Still trying to troubleshoot the problem bu I don't know much about the cooling systems.

Ok so here's where I'm at with this:

Both fans are working where car is running

Left the car idle for 10 min and did not overheat

Coolant full in both reservoir and rad

The overheating doesn't occur in one shot. This morning driving to work I had the AC on all the way and the needle stuck just 1 click below the middle (normal). So the heats up until that poit and the cooling system works great. But after say 20min of driving at normal temperature all of a sudden te needle starts creeping to the H. If I turn offthe AC the needle settles back to the normal temp. When I say turn off AC I don't mean turn the heat on... Just turnin the AC is good enough.

Was at the garage to balance the tyres... They saying the thermostat is probably the problem. Does that seems right?