wireless connection causes excess heat

Specs: Inspiron 1420, Core 2 Duo T7300 2GHz, GeForce 8400M GS, 2GB RAM, Vista SP2, Intel Wireless Wifi Link 4965AGN wireless adapter

I wonder if anyone has come across this.

Recently I noticed my 1420 has been running very hot to the left (where the vent is), especially on AC/Mains power.  Using CPUZ's HWMonitor, it showed ACPI and CPU were operating constantly in excess of 170F (around 80C).  Thinking the fan must have been clogged, I blasted it with compressed air to blow out the dust - no big improvements.

Then one day I took the notebook to a place without wireless connection and I noticed it wasn't running as hot  (also running on AC/Mains) - the temperature dropped to around 115F (45C).  I have been testing this behaviour repeatedly for the past 2 weeks, and to my amazement, it's running much cooler every time the notebook doesn't have a wireless connection or has wireless connection disabled.

Any ideas why an active wireless connection is causing so much heat?  Thx