Have a 2006 Accord LX 2.4L. Did a coolant change, ran it for bubbles with cap off, fans kicked in a few times, heater seemed to be working fine, topped it off and called it good. Got it on the highway and temp climbed to 85-90%, turned heater blower on hi and no heat, after about 25 min the temp gauge would swing from 60 -80%. Any thoughts??

 

Have you checked again for air in the system

 

I would also strongly recommend a new thermostat.

 

Just did a nice long 2nd air bleed, topped it off, test drive good and got heat back. Probly a trapped bubble in the heater core

 

Probly should start thinkin about a new thermostat though, mines got 169K miles on it

 

Usually you have to turn the heat to full-hot before you change the coolant. That way you don't trap old coolant in the heater core, and you don't trap air in there when refilling. The water valve is motorized, so you have to have the key ON (engine not necessarily running) in order to actually make the valve go open.

 

I replaced the Thermostat and my Radiator in my 2000 Honda Accord LX 3.0 6cyl, I have not had heat for a couple years which everyone who lives in Illinois would know the last couple years have not been bad. This year though, FREEZING!!
After replacing both and flushing out the system, making sure no clogs or bubbles I still have no heat. Could the Thermostat be Stuck? Maybe put in backwards? Any Idea's?

 

Does the temperature gauge on the instrument panel show any engine heat?

If not, then possibly an issue with the thermostat, however, if it does, then I'd start taking a closer look at the plumbing, the heater core, and then the full HVAC system. My 2001 V6 Accord EX put out lots of heat.

 

Agreed, my 99 4 cylinder Accord makes great heat, even during the polar vortex.

 

Also check the air-blend doors. If those are stuck or broken, then it can cause the problem even if the heater core & cooling system is OK.