2001 dodge caravan heat issue

[paulloc]

my problem is no heat.. if iam driving around the city i have a ltttle heat but it doesn't get hot
and my gauge starts to raise but when i go on the highway my gauge goes down and it doesn't blown warm air anymore someone told me it was the thermstat i bought one but where does it go?
any help please.

[B33p3r]

Follow your top radiator hose back to the engine and you'll find you thermostat housing.