Hi
I don't think it's a fan problem, but we need evidence of what processes are running and what your CPUs are busy doing.
Here is mine for example… (Diagnostics menu / system activity)
last pid: 85388; load averages: 0.00, 0.01, 0.00 up 171+01:28:55 20:04:35
151 processes: 5 running, 120 sleeping, 26 waiting
Mem: 35M Active, 292M Inact, 258M Wired, 52K Cache, 279M Buf, 3357M Free
Swap: 8192M Total, 8192M Free
PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
11 root 155 ki31 0K 64K CPU3 3 25.4H 100.00% [idle{idle: cpu3}]
11 root 155 ki31 0K 64K CPU2 2 25.4H 100.00% [idle{idle: cpu2}]
11 root 155 ki31 0K 64K RUN 1 25.4H 100.00% [idle{idle: cpu1}]
11 root 155 ki31 0K 64K CPU0 0 25.3H 100.00% [idle{idle: cpu0}]
81695 root 22 0 223M 31856K piperd 0 0:00 0.68% php-fpm: pool lighty (php-fpm)
0 root -16 0 0K 192K swapin 0 2:09 0.00% [kernel{swapper}]
12 root -92 - 0K 416K WAIT 0 1:17 0.00% [intr{irq24: bge0}]
6 root -16 - 0K 16K pftm 0 1:15 0.00% [pf purge]
9196 proxy 20 0 220M 105M kqread 1 0:53 0.00% (squid-1) -f /usr/pbi/squid-amd64/local/et
12 root -92 - 0K 416K WAIT 2 0:47 0.00% [intr{irq25: bge1}]
12 root -60 - 0K 416K WAIT 3 0:30 0.00% [intr{swi4: clock}]
23 root 16 - 0K 16K syncer 0 0:27 0.00% [syncer]
12 root -88 - 0K 416K WAIT 0 0:21 0.00% [intr{irq16: uhci0 uhc}]
46258 root 52 20 17136K 2348K wait 0 0:20 0.00% /bin/sh /var/db/rrd/updaterrd.sh
24844 root 20 0 12456K 2128K select 3 0:13 0.00% /usr/local/sbin/apinger -c /var/etc/apinge
20836 root 20 0 16804K 2304K bpf 2 0:11 0.00% /usr/local/sbin/filterlog -i pflog0 -p /va
59435 root 20 0 14656K 2336K select 1 0:09 0.00% /usr/sbin/syslogd -s -c -c -l /var/dhcpd/v
15 root -16 - 0K 16K - 0 0:09 0.00% [rand_harvestq]
If you can do the same, we can see where the CPU cycles are being used, which will cause the CPU to warm up.