Where is the thermostat located on a 1991 VW Jetta GL?

follow the bottom radiater hose to where it enters the water pump, you will see a housing. in this housing, that is held on by two bolts is where you will find your thermostat. its easier to get to underneath the vehicle

I would suggest taking this in for repair, you can buy the thermostat at any auto shop for under ten dollars. Finding a auto repair shop that will fix it is the hard part. I found a local mechanics shop that would do the job for eighty dollars, and i gladly paid him The thermostat is located under the Power Steering housing, making it a hard job, you will need two 13mm deep well sockets, a swivel, and an extention, and alot of patience. First release the bottom hose, let antifreeze drain, release three bolts to power steering housing, two in front, one in back, then will be the money shot, you will see the thermostat, from there it's simple removal and putting back together. good luck!

If the car has power-steering the power steering pump and mounting bracket have to be removed to get to the thermostat housing.