CL9 overheating

Got stuck in a traffic jam on the freeway this evening and noticed the temp gauge after about 5 mins at 3/4 on the scale. Watched for a little bit and it was stable then came down to about half and back up again this happened about 3 times over the course of 10 mins. Had a thought (eventually) to crank the heater and within about a minute, the temp was back at normal. Got through the traffic then and temp stayed at normal until home. I then let it run while stationary for about 2 mins and temp got up to just past half and fans weren't coming on. I then shut it off.

So I'm thinking the fan motor or fan switch isn't working - thoughts?

Given the regularity in temp variation I am wondering if the AC fan kicks in at higher temp and that's what has controlled the temp from a total overheat. Pump, thermostat, radiator would all be working as intended given the normal temp when driving (coolant is obviously flowing to and from the engine)

Connect your fans directly to your battery by using jumping wires and see if they kick over
if they do
It might be a relay problem

also check temp stat