So I just brought home a new-to-me 2009 LR3. Sure enough, just like my old one, there isn't any heat on the driver's side. I can cook bacon on the passenger side, but lukewarm at best on the driver's side. So my first line of defense is flushing the heater core, which I had done today at a quick lube place. The guy there actually let some acid sit in there to help break up stuff, and actually did two cycles of that. He said there wasn't a lot of contamination in the core.

Well, it did actually improve things I would say 40 to 50%. Certainly not as hot as the passenger side, but well above lukewarm.

I have a couple of questions:

1. Is it worth flushing the heater core YET AGAIN (at $175) to see if it helps further, or have I gotten as far as I am going to get?

2. The heater core part is quite cheap - around $100 +/- for an aftermarket one. But my mechanic said it was an "all day deal" to replace it due to having to pull the dash, and that it would be $1000 or higher for labor. Does this sound correct?

3. Any possibility that I drive it for a bit before taking the heater core placement plunge to see if it improves? In other words, is there any reason it MIGHT improve?

Thank you!

 

1 - It could help. You can easily DIY this with citric acid. The Mercedes method does wonders. I would never pay someone unless they has a pulsing pressure washer designed for cores, those work pretty well.

2 - True, but I *think* there may be a short cut. You would have to search. I thought it involved cutting the core connections shorter then using some hose. I think one could then sorta slide it out. Really don't recall off the top of my head.

3 - Probably won't improve.

You may also want to verify all the HVAC doors are working correctly.

 

Well, well, well...in doing some more tinkering, I have discovered that when I call for the heat to go to the vents, only ONE vent on the dash generates hot air - the passenger center one. The other three vents - both drivers vents and the passenger vent next to the door, are delivering lukewarm. That doesn't sound like a heater core issue to me.

Thoughts?

 

This the vent layout. In theory both round vents at dash level should deliver the same temperature but I found even in my truck the outer most dash vent is not as warm. But this shows they are one in the same for each side. Also shows the location of the blend door (#7), meaning it supplies all vents so its not really possible to get mixed on the same duct assembly.​​​​​​​

 

thank you so much. I'm officially stumped.

 

More digging... I turned on all heat in the car.

- While the vent next to the passenger door isn’t as hot as the other passenger vent, it’s satisfactory.

- the two rear vents in the console, passenger side hot, drivers side cold.

- the two roof vents in the rear, both are hot

- the very back vents - the third row seat - are both hot.

So... the only cold vents are the front driver’s vents, plus the drivers side console vent in the back seat.

 

Certainly sounds like a clogged core or defective blend door. The rear has its own heater core.

 

So the rear has its own heater core? Or the very rear? As I have the whole one side hot/one side cold thing going on on the rear console vents.

 

The second row ceilings, C pillars and left side "floor", more like thigh, are on their own core.

 

wow! that's very helpful! thank you!