HP Pavilion ze5155. Anyone own one? Fan question

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I just received my father-in-laws old laptop, HP Pavilion ze5155 that
has two fans.  When I first turn the unit on, i.e. cold, only one fan
spins, the one furthest from the rear connectors on the back of the
laptop.  Even when hot, I never see this fan spinning.   In addition
with the power off if I reach through the grill and try to spin the
fans manually with a small probe, the one that works spins easily and
spins for about 2 seconds before stopping.  The fan I never see
spinning, doesn't spin at all, it just wobbles a bit.  Can anyone who
owns this model check their fans and let me know how they are supposed
to work, cold and hot?

Also, anyone ever open the case on this laptop?  If it's easy enough
I'll try taking them out and debugging them, or simply changing the

Thanks in advance,
John G.
Barrington, RI

Re: HP Pavilion ze5155. Anyone own one? Fan question

JohnG here again.  Turns out there are three fans, the two on the CPU
heatsink assembly and a separate "case" fan.  Only one fan works on
mine.  There is a fan test in the HP ediagnostic program that is
accessible from boot by hitting F10.  When I run that test, my good
heatsink fan spins, the second heatsink fan tries, but can't quite
make it.  The third case fan NEVER spins.

I found the service manual on the HP site and it had pretty good
instructions.  I took the beast completely apart.
I confirmed that one of the heatsink fans is stiff and needs to be
I removed from the Notebook the small "case" fan, 5v three wire. and
hooked it to a power supply, it runs very well.   Even before plugging
it in it spun freely.  So... it looks like the motherboard is NEVER
telling this fan to turn on.  I wrote HP, they suggested a BIOS
upgrade from my current KD.M1.80 to KE.M1.45.  I tried doing the
upgrade with the windows utility and I get "This BIOS is not for your
PC".  Will try the dos version next.

If anyone has a ze5155, I'm very curious about that third "case" fan
and to see if it works for others.


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