smith1000]

I believe the relays are right underneath the black (square things underneath), elongated boxes along the firewall. There should be 2 that are for the fan. One will be for the lower speeds and one will be for the high speed. HotZ noted the resistors are in the fan box and the relays are along the firewall.

I recall that it is difficult to tell which relay to pull. They are not marked. They are kind of difficult to pull out. Some of the ones I pulled out in mine are still kind of hanging out by the wires. When I pushed them back in, they did not clip into place.

[happydog500]

Originally Posted by Smith1000

I believe the relays are right underneath the black (square things underneath), elongated boxes along the firewall. There should be 2 that are for the fan. One will be for the lower speeds and one will be for the high speed. HotZ noted the resistors are in the fan box and the relays are along the firewall.

I recall that it is difficult to tell which relay to pull. They are not marked. They are kind of difficult to pull out. Some of the ones I pulled out in mine are still kind of hanging out by the wires. When I pushed them back in, they did not clip into place.

The relays are not the problem. The resistor controls the speeds 1-3. I have to take the white thing off and get to the resistors behind the fuse block.

Chris.

[HotZ28]

[HotZ28]

I have to take the white thing off and get to the resistors behind the fuse block.

Where is this "white thing"? Can you post a pic?

[happydog500]

The resistor is inside the housing the fan motor fits into. It's off to the left of the fan, on top, underneath the max fuse holder. I have to take off the part that holds all the stuff your arrows are pointing at. The whole thing has to come off, according to my GM Service Manual.
In my picture, it's white.

Being specific, if you see on the bottom of my pic (first photo), there is a yellow tag. If you see a bundle of wires next to it, that goes up, under the white holder, to the resistor.

Not sure, but the book sounds like I have to take all the fuses out, and the all the relays, to take off the white thing.

I can't even get the wires out of the way, to get to the nut on the right side of the white part.

autozone, GM Service Manual, Haynes, none show how to get it off, just that it needs to come off.

Here is where I need to get to (part #3 is the Resistor;

[happydog500]

I just noticed my quote in your post. "Behind" the fuse block should of been, "underneath."

Another thing I miss quoted. I couldn't find anything at autozone repair guide for the resistor. Sorry.

Chris.