A4 overheating

My sons 96 A4 is getting close to the H on his temp gage I checked the hoses and the drivers side is hot and the pass is cold the heat works well.. How should I go about repair.

Thank you in advance. My A6 4.2 is over 150k and running strong!!

most likely a thermostat, you might wanna change the timing belt and water pump , as the parts are right there. good luck

Thanks,

The guy who replaced all the above used the green antifreeze I think it clogged the radiator!

Thanks for your help!