Presario Fan wont turn on. Any ideas?

Hello,
I have a compaq presario laptop (2100 old) and the fan will not turn on even for a sec. The laptop will overheat and shut off. I have tried the fan on another laptop and it works fine. I also tried two other known good fans on my laptop and it still doesn't work. I tried changing the cpu and still a no go. The pins look fine and I don't see a cold solder problem. I am lost and confussed. Does anyone have an idea? Lastly, there is no fan control in the bios and I updated the bios to the newest version hoping that was the problem... Now, I am at a stand still. I don't know what to check next.

Any help at all would be greatly appreciated!
Thanks,
Jayson

 

The motherboard may be malfunctioning.

 

But what controls the fan on the motherboard?

 

^ Software usually, not the motherboard. I was referring to the connecter on the motherboard may have broken and become loose if you unplugged it many times. This would explain why even fans known to function do not work.

 

Up until it stopped working, I had never unplugged the fan. It looks to be in good shaped. The 3 pins are straight. The connector port does not wiggle at all. Im thinking a temp. sensor or something went out. I just don't know what to look for.

 

It will fail POST if the fans arent connected. (Unless your BIOS is really old and doesnt do a test on the fans). Its supposed to give you a warning saying the fans have failed or arent connected.

Most notebooks dont have fan control. Your ACPI thermal zone sensor might be malfunctioning. This is what triggers the fans to engage.

What cpu?
Are you still able to log into windows? If so, can you download HWMonitor and post up the temps.

 

It has a AMD Athlon™ XP-M 2500+, 1.88 GHz. I am guessing the bios is older and does not test the fan because even uplugged it post just fine and can log into windows. I have the motherboard out on a bench with just the memory, powerboard and cpu installed. It will work fine until it overheats then it shuts off. I aimed my desktop fan on the cpu heatsink and it ran for hours no problem. If I could get the fan to work, it would still be a old but good laptop.

Where about is an ACPI thermal zone sensor usually located? Is there a check I can do with an ohm/volt meter?

 

I want to thank you both for your help. I still havent figured this one out. It is driving me nuts!

 

If I had to guess, the CPU thermal sensor would be near the center of the socket under the CPU. The BIOS normally handles fan control but it can be overridden.

Maybe Speedfan will let you force the fan on? It isn't always compatible but given the vintage of your notebook it should recognize the chipset.