Attached is the cooling system components. The coolant flow is as JimBlake described.

 

If all is ok, it maybe your water pump... These rarely fail on hondas but it could be worn out and doesn't efficiently pump at rpms below 1000.

Or you have a blockage somewhere that is restricting low pressure flow.

 

Awesome thanks for the pics redbull.

The goal this weekend will be to reverse flush it. I live in an apt. and where I would disconnect the hoses (and lose coolant) I won't have access to a hose.

I will be going to my father in-laws shop to diagnose this.

Studying those pics, what does the "coolant separator" do? Is it like a throttle body heater? My GTO has this feature to warm up the throttle body housing to avoid it freezing in cold weather.

 

The coolant separator is also called a partition plate by Honda. The cylinder head was designed to use the coolant separator/diverter to flow coolant around the sleeves to prevent hot spots on certain cylinders.

As noted in this link, "... in the water jacket around the cylinders nearest to the coolant entry point (it's on the timing chain end of the block) there sits what Acura calls a "partition plate." The plate acts as a diverter, forcing the coolant to travel the longest way around the sleeves rather than allowing the fluid to take the shortest path out, which leaves the cylinders on one end of the block unprotected..."

 

Thank you!

I was referring to that tube...it looks like they are calling out a coolant tube called the "coolant separator" but as you pointed out, the arrow is deceiving.

I will keep this post updated

 

Sounds like your heater core may be clogged. This happens when you don't use your heat for a long time, like during the summer months, and the coolant in the heater core starts to gel and plug your heater core. Think it starts heating when you rev it because when you increase engine speed, you also increase the speed that the water pump flows coolant. Higher rpm means higher coolant flow which breaks through the clog. I'm not 100% sure this is your problem but its a posability. Ive seen issues like yours before and it was a clogged heater core.

 

Well here is a little update. Ended up disconnecting the heater core inlet pipe from the "backside of the heater valve and then disconnected the heater core outlet pipe at the motor end.

Shoved a garden hose in the outlet pipe and ran water through it. Then let water fill the heater core and used compressed air (not a lot of psi btw) and let the air PUSH the water out. I didn't notice any dirt or grime coming out of the heater core.

Then we reconnected the all hoses, started the car with the radiator cap off and let it run while filling the radiator cycling through full hot and full cold to divert the coolant back and forth. When the coolant got low we would add some more. While doing this, the heat AT IDLE started to come back.

So seems like between reverse flushing the heater core and burping the system it solved our problems. Wife just texed me saying "I HAVE HEAT!!!!" lol.

I don't know how, if any, air was in the system in the beginning and that it was air bubbles causing this. But it seems a good burnping did the job.

Thanks alot for the help guys! We both really appreciate it.

 

Glad that the problem is resolved and thanks for reporting back.