Radiator Fan/Electrical problems

[nixonad]

Hi everyone, this is my first post here after reading the forums for about a year. I have a 1998 with a 996 front bumper and I'm having some issues with the electrics. What happens is when I have the A/C on and the cooling fan on the drivers side front radiator comes on high, I get a faint "click" and for a split second my dash lights dim and the stereo amp will cut out - just briefly but enough to be irritating and enough to make me want to fix this before it gets worse.

It generally only happens at idle, I assume because the rest of the time the engine is making enough revs that it produces enough power for the initial turn-on of the fan. At first I thought it might be an ignition switch issue, but after I replaced it the symptoms came back.

I've read on here that the fan is a two-stage job and that there is a relay for each stage as well as a resistor that sometimes goes bad. I'm guessing now one of these must be the problem, perhaps my fan isn't working on the low stage and it draws more power than normal to go from "off" to "high" rather than "low" to "high"? Anyone have any ideas on what's going on or how to troubleshoot it? Thanks in advance!