First time posting. I have looked around quite extensively but have not been able to pinpoint a similar topic. I have a 1985 GL wagon that runs great. Everything was working great until two days ago. I had not driven it for a week and a half because I was out of town. The temperature hear in Colorado was below 20 and as low as -10 for most of this time. Now once it gets warmed up to operating temp the heater does not work. The hoses going into the heater core are not particularly warm and when I squeeze them there doesn't seem to be anything in them. It will also start to over heat but then go back to normal temp occasionally. I checked coolant level and filled to maximum. Has anyone else experienced this or have any insight? I plan on getting a block heater soon but have a feeling that won't change much except for ease of starting. Any help is appreciated. Thanks, Noah.