I have a 2004 Honda Civic EX - My temp. gauge is at normal all the time, I don't have problems with over heating. When I drive my car I get heat out of my vents, but when I come to a stop or slow way down the heat turns cold. Here is what I have done....

Checked fuses - none look blown or burned

Replaced Thermostat

Had local Honda Dealership put car on Diognostic deal and it is NOT throwing any codes to say what is wrong.

Checked Radiator level for antifreeze - Full

Antifreeze reservour level - Full

I have asked around and some people think that it might be a bubble in the line. I would think so too but I have had this problem since the end of last winter (2011 winter) and if it was a bubble in the line you would think that it would have come up by now, maybe I am wrong please advise me if I am wrong in my thinking. I never have done anything about it till now since spring & summer came and I didn't need the heater. Also the car has not shown any signs of being in distress as far as over heating or any of the fluid levels being below normal. It is now fall and the temp out side is getting colder and I really don't want to spend all winter long with no heat in my car.

Can someone help me out to give me more ideas of what this problem might be so I can have my mechanic start checking things so I don't have to pay out alot of money to get everything replaced as well. I feel that I am getting the shaft when I call around to mechanic shops they see a girl come in the door or on the other end of the phone they want to hike the price up and sell me a bunch of crud! I just want a car that has a working heater and I am frustrated that I can not get this figured out....

Please Help!!!

 

Did you check the level in the radiator itself or in the plastic tank on the side? There is a difference. Park on level ground, wait until the engine is cold, and take the radiator cap off. It should be completely full to the top.

 

Yes I have checked both the radiator & the plastic jug thing (reservour) next to the radiator and they are both FULL.

 

Next check that the water valve on the firewall moves to fully open when you set the dial to full hot.

Flushing the heater core (disconnect the hoses from the engine, and flush in both directions with a garden hose to check for free flow) should be considered.

The water pump could have corrosion damage, this is very rare unless the system has been operated with plain water or never changing the coolant. Old coolant eventually turns to an acid.

 

My niece just told me of this same problem with her 04 civic. My daughter-in-law had the same problem with a Nissan Altima. I found a forum on line and found that yes it is air trapped in the coolant hose going to the heater core. They gave instructions on how you had to jack the front of the car up a specified number of inches to bleed the air from tair from the system. I did this and it worked for a couple weeks and then the problem came back. The air has to come from somewhere and after checking on line again, found that if the problem returns, its either a blown head gasket or a cracked head. She gave the car to her sister and she ended up putting a new engine in the car. Don't know if this helps but just thought i'd let you know about my experience with this issue.