Join Date: Sep 1999
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Re: Heater not working--\'92 K1500 4x4
Thanks for the advice--I was able to fix it today! the first thing I checked was the heater core hoses. Sure enough, the one going to the radiator was cool while the one straight from the engine was hot. I back flushed the core real well, then flushed both ways through the core a few times until it was flowing nicely. However most of the clog actually seemed to be in the hose that ran from the heater core to the radiator. I think it was blocked enough that there was little to no flow. There were plenty of rust chunks in it, and the coolant color was rusty. So, I flushed the entire cooling system as well. The thermostat appears to be working, though it might be opening a bit late. I don't know what temp it's specified for, but it hovers around 180. If anything, it may be sticking closed and not opening up until about 220-230F, becuase once it opens the temp drops suddenly and quickly back down to 180. And now that I know where the t-stat is, I can quickly replace it.
Thanks again for the help! I now have heat!