Low Heat Output - New Heater Core Denied

[Top_Fuel]

EDIT - If you aren't familiar with the heater core issues in 2014-2015 Mirages, see the PDF attached to the bottom of this post. This is an explanation/summary of the issue complete with pictures and diagrams.


Grab a beverage. This is a long story.

My 2015 Mirage has a borderline case of low heat output. I first realized it over a year ago after Doax posted this thread about the issue in his 2014.

If you haven’t been paying attention, this problem involves a restriction inside the OEM heater core resulting in a lack of heat output that’s only obvious when it’s really cold outside. One of the first signs people notice is that the driver’s side instrument panel vent/floor/defroster output is hot/warm while the passenger side is warm/cool. If you never feel the heat output on the passenger side, you may have no idea your car may have the problem until it's so bad the driver’s side doesn’t put out much heat. By the time you realize this you might be out of warranty! Did I mention that this repair probably costs about $1,000 at the dealer?

So back to the story…

Compared to Doax, my car has a mild case of the problem. When it’s 20F outside, I get 145 degrees from the driver’s side and maybe 120 from the passenger side. That’s good enough to keep the car comfortable 99% of the winter. It was a -4 today on my way to work, and the passenger side output barely reached 105, while the driver side crept up slowly to 130. On a day like today, the heat output is not adequate on the passenger side.

My warranty was literally 200 miles away from running out, so I took my car in for this complaint last week even though it was in the 30s outside (the colder it is, the easier it is to see the problem). I had a 1-page detail sheet I gave to the service advisor with specific instructions on how to duplicate the issue. It had pictures and everything. Even a service advisor couldn’t mess this up, right? I also asked them to call the Tech Line if they had never seen this condition in a Mirage.

I get a call later that afternoon from the dealer and sure enough…they can’t duplicate the temperatures I have observed multiple times during my own testing. Oh boy…here we go. It turns out they just let the car idle in their shop…where it’s 70 degrees. Then they just drove it around the block and said all the vents were 120. I knew from that low number the car wasn’t even warmed up. So I told them to take it for a 30 minute drive and try again the next day.

The next day comes and I get the same response from the dealer. All vents are now 140 on a 30 minute test drive when the outside temp is 30F (my passenger side vent couldn't reach 140 if you set the car on fire ). Oh…and they said the Tech Line says that “Some temperature variation from the vents is characteristic of the Mirage.” So at this point, they don’t see a problem and the Tech Line says it’s probably normal. I can pick the car up now and pay their $120 diagnostic fee. I told them to keep the car while I called Mitsubishi Customer Support and voice my concern.

I called the 1-800 number and explained what is going on. The person on the phone (just a normal Customer Service Rep) opened a case for me and assigned an advisor to my case. The advisor calls me the next day (from California) and we have a brief 10 minute conversation about the issue. I gave him a lot of details but didn’t make any demands. I tell him that I can live with the condition as it is now, but I need some assurance that I won’t have to deal with this if gets worse by next winter.

So he calls the Tech Line and then the dealership and gets their story. He calls me back within an hour. We have another pleasant 10 minute conversation. He creates some internal Mitsubishi case number and gives it to me, and then assures me that because I have brought the issue to their attention within my warranty period, I will be covered if the condition worsens. All of the details are linked with the case number.

Honestly, that’s all I wanted in the first place. I wasn’t looking forward to this dealer doing a heater core in my car. They have not done a heater core replacement in a Mirage yet…so mine would be the first! So I’m happy, and I think they treated me better because I didn’t call them demanding that new parts be thrown at my car. I think they know there’s a problem, but they aren’t throwing heater cores into cars until the problem is so bad that it’s even obvious to a service advisor.

One interesting thing the service department did that they didn’t tell me about (the Mitsubishi Advisor told me this). The Tech Line told them to try this same vent temperature test on another Mirage. Apparently they had a 2015 in the shop or on the used car lot. They tested it and said it has a 20+ degree variation from right to left and output temps close to my car. The Mitsubishi Customer Advisor asked me what I thought about that. I said…I’m not shocked at all by that. It just means both cars have the problem! Then I said that replacing the heater core clearly makes the issue go away as documented by Doax…and gave him some more data from the forum. He seemed satisfied at that point that I wasn’t completely crazy. He tells me to pick up the car, and there's no charge.

So the bottom line is that my car is out of warranty…but the coverage on my heater core lives on.

My advice to anyone who lives in a cold climate is to check your vent output temps and keep track of them! Based on my testing this year vs last year, the problem in my car is slowly getting worse. My vent temps are about 10 degrees lower this year than they were last year (all other testing conditions being the same). If they are another 10 degrees lower this time next year, I will have no trouble convincing the service manager that this is not normal for a Mirage.