Heat stops working. No heat from heater on my 1999 S10 V6.. I have "burped the cooling system after which I get plenty of heat but eventually it stop working after driving 2-3 days. Should the heater core be defecting I would understand that no matter what I did coolant wouldn't flow through the heater core. But after "burping" the cooling system I get plenty of coolant flow. What would cause the coolant to eventually stop flowing? Thanks, Dave

The most likely reason is that there is air in the system from when you drained down the system. Raise the front up a bit to get air to come out from the heater core. Heater must be on full heat when burping the air out. Continue to add coolant until the radiator fan starts.

Details in the link.

https://www.google.com/search?q=burping+coolant+system

..

What kind of vehicle?

your heater core might be clogged or have an air pocket in system for this, when engine is cool, take radiator cap.off, if you have a no spill funnel to use, then set it up and start.you car and fill your no spill funnel and let it run to burp your system if you dont have one, then take cap off, place a bucket under.your radiator, start your car, let it run till warms up, watch your antifreeze if it starts to burp.and lower, then you had air pockets, it also.helps if you raise the front end of your car to a little if your heater core is clogged feel your heater core hoses, the top one should be hotter then.the other one, if not, back flush your heater core to do this, wait till your engine cools, take off both.heater core hoses then get about 6 feet of heater hose the same size, place about 4 feet of hose on the top heater core line and place a clamp, put this hose into.a.bucket, take the other two feet of hose and place on the bottom heater core line and clamp then take your garden hose and turn water on, into the bottom heater core hose, this will push all the antifreeze and junk out the top hose that goes into.the bucket do this till you have clean water coming out now if you also have.an air compressor, after you have clean water, do the same thing with the air hose, but only use no more then.20psi of air, you dont want to screw the heater core up after you did the air, I.always run more water though it.again to make sure everything is out after you have done this, put the heater core hoses back on, and fill system, start your car, and do as I.said above to burp the system also check your radiator cap, I will always replace them if they.are more then 5 years old, the gasket goes bad, for every psi you lose in your system, you lose heat, I forgot how the math works, but it can be 10 degrees of heat lose do.a.back flush when your eng is cool

When you drain & refill a cooling system air is often traped in places like the heater core. If so the coolant level will appear full before it really is. To burp you need to add coolant till full or just over. Adjust the heater control to MAX heat. This will let full force of water pump to push air out of heater core. Fan speed dose not matter. Next start the motor & let it idle. As it warms up the thermostat will begin to open and close. This is when you should see fluid level drop as trapped air is pushed from system ( add fluid as needed). If this is working right you should fell quite hot air coming from heat vents. If air doesn't seem hot enough adding RPM by pulsing gas pedal should do the trick. And that should do it.

The cooling system most likely has an air pocket and the heater is the highest point so the air collects there and no heat is the result. Burp the coolant system of all air. Sometimes you will have to raise the radiator fill neck higher than the heater core.

air trapped in system, very common. need to burp it.

go to shop with evac/fill equipment so they can burp and chage antifreeze at same time.

go here

http://groups.yahoo.com/group/villagerquest/

Check the Thermostat sounds like it is faulty and is opening when it should be closed. Cheap fix around $15 doing it yourself,

The heater needs coolant in the vehicle to operate. If you're leaking coolant somewhere, and the level falls to low, it won't get into the heater core.

Hi,

You haven't said what is actually wrong with the heat system (there can be several different failures). For the time being I'll assume the fan blows plenty of air but the air is always cool/cold regardless of where the heat temperature selector is positioned.

The most common cause on these cars is a plugged heater core. With the engine at normal operating temperature, feel the heater core hoses (under-hood, mid/lower portion of firewall, access from passengers side). They should both be very warm. If not expect blockage in the heater core.

While a replacement heater core along with a good cooling system flush is the ultimate cure, reverse flushing the heater core will restore heat. This can be accomplished with a garden hose. Disconnect both heater core hoses (not with the engine hot as the coolant get very hot!!) and connect a garden hose. Turn on the water supply to flush the core. Flush the core in both directions (by hooking the hose to one side of the heater core and letting the water run, then disconnecting and connecting to other side of the heater core...). An old garden hose with end cut will work fine if your existing hose will not fit over the pipe (plumb it together anyway you can).

The heater core sits rather low in the cooling system. This means crud in the system will settle there eventually causing blockage. If you flush the core the crud will eventually cause blockage again. Reflushing will work over and over again if saving money is the primary goal.

If this is not the problem, the blend air door is probably not working.

Reply and we'll continue. I don't want to repeat things that have already been done, as $2000 should of covered both things I have mentioned.