2002 Honda Civic Heater Acting Up

Tiny
TCT06412
  • MEMBER
  • 2002 HONDA CIVIC
  • 4 CYL
  • FWD
  • MANUAL
  • 185,000 MILES
I have a 2002 Honda Civic EX. The heater is slow to put out heat, even when engine is warm.

On the highway the heat works great at speed. If I slow down or go into city traffic and do stop and goes and revs go down to say 1000 rpm it starts putting out cold air again.

Sometimes when I slow down the heater doesn't heat but the temperature gauge climbs rapidly to near the red line for a few seconds and then drops rapidly back to normal.

Mechanic has replaced thermostat (twice), coolant, flushed system etc. Still the same problem.

Any advise is appreciated.
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Saturday, March 20th, 2010 AT 8:09 PM

8 Replies

Tiny
LEGITIMATE007
  • EXPERT
I suggest one of two things is mostlikely the problem, the engine coolant temp sensor may be faulty and giving false signals and the water pump itself, is not pushing the coolant into the heater core as it should, causing the fluctuation, but, I just thought of a possible, partially clogged heater core. A pressure test of the coolant system should verify if the the core is clogged. Or even if the radiator is clogged for that matter.
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Saturday, March 20th, 2010 AT 9:20 PM
Tiny
TCT06412
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Hi - the temperature sensor has been checked. Also did a complete coolant flush and pressure check and everything came up good.

Very frustrating problem.

Any other ideas?
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Sunday, March 21st, 2010 AT 5:14 PM
Tiny
LEGITIMATE007
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What did you use to do your pressure check?
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Sunday, March 21st, 2010 AT 8:52 PM
Tiny
LEGITIMATE007
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If all these items have been addressed then the water pump is faulty.
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Sunday, March 21st, 2010 AT 8:56 PM
Tiny
TCT06412
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Hi - I didn't check the pressure. I will have to check with the person who checked the pressure to see how they checked it.

How should they have checked it?

And if you think its the water pump, is there any easy way to check it without just replacing it because its a big job to replace the water pump.

Thanks for your help.
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Tuesday, March 23rd, 2010 AT 7:04 PM
Tiny
LEGITIMATE007
  • EXPERT
A coolant system pressure check will help narrow down and determine if the water pump is faulty
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Tuesday, March 23rd, 2010 AT 9:43 PM
Tiny
TCT06412
  • MEMBER
Finally replaced the water pump (and timing belt) and will wait for the winter to check the heater. However I notice also a problem with the A/C. It works fine, most of the time, but will stop sending cooling air for a while and then start up again.

Is this the temperature sensor? Is this a mechanical sensor on a 2002 Civic EX (at the back top of the engine) or is it an electronic sensor.

Thanks
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Thursday, August 12th, 2010 AT 8:44 PM
Tiny
LEGITIMATE007
  • EXPERT
As far as the a/c. Can be a couple of things doing that. One would be the ambient air temp sensor, (only came on some honda civics. And the expansion valve. I would just bring it to one of those places that "will check your a/c system for free" and have them tell you exactly which one it is. Then you can turn around and replace it your self if possible. And the ect/engine coolant temp sensor is electronic(thermistor). Is a very simple design, basically just a thermometer inside a little housing that creates a certain amount of voltage according to how hot the coolant is.
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Friday, August 13th, 2010 AT 6:54 AM

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