# 2004 Honda Civic heater blows cold air at low speed

**URL:** <https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875>\
**Category:** Maintenance/Repairs\
**Tags:** civic-sdn, honda\
**Created:** [April 3, 2019, 7:51pm UTC](https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875 "2019-04-03T19:51:28Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![SHERILYNWEINKAUF](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@SHERILYNWEINKAUF](https://community.cartalk.com/u/SHERILYNWEINKAUF)\
**Post date:** [April 3, 2019, 7:51pm UTC](https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875/1 "2019-04-03T19:51:29Z")

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Why does my 2004 Honda Civic heater blow cold air when the speed is under 30 mph, or when idling?

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**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\
**Post date:** [April 3, 2019, 7:55pm UTC](https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875/2 "2019-04-03T19:55:19Z")

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Have you checked the coolant level in the radiator ?

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**Author:** ![vipergg](https://avatars.discourse-cdn.com/v4/letter/v/50afbb/32.png) [@vipergg](https://community.cartalk.com/u/vipergg)\
**Post date:** [April 6, 2019, 8:28pm UTC](https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875/3 "2019-04-06T20:28:00Z")

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Weak water pump ?

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [April 6, 2019, 9:28pm UTC](https://community.cartalk.com/t/2004-honda-civic-heater-blows-cold-air-at-low-speed/137875/4 "2019-04-06T21:28:41Z")

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That can be caused by air trapped in the cooling system.

When the engine is cold, remove the radiator cap and open the coolant system bleeder screw.  
 ![](https://global.discourse-cdn.com/cartalk/original/2X/5/55e36b095708a425e0ad5bf6ddef85acaca7cb3c.jpeg)

Add a 50/50 mixture of coolant to the radiator until coolant comes out the bleeder screw.

Close the bleeder screw, install the radiator cap and take the vehicle for a drive to see if the heater works properly.

Tester