Originally Posted by dieseldan44

toybul,

I took my heater core out of the '82 because I was replacing the evaporator. The new heater core does make a big difference, at least in my case. The fins were not blocked. The evaporator had enough dirt to plant a garden.

Things to check -
- unplug monovalve electrical connection - bad monovalve = lukewarm heat
- check aux pump and make sure its doing its thing

To be fair, at the same time I replaced my heater core I replaced my water pump and radiator, so my experience is not completely scientific.

BUT, it too the car heat from lukewarm to burn your face off...passengers beg for mercy.