2019 2.4 heater fail

[sipaldi]

Hi all, I have a 2019 2.4 and the heater failed this morning, just blowing cold air no matter what setting I try. It was in for service December and when it came back I could hear a slight noise from the heater fan which was not there before. 2 months later, only blowing cold air and I don't hear the noise anymore. Any ideas before I book it in again with a 60 mile round trip to the nearest dealer.

 

[sipaldi]

Nobody had this before? Its a strange one. Checked the coolant, all ok. No heat from either the electric pre heat using the app or running the engine in charge or save mode. Just blows cold air no matter what....

 

[littlescrote]

Plenty of vehicles have had heating problems before, search the forum and you'll plenty of information around why. But most of them are related to the 2.0 engine and sand left in the engine block from the casting process.

There are 2 basic things to check - the electric water pump and the 4 port valve.

 

[sipaldi]

Thanks littlescrote.

I rang the mitsubishi garage (jct600) to book the car in under warranty. I was informed on the phone that the heater failure is not a warranty item! Obviously we are going to have issues. After reading other issues and watching a few videos I am thinking the thermostat has gunged up on the 4 way heater valve port. This may be caused by the service agent using incorrect coolant apparently. I have to wait 3 weeks before they have a slot at my nearest quasi dealer 30 miles away. Its been near freezing the last few days and even with the heated steering wheel and seat its not comfortable.

 

[sipaldi]

So, JCT fixed the heater under warranty after some persuasion back in March 2023. Not sure what they did though.
Guess what, heaters naff again (December 2024).
Seems to heat up ok pre warming with the app, then can be lukewarm and sometimes plain cold when driving no matter how long the engine is running. Getting fed up with it now.

Popped the hood, metal pipe from the 4 way valve INTO the bulk head (after inline filter) and heater matrix hot. Rubber pipe from the heater matrix back into the 4 way valve COLD. Engine running for 20 mins, blowing lukewarm on highest setting.

Is this likely to be the 4 way valve not allowing circulation through the heater matrix or maybe the matrix itself? All garages not taking bookings until mid Jan so going to be cold for a few weeks.

I have read all the other posts but not sure if my issue is the same as any others?

 

[sipaldi]

Just double checked the electric pre heater by sitting in the car. The electric heater is warming the vehicle so can only imagine the thermostat needle is sticky in the 4 way valve. In my understanding once the engine is warm the electric heater shuts off, the thermostat opens up the hot water from the engine and provides the cabin heating.

 

[sipaldi]

Just double checked the electric pre heater by sitting in the car. The electric heater is warming the vehicle so can only imagine the thermostat needle is sticky in the 4 way valve. In my understanding once the engine is warm the electric heater shuts off, the thermostat opens up the hot water from the engine and provides the cabin heating.

I rang the local ish mitsubishi service agent earlier and have managed to book the car in on Monday. I will let you know how I get on. The lady on service reception was very familiar with this issue so fingers crossed.

In the meantime, for those of you struggling with the same issue, check out this link.