So, my wife's van isn't getting hot despite running for quite some time. On occasion, it may finally begin to produce hot air after 15 minutes of driving. If it matters at all, the engine temp got over the summer related to a stuck thermostat and it was fine after that. I'm not a heating or cooling system guy at all to know if one would have caused another. Is this likely a bad heater core? I haven't noticed a coolant smell at all. Blower is fine-the air just isn't getting warm except the rare occasion it may start warming up after driving several minutes even after the engine temp is fine.

Thanks for any suggestions you may have.
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Put another stat in it.
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First check to see if it is full of coolant,not just the expansion tank take the radiator cap off and look.
Be careful do it with the engine cold.

Check the temp gauge, if the temp is not coming up the thermostat could be stuck?

That's some place to start.
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Sounds like a thermostat and it's a cheap fix if it works.
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Does Lowe's sell anti-freeze?
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Echoing others who've posted already...

Sounds like it could be related to your thermostat.

The thermostat is going to open up, allowing coolant to flow freely to the radiator and heater core once the thermostat reaches the appropriate temp. This typically happens within a few minutes of starting the engine.

If it's stuck in the open position it is not allowing the coolant to increase in temperature properly because it is running through the raditator from the moment you start the vehicle.

This may account for why after a prolonged period of driving the heater appears to begin working again. It is simply requiring a much longer period of time for the coolant to attain a temperature sufficient enough to provide the heat into the cabin.
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The reason I replaced the thermostat over the summer was because it stuck closed and had high pressure behind the thermostat as though nothing was getting through. You could squeeze the hose going into the radiator very easily, but the line going into the engine was as tight as could be.

It makes sense, but then it doesn't because I just changed it and wouldn't it seem unlikely to already be bad again so soon.
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Could have just been a defective part and since it was summer never noticed the heating portion of things.
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What model is your van? And does it have a temperature sensor on the dash?
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Dodge Grand Caravan-it shows the temp gauge in the dash. Prior to replacing the thermostat, it was as high as it would go and one day I even stopped and pulled off several times to cool down on my way home to hopefully keep from doing any damage. Now, it'll idle/run in the medium range of the gauge, so the coolant is obviously passing through the system.
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Does it have automatic climate control?
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:-) That is so wrong and so funny!
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I would check the antifreeze first. My wifes car did the exact same thing last year and it was a combo of to little and to watered down antifreeze. i topped it off with a little straight antifreeze not watered down and it fixed it instantly.
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It might be a good idea to have the cooling system completely flushed out. Also, maybe have an engine compression check done just to make sure there isn't an issue with a head gasket or cracked/warped cylinder head. Is the water pump working correctly?
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I'm not going there for it. :-)
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I agree it sounds like a thermostat
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I hadn't thought of this. I think I've got one of those gauges in my tool box and see what the concentration is.
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I had a Ford Explorer where I had to replace the thermostat every year because it wouldn't heat up when the weather turned cold. It didn't make sense, but it worked. :-)
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Actually got around to checking out the coolant level and seems pretty low. Going to do a complete flush and fill tomorrow and see how that works.
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:-)
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