HVAC heat blows warm/hot on drivers side, cool/cold passenger side (warranty issue)

[Daox]

Yep, I have a scangauge II that I measure coolant temp with.

I did test the coolant temp on the hoses last night. I got home with a fully hot engine. I turned the heater to max hot, and max fan. I didn't measure it with a laser thermometer, but I did it with my hand. One was noticeably warmer than the other. The difference was not gigantic, but definitely noticeable.

This makes sense to me if the end of the heater core is plugged up, the hot coolant will only cycle through the first half of the heater core. Well, the first half is the driver's side of the core!





Here is a pic of an actual Mirage heater core.




Looking at this diagram, you can see that the inlet and outlet are on the driver's side. The heater core is #7.





Thankfully, in the event that the flush doesn't work. A replacement heater core really isn't that expensive at all. PartsGeek has them for $66. Not that I want to tear apart the dash though!

https://www.partsgeek.com/gbproducts...ad=47433949812

[Top_Fuel]

When I get home tonight (and the coolant is at 195 degrees+), I will shoot my heater core tubes with a pyrometer and let you know what the temps are. Might be interesting to see.

[Top_Fuel]

When I get home tonight...I will shoot my heater core tubes with a pyrometer and let you know what the temps are.

OK...I did this earlier and here's what I found. It was 25 degrees outside, by the way.

With the car at full operating temperature (190+) and the heat working fine, I pulled into my garage and shut the car off. Within 3 minutes I had the hood open and measured the temperature of both heater core tubes. Both tubes were around 145-150 degrees. I grabbed the hoses and both seemed equally hot. So I think it's safe to say that this is how a "normal" Mirage heater core should behave. Hope that helps.

[Cobrajet]

I didn't measure it with a laser thermometer, but I did it with my hand. One was noticeably warmer than the other. The difference was not gigantic, but definitely noticeable.]

This will be true even if the heater core ISN'T plugged. It sounds like you are getting some heat, so the inlet hose would of course be warmer than the outlet hose. What I would do is turn the heater controls completely off and retry this.

These cars do not have a coolant control valve for the heater that I know of, like older cars do, which would be between the engine and the heater core. Instead, hot coolant is always flowing through the core and temperature control is done via blend doors.

With no air being blown through the heater core, no cooling of the coolant flowing through it will happen. Thus, the inlet and outlet hose temperatures should be nearly the same.

Of course, it is certainly possible that the core is partially plugged. But I would want to make damned sure before I pulled the dash apart or tried to unplug it.

[Daox]

This will be true even if the heater core ISN'T plugged. It sounds like you are getting some heat, so the inlet hose would of course be warmer than the outlet hose. What I would do is turn the heater controls completely off and retry this.

These cars do not have a coolant control valve for the heater that I know of, like older cars do, which would be between the engine and the heater core. Instead, hot coolant is always flowing through the core and temperature control is done via blend doors.

With no air being blown through the heater core, no cooling of the coolant flowing through it will happen. Thus, the inlet and outlet hose temperatures should be nearly the same.

Of course, it is certainly possible that the core is partially plugged. But I would want to make damned sure before I pulled the dash apart or tried to unplug it.

I agree with all of what you've said. I'm pretty sure if it is plugged, its partially plugged. It just kind of makes sense with how the heat is coming and how the core is oriented.