Hey I have an F22 all maintainence done to it. I did a throttle body coolant bypass awhile ago and the lower radiator is not getting super hot from what I can tell. Also the heat gauge doesn't get too far off Cold if any. It has been single digit degrees here lately and after driving I sometimes have a surging idle.

What I plan on doing is Honda thermostat, coolant temp sensor, and putting the throttle body coolant liines back. Anybody have anything else to add? I have to wait til Monday to go to Honda.

 

Sounds like thermostat is stuck open.

 

If have little heat an you have surging idle your low on coolant... top off your rad an you will be fine... If rad is full...you have a bad thermostat.. But for the cheap cost of replacing the thermostat an hoses you might as well. Just some background info I had the same problem, I have a 91 Accord lx I picked up off an old lady... idle was 800/2200. checked coolant.. bone dry, filled her up an she runs like a charm an heat is perfect.

 

Check your heater valve located by the firewall. It's under the intake arm and TB. Follow the heater hose from the head back, and you'll see it. Those are notorious for being stuck closed. Once that happens, coolant can't flow into the heater core to give off heat.

Those things you mentioned have nothing to do with not getting heat through the vent.

 

Nus dogg is correct my coolant leak was from that exact hose. Right behind Intake an right next to/ below fuel filter. Advanced Auto Part No. 300141. If your driving a CB7. Good luck!