Heating issue

[Asac]

2018 PHEV. No heat after battery 12v swap. Correct battery OEM. 400 plus USD. Second dealership. Mitsubishi. Also clean filter, flush, new 12 volt aux pump, new 4 way valve. Vehicle is in air-con mode . 160. Bucks an hour for unfamiliar techs crawling around vehicle. Now they have to contact a platform engineer in Japan to help them. Will keep posted. Car is in Akron Ohio.

 

[Asac]

Tech has been in contact with platform engineer. Mitsubishi themselves are stumped. Will give an update. Now they are leaning towards a heater matrix issue. They say they are chasing air bubbles. Obviously, they have 50 plus coolant lines going everywhere from bumper to bumper.

 

[Stu37]

Try setting max air conditioning for a few minutes and then maximum heat.
The heating now works perfectly

 

[Phev2016]

Ask them to remove the filter near the 4 way valve and confirm it has no build up of 'gel' which would stop/slow flow. There are many threads explaining this common cause (search filter heating) and there is a known method to flush out the system - citric acid I believe. Also, there might be many coolant lines but most mechanics seem able to bleed the system, even if it takes a few attempts and your mechanics should be able to check the heater matrix by flushing it with a hose. Coincidentally there is a thread that was updated today "2019 2.4 heater fail" which has a link to this very good video that explains a lot - this one already had the filter cleaned and they checked the matrix was ok too but they haven't yet fixed it!.

2019 2.4 heater fail​