No Heat

I have a 95 chev silverado, and I have no heat, It blows air but its cold air, my truck gets up to 190 degrees after about 5 minutes of driving, but it still blows cold air. please help, could it be
termostat? or too much coolant to water mixture?
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If it was the t-stat you'd have an underheating or overheating engine, too much coolant or too much water same thing.
Sounds like you've got yourself a plugged heater core, or the blend door in the HVAC system is stuck.
Find the two heater hoses running thru the firewall on the passenger side. The line that runs from the back of the intake to the firewall is the feed line, the line that runs from the firewall to the radiator is the return line. After the truck heats up, the lines should be the SAME temperature. If the feed is hot and the return is cold, you get yerself' a plugged core.
Doc

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Low coolant if it's anything like the older trucks. The coolant isn't high enough in the radiator to get into the heater core.
GMC Gremlin

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I'd agre with Gremlin, likely cause is just low coolant, when it gets low enough engine temp stays normal, but you lose heat.......if it gets lower than that, you'lll begin overheating.
Ed

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You're both wrong. Coolant flow to the heater core originates from the intake manifold. The line running to the rad is the return line. If his coolant was low enough to NOT make it into the HC, his engine would be severely overheating.
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Guess I run my truck continuously over heating, consistently, daily, as do others.... from other boards... and other walks of life.... different years.... :thinking:
GMC Gremlin

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Bwahahahahaha!
Doc
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That's a good one. Is this a joke? You do know there is a Water Pump, and it forcing water not only threw the engine, but the Heater Core also! The Engine would have to be so low of coolant that the water pump was pumping AIR. In which case the Engine would be over heating. The likely problem is flow of Hot coolant threw the heater core. Didn't mention any leaking. So it's either plugged, or a Valve to control the flow is stuck closed. If it's the Core, it's better to replace then to flush out. Heater Cores are pretty cheap. It's just changing them sometimes that can take a while. It's better then trying to get it flushed out, only to get the crap into some other part of your system, and or have the core plug up again a short time later, or start leaking all over the inside of your car. This would also be a good time to get your hoses all replaced also.
How about how does the coolant LOOK? When was the last time the cooling system was flushed out? Usually lack of Maintenance is what cause this type of problem. People do the Oil Changes, but really how many out there flush the other fluids? Maybe the transmission. But Brake fluid, and Coolant, even Differential oil, ect.. All are Important, but most never thought about until there's a problem and your stuck someplace.
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JBDragon wrote:

It's no joke - My 93 4.3 just had a leaking heater core. When the coolant got down to about 1/2 capacity the heater would blow only cold air, but there was still sufficient coolant to keep the engine in the normal operating range ( a little high, but still in normal range ). Add coolant and the heat returns to the cab.
BTW - this is exactly the same thing that happened to my 76 Chevy.
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I agree, I have seen coolant levels low enough to cause no heat yet not overheat the engine. Only in cooler temperatures though (winter)
Larry
M Rothwell wrote:

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>Re: "That's a good one. Is this a joke?

I don't know how hilarious the joke might sound but I've had an instance or two in an old vehicle of not enough heat and noticed that the radiator had no visible coolant. Sort of like those old British motorcycles-- If you went out to start one up and there wasn't a pool of oil under it,well it was time to add oil!
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On 15 Dec 2004 18:06:53 -0500, moedemarcus

I would check the "temp door" on the ac / heat controls.
IF your truck is running at 190 then you should have hot air coming out of the vents. Get the truck up to running temperature. Check the heater hoses that run to the heater core...it both are hot then I would suspect a problem with the a/c control head or the temp door.
If one hose to the heater core is hot while the other is cooler then I would suspect the heater core.
First make sure your radiator is full and you have some coolant in the overflow tank.
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What do you do when cleaning out Heater Core??
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Disconnect heater hoses from heater core, shove a garden hose intothe return line, turn the hose on.
Doc

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If the two hoses on the heater core are warm or hot after running to temp, the door on the ducts is shut. Mine had a cracked cable clamp and the cable didn't control the door. I went through the glove box. R.

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