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no heat
12-14-2014, 12:57 AM
Post: #1
no heat
I have a 95 b3000 4x4 if I let the motor warm up before turning on the heat it will blow kinda warm air for about a minute after that its just ice cold I have replaced the thermostate, radiator cap, flushed the radiator twice and replaced the anti freeze! The heater core is not leaking and as far as I can tell I'm not loosing any fluid anywhere else any ideas will be appreciated
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12-14-2014, 12:01 PM
Post: #2
RE: no heat
There are several things to check out. Does it have a temperature gauge? If it does, is it going up to the normal range and staying there? It sounds like the coolant isn’t full due to a trapped air pocket. This can also cause the gauge to fluctuate if the air is near the sender. You could try starting with a cold engine, remove the radiator cap, turn the heater controls to Hot, and start the engine. Let the engine warm up while keeping an eye on the coolant in the radiator. You might want a catch pan under the radiator because you might loose some coolant as the engine warms up. Run the engine until the thermostat opens and the coolant in the radiator is hot. You may have to rev the engine so the water pump can push the air out. Keep topping the the radiator as the air bubbles out until you’re pretty sure you can’t fit any more. Top off the overflow reservoir, replace the caps and see if you have heat.

Another thing to check is the heater controls. Some are cable operated and the cables become rusted and won’t move the valve the whole way to the open position. Others are vacuum controlled and a leak will cause them not to work. Most times it is a hose out on the engine that leads through the firewall to the controls that comes off or gets broken. Sometimes the flaps in the heater box jam, especially if small critters move in and fill the heater box with food and nesting materials.

Please let us know what you find as it could help others.

Thanks for using the forum,
Garner

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12-14-2014, 12:31 PM
Post: #3
RE: no heat
The most often overlooked item I see is actually checking to see if hot water is reaching the heater core. You mentioned flushing the radiator and if that was full of crud you may want to flush the heater core as well. Seeing as the heater hoses use engine coolant one should be the same temp as the top radiator hose (too hot to hold in your hand) and the other should be almost as hot if the water is flowing. If one is cold then you know it's not flowing so use Garner's advice for air in the system. If that doesn't work then pull off both hoses and flush in both directions. If water doesn't flow freely after a few seconds then start looking for a bad water valve or other restrictions. (kinked hose?)

As Garner mentioned, vac hoses and cables can be disconnected under the dash (big feet?) or just broken due to old age. Also, some styles of water valves can fall apart internally (rusted metal) and fail to work or the pieces can block the flow.
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