1990 Plymouth Acclaim heater stopped working

First be sure the car is full of coolant before worrying about the heater. No coolant in the heater core can cause a no-heat condiditon, and if you temp gauge was going crazy I would start there. What did the noise sound like? Does the sound of your heater blower stay the same if you select cold or hot? The sound of themotor should be a little different when in hot or cold, this will tell if the blend door is working

Hello -

To better assist you is your model just an Acclaim or is it a LE or LX?

So you don't see any leaks at all? Is your coolant at the correct level when the car is at operating temperature? Please check it

At operating temperature - heater on full high please check both the heater hoses that go into the fire wall to see if they are both hot or is one hot and one not>

Did you look at your cap - how is it?

Do you see any leaks since the car has been sitting?

Is there any smoke out the tail pipe if so what color?

Is the temp gauge still erratic?

Is there any coolant around your water pump or leaking from it

What are the condition of your drive belts - are they still connected and in good condition?

Hello -

The more I think about it since you heard a noise and the temp gauge went a little crazy and the heater stopped blowing hot.......I would definitely check your belts. I know I suggested that already by check them all really good. The noise you hear may have been the belt braking and hitting the bottom of the hood or something, then that stops the water pump from turning... Thus no more heater and the temp will go crazy..... And then only thing that did not allow you to overheat was the cold outside air.......

I may be off here, but definitely check those belts.

Let us know.