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post #1 of (permalink) Old 12-12-2003, 11:19 AM Thread Starter
 
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Heater not working--\'92 K1500 4x4

Hello,

I've got a '92 Chevy K1500 4x4 with a 4.3L V6 and 5-speed tranny. It's been parked for a couple months, and I decided to drive it the last few days since it's been sitting. However, now the heater blows weak to no heat. The fan works at all speeds, and I can feel a very weak temp change when I change the temp on the dash LCD display, but no hot heat like it used to. What are the possibilities (stuck thermostat? clogged heater core)? If it's the T-stat, where is it located? If it's the heater core, is there a good way to unhook the hoses and back flush with a garden hose? It's about 0F degrees out right now, and a little bit of warmth on my 30 minute drive to work would be wonderful!

Thanks,

Shawn
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post #2 of (permalink) Old 12-12-2003, 11:27 AM
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Re: Heater not working--\'92 K1500 4x4

Shawn,

Ckeck the heater core flow first. Feel the heater hoses(after the vehicle has warmed up) if 1 is hot & 1 is cold the you have a restriction in the heater core, hoses or the outlet from the intake.
The outlet in the intake has a restrictor in it, therefore plugs up easily.
The thermostat is located in the front of the intake.
follow the upper radiator hose

Matt
post #3 of (permalink) Old 12-12-2003, 12:25 PM
 
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Re: Heater not working--\'92 K1500 4x4

Yah, check the heater core first.
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post #4 of (permalink) Old 12-12-2003, 04:17 PM
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Re: Heater not working--\'92 K1500 4x4

What does the temp guage read when you've been driving for a while? If the engine never gets hot, then you'll have no heat. That would indicate a thermostat stuck in the open position.
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post #5 of (permalink) Old 12-12-2003, 08:24 PM Thread Starter
 
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Re: Heater not working--\'92 K1500 4x4

This is the first winter I've had the truck, so I don't know what it "normally" warms up to but here's the scoop. The engine temp gets to around 180F, or a hash or two below the mid point of the temp gauge. The engine seems to take "forever" to warm up. I have not checked the heater core hoses, but that sounds like a good first start (I just have to find them). Does 180F sound acceptable, or does that sound like the T-stat is stuck? I'd rather that be the issue than a clogged heater core! Another possibility I just thought of is that a mouse could have built a nest in the vent system. First I'll check the hoses though. Thanks for the help!
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post #6 of (permalink) Old 12-13-2003, 06:15 PM
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Re: Heater not working--\'92 K1500 4x4

My truck always runs 180 whether it's 100F or 0F outside. I guess that's thanks to the 180F thermostat though. [img]images/graemlins/smile.gif[/img] But yeah, that's a normal temperature.
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post #7 of (permalink) Old 12-13-2003, 08:20 PM Thread Starter
 
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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!
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