Front left heating up

Hi Everyone,
Just seeking advice in relation to an odd situation. The front left of the engine bay is heating up quite a bit in comparison to the right side. You can feel the heat in the left panel and bonnet. The issue is new and commenced after not using the Jimny for 6 weeks. Initial drive was fine, but after 10km, sitting stationary and turning the aircon/fan off the revs started creeping to 1800 then to 2400. The revs would drop back to 1000 when turning the aircon on again and then climb back up with the aircon/fan turned off. Only happened earlier this week. But the front left is still hot even after a short drive.

The water temperature appears fine. There is an exhaust smell blowing out to the left of the engine bay with it being considerably warmer there but no noise different than normal.
Power steering fluid is black and the steering is becoming slightly harder to negotiate (my mate told me to toughen up). No coolant loss apparent. Drive belts recently changed with a slight squeak from the alternator. Maybe I damaged something with the belt change?

Any suggestions will be appreciated.

Hi Lambert,
Thank you for the reply and apologies for the delay in getting back to you. When the problem started, the front left of the engine bay started heating (when seated in the driver's side), the same side as the exhaust manifold. It was quite odd and did this a few times although the temperature gauge never indicated anything other than normal. When feeling the external panels on the intake side, it was significantly cooler.
The problem (as well as the gradual increase in idling) appears to have stopped. I wonder if it was to do with the fact that we were away for 6 weeks and during the time the Jimny sat through a cyclone. I wonder if moisture made its way into the engine bay resulting in the strange idle and whether something temporarily connected the heat shield to the exhaust manifold and conducted the heat this way?
Nevertheless, it appears fine at this stage. Thank you for your input.

One final thing, in addition to the previous heating issue, and intermittently for a couple of months prior, when standing near the exhaust manifold, a smell of exhaust fumes would linger. Would anyone know where this could come from? There aren't any loud sounds indicating a crack in the exhaust system that I can hear. And yet again, after the most recent drive and sniff, the smell wasn't there.
Cheers.

exhaust/manifold when cold get underneath
Grab the down pipe and see if theirs any movement on manifold joint
The welded nut part on manifold rust through and compromise the seal

Thank you. I have noticed fragments of rust around the engine mounting point under the exhaust manifold. I will look into it.