The origin of the problem.

I can tell if an Outlander PHEV has a problem with the heating system. It starts to lose the heat at about 40-50K miles because the antifreeze coolant starts to crystallise, block the filter, brake the bypass valve, kill the electric water pump, block the PTC (high voltage heater unit) heater and burn out the heater unit because without the coolant circulation it’s going to overheat. If your vehicle is without PTC heater click here: Mitsubishi Outlander PHEV heating problem without PTC heater and coolant filter.

How to check out

The first step if you can, advised is to check the MUT Diagnostic machine for the fault code and run the test for PTC heater. However, if you don’t own a MUT Diagnostic machine there are other solutions instead such as, If you manage to find any fault codes it means it’s the electric water pumps fault or any PTC heaters fault code and if so you need to do more tests. 

When you test the PTC heater with a diagnostic machine, it will fail and you will need to do more tests on it. Sometimes it will come up with a warning light on the dash (EV SYSTEM SERVICE REQUIRED). If you have proper heat in the air went about 60 Celsius when the petrol engine running and in the electric mode /the petrol engine does not run/starts to drop down rapidly is looks bypass valve fault but first, let’s go to do the sort out the cleaning job.

High voltage can kill you, so do not remove or dismantle PTC heater and orange cable high voltage component let to do the proper qualified technician.

The second step checks the filter 90% time there is the problem blocked with crap, looks like sand and gale, the same as in the picture.

 How it sort out takes a little time and saves money.

Number 8 filter location

Always see or check the number on the picture easy to follow and don’t remove the radiator cap yet. Make sure the car is cold and turn it off.

-Remove the top pipe from the heater core

-Bottom matrix pipe after the bend /rubber pipe about 10cm/ there is the filter inside the rubber pipe remove the top clip and slightly pull out the aluminium pipe from the rubber pipe carefully because the filter can fall out sometimes and hard to find on the under shield, pull out the filter but check what way without damage, and clean out, personally I’m using little brush and brake cleaner.

-Now we have to flush out the system looks crazy but it works, so grab the garden hose and connect it to the top matrix rubber pipe securely and let the water flow for 2-3 minutes with a fully open tap, you can see clean water flow from the pipe where it was the filter is ok now, next remove the garden hose and connect to heater core top pipe and flush out, when you see clean water flow out from bottom matrix pipe is ok.

-We can put back the filter /check the way/ and connect the pipe /where is the filter/ together, again connect the garden hose to the top matrix rubber pipe and let the water flow out from the matrix for 1 minute when the water clears close it and remove filter again to check just in case if clean we are happy if not start to flush out again.

-We are finally starting to bleed the system, put back the filter and connect the pipe back don’t forget the clip, connect the garden hose to the top matrix rubber pipe and open the tap when you see air free flow from the top matrix pipe connect together to try to quickly don’t put back the clip, now you can remove the radiator cap and start to fill up with antifreeze during time pull down slightly the matrix top rubber pipe not fully just a little bit let the coolant leak out but keep top up the radiator may is 2 people recommend when you see the coolant colour push the pipe on and fit the clip on.

-Start the car /make sure it is in the ready mode/ push the charge mode and put the heat temp to a max of about 4-5 minutes you can feel warm air in the air went let it run 15 minutes and take it to road test with normal driving mode minimum 20 minutes if keep hold worm the job was successful.

If start losing the heat on the road test press the charge button and start the heat again if this happens the bypass valve fault location is top of on the trans axle just follow the pipe and easy to found need to replace when you replace the bypass valve start to follow the bleed process.

When work on the right way the next day check the coolant level and coolant strength.  I recommend cleaning the filter every third service and thus we can reduce further damage.

Coolant capacity Dia Queen long Life Coolant Premium or Equivalent Similar high-quality ethylene glycol based non-silicate, non-amine, non-nitrate and non-borate coolant with long-life hybrid organic acid technology full capacity 7.5 litres.


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