Non-Maro Problem - Heater Core?

Wife has an 04 Kia Sedona with the 3.1 liter V6 (I think that's what it is, I know it's a 6 anyway).

ANYWAY, the heater totally SUCKS, and I don't ever remember it being that bad... slightly above warm after .5 hour of driving... No coolant inside (of course the damned thing is so full of toys and shit that you'd never really be able to tell). I know it's a 6 so it'll take longer to warm up than a V8 (obviously), but I would think that after 5 minutes of driving it should be blowing warm enough to make you back it down a bit.

Question: How do I tell if the heater core went, or find out why the damned thing is so weak if the HC is ok?

(To clarify... it won't even melt ice on the windshield... THAT's how tepid it is.)

A long shot but what is the temp outside and is the engine getting up to operating temp? If it is VERY cold and the engine isn't getting up to temp, that would be your problem, solved by putting cardboard over the front grill to keep the engine heat in.
If the engine is getting up to temp then you probably have a heat diverter valve that is stuck. The valve cuts off coolant flow to the heater core when heat is not selected and when they fail they won't move. The diverter valves were used to make the A/C systems "more efficent" as in R134 doesn't cool near as well as R12 so they were trying to get rid of any heat source inside the car that they could.

Hmmmm... new info, If you put the dash vent on high heat, it comes out hot, but if you put it on the feet vent on high heat it's cool. The back heat is always cool too.

The water temp gauge indicates that the engine is getting up to temp, I had thought of trying the cardboard, but after watching the gauge I'm not sure if it'll help. (Of course with the problems we've had with this thing, I'd not be surprised if the temp gauge was wrong.)

Where are these heat diverters and are they replaceable by themselves or are they part of an assembly? I would have to drain the coolant system to replace them?

On a GM car it is in the engine compartment plumbed into the heater hoses. It is a plastic piece about 2" in diameter and has a vacuum line going to it.
If you get good heat in the vent position but not in the other positions it may not be the heater valve. When in other positions is the air flow volume the same as in the dash vent position?

Not sure, now that I think about it seems like it may have been weaker through the heat vents than the dash vents, but I have to check. I'll have to swap cars and drive it a bit and check it out. I'll get back to you...

I've come to the descision that all V6s are lousy on heat, every one I've owned.

Something else that comes to mind is my Buick was set up with a fresh air vent in the cowl that was always open. On brutally cold days, the heater motor would just channel the cold air directly on my feet. This was apparently a common problem in the design of the LeSabre/PA, and the "fix" was to put something ove the opening in the cowl. I just blocked off the problematic vent and the heat improved on all the others. :2cents:

However, you lost me on the temp reading of the guage, is the engine temp acutally low? 'Cause as Morley eluded to with the cardboard, usually everytime I see a car crusing like that means someone's too lazy to replace their thermostat.

Temp guage says engine temperature is ok... unless the damned gauge is broken.

I'll have to look at that cowl vent - see if it has one.

My 86 blazer's heat was ferocious (EDIT 2.8l V6 - total pussy). This thing... I just don't remember it being that weak. I mean like, it won't even melt the ice on the windshield.

Drove it to the store the other night, about 6 miles each way... the heat was just getting luke-warm by the time I got home.

I've been stuck using the wife's Taurus, which during the last few weeks when it was brutally cold finally started putting out decent heat about 30 mins, into my 45 min. trip.

Maybe it's just the way the damned thing was built then... Usually the local driving is no more than 20 minutes... and the temp gauge is just starting to perk up at that point.

Piece of crap... last foreign vehicle I buy. Last NEW vehicle I buy too.

Well, to be sure, you could get a hydrometer, under 2 bucks and chekc the antifreeze out and elminate that.

Then you could check the thermostat by starting the motor, cold, and keep you hand on the radiator return hose. Once the temp gets within a few degrees of normal, then the 'stat opens, and you'll feel water start to flow, and the hose get warm.

I know with the Taurus, I checked everything ut and it was fine, then I referred to our local gourus over in that section, and came to find that there is a problem with them like Morley says here about running a bypass valve on the heater line.