HEATER WORK PERFECTLY WHEN RUNNING BUT DOES NOT WORK WHEN ID

  • Tiny
  • Kita
  • HONDA PRELUDE

I have a Honda Prelude 2001. I have a heater problem. I've change the fan motor, thermostate and still the same problem. The heater is still blowing cold air. The only time that the heater is working perfectly is when the car is running and when it idle that is when the cold air blows in. Any suggestions?

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Tuesday, November 28th, 2006 AT 11:01 PM

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  • Tiny
  • Bruce Hunt
  • EXPERT
  • 3,760 POSTS

I assume that running means that the car is moving along the road. A couple of things I would look at include:

- What is the temp feel like when the car is moving, does it get nice and hot?
- Have you bled the system to get out any air from the system? The cooling system is a closed system that is comprised of fluid and little or no air.
- What is the idle speed of the engine when in idle? Does it idle at about 750 rpm? It could be idling to slow. Therefore when sitting and reving the engine up to say 2000 rpm does the heat flow through the car?

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Wednesday, November 29th, 2006 AT 7:20 AM
  • Tiny
  • Kita
  • MEMBER

When driving along the road the heater works perfectly. When idle or stopping the cold air blows out.
The temperature gauge shows close to the middle point between hot and cold. Even when it idle the temperature gauge still stays in the same spot. Doesn't go down and doesn't go up either. The problem I noticed is that even though the car is not heated up yet the temperature showing on the gauge are already up in the middle point. Care to give me some advice on what I should do. Got the heater core check out but found nothing wrong with that. No leaking and everything seems to work o.K.

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Wednesday, November 29th, 2006 AT 7:57 PM
  • Tiny
  • Bruce Hunt
  • EXPERT
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Can you answer the questions of my last para on my last post? Remember, we troubleshoot without the advantage of touching, seeing, or smelling what takes place with the car. You are our eyes, fingers and nose.

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Thursday, November 30th, 2006 AT 7:04 AM
  • Tiny
  • Kita
  • MEMBER

I really don't know much about cars. All I know is that the car heaters work perfectly when cranking it up but slows down when it is not moving or when it stops at the lights. The temperature gauge remain the same whether the heat is hot or not.

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Thursday, November 30th, 2006 AT 6:58 PM
  • Tiny
  • Bruce Hunt
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I bet there is a tach in the car. Tell me what it idles at when warm and stopped. When you are warmed up rev the engine to see if the flow of heat returns. This is really simple stuff here.

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Thursday, November 30th, 2006 AT 9:26 PM
  • Tiny
  • Specialchowmein
  • MEMBER

I'm having the same problem with an 02 civic with 100k miles. The car idles normal (about 750) just as it always has, the temperature gauge reads normal right in the middle. When your going down the road the heater blows hot but if your coasting for a while (like down a long hill) it starts to cool off, and if your sitting at idle for more than a couple 5 minutes there is no heat at all. But if I'm stopped and rev the engine for 30 seconds or so the heat starts to come back. Oh and I haven't bled the ac system or done anything to the car since the problem has started.

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Wednesday, May 13th, 2009 AT 11:32 PM
  • Tiny
  • Doomsday012
  • MEMBER

I have the same problem with my Eclipse (2003, 75K Miles). I idle around 750, the heat starts to warm slightly around 2000 but to get it really hot it needs to maintain about 3000RPM.

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Monday, October 19th, 2009 AT 9:03 AM

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