no or low cabin heat. on 2001 Volkswagen Jetta

No or low cabin heat even though the coolant temp gauge indicates normal operating temp(190 deg F). Heater core back flushed last year, thermstat replaced.

Asked by for the 2001 Volkswagen Jetta
Your heater core could be going bad, but that typically would cause it to leak somewhere. Also check your coolant level. If it is low, it could cause your heat not to be optimum.