Rabid Addict

This is a manual single climate control, not dual climate. A/C works perfect, comes out all vents cold when selected. mode selector works perfect(can select floor, defrost, main vents). Heat does not work on drivers side vents at all(it is cold, but still blows air) Heat works mildy on passenger side (moreso on most passenger side vent, there is a noticable difference in temperature between the two center vents) and the passenger half of the windshield will defrost ice. The door blend actuator on drivers side seems to function fine when switching temp from hot to cold and vice versa it rotates fully. The hvac test from the display returns no fault codes. Replaced thermostat and filter, so all thats left is the heater core? I just am curious if there are any more door actuators in there that would restrict the heat from entering all the vents since there is a noticeable difference between them.

TyGuy88

I would start by ensuring the radiator and coolant reservoir are topped off. You'd be amazed how many we see that the coolant level gets overlooked. I am not sure it the 03s still have the cable actuated valve on the coolant line leading into the heater core but that would be something to check. It also might not hurt to jack the front end up and burp the system. there may be air trapped in the heater core.

Rabid Addict

Thanks, I'll look into each of those things. Although coolant was one of the first things I checked, that was months ago when the problem first started.

Assuming it is one of these or the heater core/resistor I should be able to solve it here shortly, my real concern is that I go through all of this trouble and it be something else because the vents are behaving differently. If the same heat were coming from all the vents instead of just the passenger side it wouldn't be a problem at all, is it common for a partially functioning system to distribute the heat like that? I would think that if the core wasn't heating adequately then all the vents would have the same loss instead of just half of them.

Rabid Addict

Still same symptoms. The coolant levels were all fine, but I went ahead and flushed the system anyway. I also flushed the heater core directly to see if it was clogged. The flow seems fine and there are no leaks. The valve is cable activated by the door blend actuator and it functions fine as well. Both the inlet and outlet hoses to the heater core are hot when the heat is on.

Since the heater core doesnt seem to be clogged and definitely isn't leaking, and the blower and actuator motors seem to all be functioning from the outside I think the next step is to tear apart this dash and maybe try to open this whole contraption up, maybe I'll find a broken or stuck linkage or door somewhere?

I did find some good diagrams online of the HVAC system, but nothing as far as the interiors of the ventilation.

swc65

Not sure if your still checking this forum. Did you ever resolve issue? I’ve got similar issue with 2014 CRV. My problem is reversed, I have heat on driver side. I performed a reverse flush with CLR chemical per technical service bulletin from Honda 14-063 and it improved heat on driver side. I not get 150F on driver side with ~112 on passenger. But I’m still puzzled that a partially cleaned heater core will result in uneven cabin heating. My heater core had good flow in both directions.

swc65

Not sure if your still checking this forum. Did you ever resolve issue? I’ve got similar issue with 2014 CRV. My problem is reversed, I have heat on driver side. I performed a reverse flush with CLR chemical per technical service bulletin from Honda 14-063 and it improved heat on driver side. I not get 150F on driver side with ~112 on passenger. But I’m still puzzled that a partially cleaned heater core will result in uneven cabin heating. My heater core had good flow in both directions.