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The Audi Doctor
The Audi Doctor, Technician
Category: Car
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Experience:  Over 30 years experience, 17 years with Audi, Factory trained
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My heat doesnt work in my 2005 Grand Caravan...just blows

Resolved Question:

My heat doesn't work in my 2005 Grand Caravan...just blows cold air. What's wrong?
Submitted: 7 years ago.
Category: Car
Expert:  The Audi Doctor replied 7 years ago.

Thank You for choosing Just Answer for your query. Yes, I can help you.

Your symptoms could be consistent with a plugged heat exchanger or heater core.

The amount of flow going through the heater core is very hard to determine and the apparent resistance can be deceiving. The core of the heater core is not only a group of tubes, but the tubes are filled with a mesh material similar to steel wool. It takes very little resistance to overcome the low pressure from the engine. On a properly functioning system the temperatures of the two heater hoses is typically fairly close with only a slight reduction in temperature. Typically when I replace restricted heater cores the coolant appears perfectly clean. When I cut open the core and then it has a chance to dry out, small particles consistent with the appearance of sand are found in the mesh material.

I suggest you try to confirm the core blockage as follows. Fully warm the engine to operating temperature. Shut down the climate control system so that no air flows through the system. drive the vehicle at slow speeds or run at an elevated idle for a few minuets. turn on the defrosters at maximum heat. If the heat appears hot at first, but then rapidly diminishes, the core is likely the cause. If however there is no heat a temperature blend door, a cable or sensor may be at fault.

If there does appear to be a restriction in the heater core to further confirm, you can try back flushing (flushing backwards) the heater core with a water hose. Observe the expelled water, especially in the beginning, for any evidence of contamination. This may also give you increased performance, but typically will not be 100%.

I hope this helps clarify the problem and aids in your diagnosis. Should you decide to accept my answers please click the ACCEPT button.

Stay warm!

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