[riffsandspliffs]

Please take into consideration, before the roast, that the JDM versions don't have cables that attach to the climate control unit. We have the auto aircon controller that's all electronic that hooks to a motor that controls the air blend door.

And yes, I searched. I found this particular thread to be somewhat helpful.

The thermostat is new, and so is the water pump (saw people asking those questions on other threads).

The climate control unit, when the defrost button is pressed, the motor moves the door to the defrost vents. When the floor/defrost option is selected, the fan moves the door to open the floor vents. When I push the warm button I hear and get nothing.

The knob that selects the temperature doesn't affect the temperature if it's moved to cool or warm.

I took the climate control out today to inspect that all plugs were plugged in, and they were, so it can't be the climate control unit itself.

Going into the engine bay, I located the heater valve. With the cable attached, I was unable to open or close the valve. If I detached the cable, I can freely move the valve open or closed. With the cable detached and the valve all the way open (pushed towards the firewall), I still get no heat even though the hose going to the firewall feels warm to the touch.

So I pulled out the glovebox and removed the evaporator. When I did that, I found two connectors that were disconnected - a 5P and a 3P.

The 5P connector is actually a 6P with only 5 pins terminated. I could only make out 4 out of the 5 colors, but it appears to be a YEL, BLK/YEL, BLU/ORG, BLU/RED, ???

The 3P connector is BLK, PNK, BLK/YEL

I have no idea where these go to, but if you go to the thread I linked at the beginning of this thread, you'll see that the same 3P connector is visible on their JDM harness:

I don't want to tear out my dash to figure out what these connect to. Does anybody have any experience with the JDM climate control heat not working? I haven't been able to find a single BLK-PNK-BLK/YEL 3P connector on any wiring diagrams!

 

[riffsandspliffs]

Sorry to revive my dead no-comments thread, but I'm QUITE certain that the reason I have no heat is due to the OBD-1 conversion and missing the first O2 sensor on the exhaust manifold because it's an aftermarket header with no O2 bung (this would normally be the heated O2 sensor). I can imagine that the lack of this sensor is the reason my radiator fan doesn't kick on as well (but the engine doesn't overheat).

Additionally I am led to believe that due to the missing heated oxygen sensor that my ECU is throwing a code 1. I tried disconnecting and re-connecting the battery, unplugging and re-plugging the sensor, and unplugging and re-plugging the ECU (and its fuse in the engine bay) all to no avail.

I reached out to HAMotorsports (I am running one of their chipped P28 ECU's) and they told me that one 4-wire O2 sensor should be good enough for my setup, but didn't even mention why the ECU is throwing code 1.

Does anybody have any ideas or can point me to someone who's smart on this?

 

[Dave_Darling]

I see absolutely no way for any O2 sensor to affect the way that cabin heat works. The only "heat" for O2 sensors is that some of them have small heating elements in them to get them up to operating temperature faster, because they need to be fairly warm to function correctly.

Nothing to do with cabin heat.

Cabin heat is provided by the heater core, something like a radiator that has engine coolant running through it. Air gets blown through the heater core where it is heated up. That air is then ducted to the correct outlets; either up to the defog vents in the dash, or under the dash to the footwell, or to the vents on the side and center of the dash. Or some combination of that.

So it sounds like you checked the hose going from the valve to the heater core? If that gets warm, the heater core should be warm. Do you have air blowing through the core? Does the heater fan come on? Finally, do the diverter flaps for the defog/footwell/dashboard open up or not?

Your problem is almost certainly in one of those areas. You'll probably have to do some digging to find out what is happening, though.

--DD

 

[riffsandspliffs]

So the plot thickens. I've had the ECU (chipped HAMotorsports P28) unplugged since April 27th. I plugged it back in today and now I get a CEL code 0 (solid light).

To check there's really an ECU issue, I plug in a spare virgin P30 ECU I have, and that ECU tells me CEL code 2.

Sounds like I'll be sending that ECU back to the manufacturer and getting it repaired, as well as installing a new O2 sensor. Likely when I put in my new exhaust.

But none of this explains why my heater doesn't blow warm air. Still looking into that.

 

[joelidge]

The heater is very simple, you have two moving parts: a fan and a valve. The valve turns on the flow of water through the heater core and is located next to the fuel filter close to the center of the firewall. The valve is fully mechanical and uses a cable to change it's position. So either someone routed around the heater core (because it was leaking), the cable isn't connected or broken, or the valve is broken. This should be fairly easy to figure out by looking at the valve while someone turns the tempature knob in the

 

[Dave_Darling]

Another possibility: The heater core doesn't have (enough) water in it. Air pockets do not transfer heat very well like water or coolant do. So if you have air pockets in your cooling system, one symptom is the heater doesn't blow warm air.

Another is that you overheat...

Still worth at least checking!

--DD

 

[mossin_90]

Even with electric solenoids heat should be coming out from one of the vents. Whether it is coming out the defrost position from front windshield or foot area heat should come out.
If no heat is coming out at all, consider removing the heater valve and inspect it fisically for any blockage, IF the HV is clean and operational your heater core may be clogged up.

Dont forget to keep an eye on the floor pans once the HV is on the open position for signs of a leaking heater core, your ECU could be at risk if water leaks toward that side causing electrical problems. Like Power problems with ground connection.

I'm assuming the thermostat is there and in good condition. And that the water pump is also good.