Is it possible to put a heater, or thermostat, in a 1995 dodge spirit that takes less than 20 minutes to heat up in winter? I live in Milwaukee, Wisconsin.
You should have a new thermostat installed.
They do often stick open, which is probably what’s going on. That can lead to a heat problem like your’s and cause the car to use more fuel and not run as well as it could, also.
Replacing the thermostat with a new one should start to heat things up much quicker.
Make sure to get the correct one and a new gasket.
You don’t say which engine you have, but make sure the procedure for purging air from the cooling system is followed after replacing the thermostat and coolant.
There should be a bleeder valve or removable plug on the thermostat housing for this purpose.