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

[pilchardfish]

It would be good to know if the corrosion is on the inside or outside of the heater matrix / core.

Thanks pilchardfish!

Okay, I have man on the inside Well, I know someone at the dealer. I've asked the question and apparently it's corrosion on the inside. There's some kind of central strengthening bar inside the heater core / matrix that I guess helps keep the thing rigid and give it strength; this is the cause of the corrosion which slowly builds, and then causes the flow of water to the drivers (or passengers) side of the heater core to be blocked, for reasons you've already established earlier in the thread (it's vertical and I guess clogging happens from the bottom upwards).

Mitsubishi have fixed the part so this strengthening bar thingumy doesn't cause the issue any more; but for cars affected, I guess there must have been a batch of them with this manufacturing fault. Not all Mirages, but some.

Think that's as good as I'm going to get without hanging around the garage in a couple of weeks to see what they fish out from the dashboard! But hopefully that gives you more to narrow it down.

I suppose the corrosion cleaner you're experimenting with earlier in the thread might help shift the deposit and unclog it; but I guess if that was a proper fix, dealers would do that, rather than spend a day on labour. From what I know, warranty work pays - but not that well - so if there was an easier / quicker way I guess they'd do that!

Said earlier, but I'm told it's a day of work to do the job, and can run into two days depending on quirks and whether the mechanic has a good day (or a bad day) with getting everything out of the dashboard, as the steering column has to be dropped and I guess it's just a humongous beast of a bit of the car to lift out of position, given all the things that will be hooked into it, and need to be put back. Plus imagine if you forgot to click something back into place ... could undo a few hours work if you only discover it later on!

Hope that helps guys

[Top_Fuel]

I did find this blue tube in there... I'm guessing that is the aspirator, but I really have absolutely no clue.

Attachment 10596

Hmmm...it's probably unrelated but check out THIS video of a 2014 Outlander with weak heat (fast forward to 3:30). It turns out there was a wire improperly installed and blocking the heater core flap from completely closing.

[Top_Fuel]

...apparently it's corrosion on the inside.
...corrosion which slowly builds, and then causes the flow of water to the drivers (or passengers) side of the heater core to be blocked

Thanks again for the info! That is great!

So are you going to have yours replaced?

[01-7700]

Hmmm...it's probably unrelated but check out THIS video of a 2014 Outlander with weak heat (fast forward to 3:30). It turns out there was a wire improperly installed and blocking the heater core flap from completely closing.

I watched that in my quest - I think the guy said the wire was there due to an earlier core replacement.

[pilchardfish]

Thanks again for the info! That is great!

So are you going to have yours replaced?

No probs. Yeah, it's under warranty, so it's going in in a couple of weeks time. I guess they'll do a quick diagnosis before they actually rip it apart; but based on other Mirages having the same issue, it sounded like it was a given that's the problem and that's what they'll do.

I'm 2.5 years into my 5 year warranty; weirdly the original (non-facelifted) Mirage only had a 3 year warranty, then to compete with the Koreans who were all doing 5 and 7 year warranties, they upped it to 5 years just before I bought mine. So probably a good time to get it sorted, as I've another 2.5 years left of the warranty to ensure the issue hasn't come back

Off topic a bit, but I've no idea how folks still buy cars in the UK that only come with a 2 year manufacturer warranty, with the third year being at the grace and goodwill of the supplying dealer (eg they wriggle out of everything). There's a few manufacturers that do that still - reliable marques - but even so, Mitsy are reliable and here we are with heater problems! lol

[Eggman]

Hey pilchardfish we would sure like to see pictures of the job (before, during & after if possible) and most of all, we would like to see this corrosion, even if it means disassembling or cutting open the matrix/core.

[pilchardfish]

Hey pilchardfish we would sure like to see pictures of the job (before, during & after if possible) and most of all, we would like to see this corrosion, even if it means disassembling or cutting open the matrix/core.

Best I'll be able to do is relay the outcome of what they changed and any comments they make; as it's under warranty and I'm not paying for the work or the part, I'll not get the part to take home. I believe they have to keep them for inspection by MMUK if asked for it. A relative used to work in service, and apparently they do spot checks to make sure garages aren't just replacing parts for the sake of it in order to make money off warranty. So I don't think I'd be able to ask for the part to then chop it up! Sorry I once had a Colt, and the little bulb blew behind the hazard warning button; you'd think that would be a throw away item, but apparently they asked for it to be sent back to HQ as it was a rare issue, so they wanted to check exactly what had happened. Which I guess makes sense.

But if I do get anything extra useful, I will share

[Top_Fuel]

...it's under warranty, so it's going in in a couple of weeks time. I guess they'll do a quick diagnosis before they actually rip it apart; but based on other Mirages having the same issue, it sounded like it was a given that's the problem and that's what they'll do.

Be sure to report back after you have it done. If a new matrix (heater core) fixes your car, I will be making an appointment to have mine looked at!

I like Eggman's idea of examining the old parts. But like you said...manufacturers often requires the dealer to hold onto replaced parts for audit purposes. But maybe we'll get lucky. It would be interesting to fill your old heater core with hot water and take temps of the various areas of it.

[Fummins]

Off topic a bit, but I've no idea how folks still buy cars in the UK that only come with a 2 year manufacturer warranty, with the third year being at the grace and goodwill of the supplying dealer (eg they wriggle out of everything). There's a few manufacturers that do that still - reliable marques - but even so, Mitsy are reliable and here we are with heater problems! lol

You mean there isn't a longer warranty for power train(engine and transmission)? We have 10 year 160000kms warranty with Mitsubishi in Canada and I'm pretty sure the same goes for the USA.

[Fummins]

If the heater core AND evaporator have to come out of the car to swap the heater core, this job will be a pain in the butt for a DIY repair.

I didn't consider having to pull the evaporator out. It sorta looks like you'd have to pull the heater box assembly out as one piece then open it up to get the heater core/matrix out. It would be a pain if you have ac. I wouldn't recommend average Joe to attempt it if that's the case. Draining the ac can make a mess if you don't have the proper equipment(so I hear)..