Where is a heater thermostat located on a 1999 Pontiac Montana?
The thermostat is blocked by the intake manifold. It’s not an easy job and most likely your are trying to fix a tempature gauge the fluctuates. If that’s true then you need head gaskets. The 3400 motor is known for them going and the first indications is the temp varying and missing coolant that has not leaked on the ground.
