I can't get any heat, only cold air. I flushed the heater core and there was no blockage. The temp gauge reads normal. Is there a valve controlling the water flow to the core, and if so where is it located? Any other thoughts? Thanks
You have air in the system!! you have to unbolt the filler tank and lift it 5 inch higer first. then loose the right hose on the heater core( this hose have and hole to bleed the system) and then put antifreeze until the antifreeze will go out of the hole then re install the hose to the heater core, then ajust the level correcty
have fun
jean-martin
Are you sure the thermostat is working efficiently? If your getting a little heat when the car is idleing in traffic, but this goes when you start driving again, it suggests the t'stat is stuck open, therefore no temperature can build. When you flushed the system, could you confirm the flow of water through the heater radiator? Was it passing through easily or just a dribble on the point of exit? is there any heat delivered from any of the other heater settings, e.g floor/screen/face vents? If you can get heat from one of these positions it may suggest a heater box issue. There is of course a slim possiblity that the impeller on the engine water pump may have become loose and ineffective. See how you get on. Good luck
After reading your reply only one more thought springs to mind. You mentioned how water flowed freely through the heater when you flushed it and that now the engine is up and running how only one of the hoses gets hot. If the second hose from the heater rad remains cold, it might possibly be you have an air blockage due to the system not having been bled correctly, this is not an uncommon symptom and it affects all makes and models. One thing to try when the engine is started but not up to normal working temperature I hasten to add, gently ease back the return hose from the heater radiator, ensuring the radiator filler cap is removed at this time. The escaping coolant will confirm the effective flow through the system and in addition will allow the escape of any possible trapped air from the system at the same time. I'm unaware of a heater control valve on your model, however I have seen these types of valves creeping in and out of production over different years and models. Ford Ka's for example are very common for failures which is an inexpensive switch in the dashboard. If you can confirm the presence of such a switch in your model then I think your almost there. y fingers are crossed for you.
Install an auxillary water pump and it will solve the problem. Later cars had a nice pimp that can be fitted. Just find a switched power source for it. Common problem solved.
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Air
Temperature Control Blend Door Failure No Heat or no AC (dependes on
where door sticks)
In
all modern cars there is a tiny DC electric motor driven gear drive
that moves a plastic door that blends heated and cooled air from the
AC and the heater core, this is called (interestedly enough) the air
temperature control blend door actuator. The motor that moves this
door fails because the door starts sticking from warping, most common
complaint is no heat but it can be no AC as well. To replace these
parts (blend door and blend door actuator) you must remove the entire
dash from the car. Always have this problem confirmed by a dealer or
qualified repair shop as it is a very expensive repair.
Other causes of no heat in the cabin are engine thermostats that are stuck open (engine runs cold) or air bubbles in the cooling system.
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The temp gauge always displays in the normal range. Also, a garden hose runs water easily thru the heater core. Only one heater hose gets hot when the engine is running. This is why I thought I might have a stuck heater valve, but I can't verify one exists for the '96 A4. I would suspect a bad water pump or thermostat if I was having water temp issues, but the rest of the cooling system is fine. Any additional thoughts are appreciated. Thanks for the reply.
I have a 98 a4 2.8. It blows cold air with the heat on. One of the hose entering the core is hot and the other is cold. I took the hoses off and blew air through the core with no problem.
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