I am using ArchLinux on an HP Pavilion dv9000t which has overheating problems. I did all what I can do to get a better air flow in the laptop and put a better thermal paste but there is still a problem:

the fan stops spinning when the CPU temperature is low (even if the GPU temperature is high, which is problematic).

I found out I can get the fan running by launching some heavy processing commands (like the yes command). However, it is not a solution because I need to stop this command when the CPU gets too hot and launch it again when the fan stops (so that the GPU does not get hot).

I tried to control the fan using this wiki, but when I run pwmconfig, I get this error:

/usr/bin/pwmconfig: There are no pwm-capable sensor modules installed

Do you know what can I do to get the fan always spinning?

Edit:

The sensors-dectect output is the following:

~/ sudo sensors-detect 
# sensors-detect revision 6170 (2013-05-20 21:25:22 +0200)
# System: Hewlett-Packard HP Pavilion dv9700 Notebook PC [Rev 1] (laptop)
# Board: Quanta 30CB

This program will help you determine which kernel modules you need
to load to use lm_sensors most effectively. It is generally safe
and recommended to accept the default answers to all questions,
unless you know what you're doing.

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no): 
Module cpuid loaded successfully.
Silicon Integrated Systems SIS5595...                       No
VIA VT82C686 Integrated Sensors...                          No
VIA VT8231 Integrated Sensors...                            No
AMD K8 thermal sensors...                                   No
AMD Family 10h thermal sensors...                           No
AMD Family 11h thermal sensors...                           No
AMD Family 12h and 14h thermal sensors...                   No
AMD Family 15h thermal sensors...                           No
AMD Family 15h power sensors...                             No
AMD Family 16h power sensors...                             No
Intel digital thermal sensor...                             Success!
    (driver `coretemp')
Intel AMB FB-DIMM thermal sensor...                         No
VIA C7 thermal sensor...                                    No
VIA Nano thermal sensor...                                  No

Some Super I/O chips contain embedded sensors. We have to write to
standard I/O ports to probe them. This is usually safe.
Do you want to scan for Super I/O sensors? (YES/no): 
Probing for Super-I/O at 0x2e/0x2f
Trying family `National Semiconductor/ITE'...               No
Trying family `SMSC'...                                     No
Trying family `VIA/Winbond/Nuvoton/Fintek'...               No
Trying family `ITE'...                                      No
Probing for Super-I/O at 0x4e/0x4f
Trying family `National Semiconductor/ITE'...               No
Trying family `SMSC'...                                     No
Trying family `VIA/Winbond/Nuvoton/Fintek'...               No
Trying family `ITE'...                                      No

Some hardware monitoring chips are accessible through the ISA I/O ports.
We have to write to arbitrary I/O ports to probe them. This is usually
safe though. Yes, you do have ISA I/O ports even if you do not have any
ISA slots! Do you want to scan the ISA I/O ports? (YES/no): 
Probing for `National Semiconductor LM78' at 0x290...       No
Probing for `National Semiconductor LM79' at 0x290...       No
Probing for `Winbond W83781D' at 0x290...                   No
Probing for `Winbond W83782D' at 0x290...                   No

Lastly, we can probe the I2C/SMBus adapters for connected hardware
monitoring devices. This is the most risky part, and while it works
reasonably well on most systems, it has been reported to cause trouble
on some systems.
Do you want to probe the I2C/SMBus adapters now? (YES/no): 
Using driver `i2c-i801' for device 0000:00:1f.3: Intel 82801H ICH8
Module i2c-dev loaded successfully.

Next adapter: nouveau-0000:01:00.0-0 (i2c-0)
Do you want to scan it? (yes/NO/selectively): 

Next adapter: nouveau-0000:01:00.0-1 (i2c-1)
Do you want to scan it? (yes/NO/selectively): 

Next adapter: nouveau-0000:01:00.0-2 (i2c-2)
Do you want to scan it? (yes/NO/selectively): 

Now follows a summary of the probes I have just done.
Just press ENTER to continue: 

Driver `coretemp':
  * Chip `Intel digital thermal sensor' (confidence: 9)

Do you want to overwrite /etc/conf.d/lm_sensors? (YES/no): 
Unloading i2c-dev... OK
Unloading cpuid... OK

The file /etc/conf.d/lm_sensors contains:

HWMON_MODULES="coretemp"

And the file /etc/modules-load.d/lm_sensors.conf contains:

coretemp
acpi-cpufreq

The command sensors outputs this:

~/ sensors
coretemp-isa-0000
Adapter: ISA adapter
Core 0:       +46.0°C  (high = +85.0°C, crit = +85.0°C)
Core 1:       +47.0°C  (high = +85.0°C, crit = +85.0°C)

acpitz-virtual-0
Adapter: Virtual device
temp1:        +49.0°C  

nouveau-pci-0100
Adapter: PCI adapter
temp1:        +60.0°C  (high = +95.0°C, hyst =  +3.0°C)
                       (crit = +115.0°C, hyst =  +5.0°C)
                       (emerg = +115.0°C, hyst =  +5.0°C)