2003 Honda Civic Heater Not Working Properly

The heater in my 2003 Honda Civic only heats up after continuous
driving for 15+ minutes. Additionally, even after highway driving for
2+ hours, the heater sometimes blows cold air when I slow down and do
city driving.

Any ideas?

 

when did you last check the coolant level in the radiator? it needs to
be full to the top. the expansion bottle needs to be to the "max" mark too.

 

Well, to the "max" mark when fully warm. That's why it's an 'expansion
bottle.' ;-)

Mike

 

no, it needs to be at "max" when cold. that line is less than half way
down the bottle. the /rest/ of the bottle is for expansion.

do you keep your oil at the bottom line or the top?

 

Most likely the coolant level is very low in the radiator.

As others have pointed out, check this first. Driving with low coolant
level will damage the engine.

DO NOT rely on the reservoir level as a judge of coolant level! Check it in
the rad once the engine is cold. It should be right up to the bottom of the
rad cap; that rad cap should be dripping wet.

 

My sister had that in her Prelude. It turned out to be a stuck open
thermostat.

Bruce.

 

Coolant level in expansion bottle is at max when cold. I already
checked that. Oil level is between the top and bottom lines. Oil has
been completely changed since the problem was first encountered and no
difference.

I’m beginning to think its an electrical problem or possibly the
thermostat

 

Then it's the thermostat.