Block heater matrix/core? half hot/cold, how to confirm

Hi All

Now posting this is the right place :)

First very post here and coming from New Zealand, in which the K12 Micra is known as a Nissan March and i need your help.

I have a 2003 Nissan March 1.4 AT 5DR (JDM version) and problem is that the heater does not produce any heat. Fan blows fine and AC also works just no heat at all out of any of the vents. The car has the digital climate control and it appears to adjust the fan speed automatically when i adjust the temp setting up and down so seems like the temp sensor is working.

I have unplugged the bottom servo and have attempted to adjust the heater vane but this seems to make no difference, i have not removed the servo to see if it snapped like the pics Vicki posted here.

The both of the heater pumps are very hot but the rest of the heat matrix that i can touch is super cold, does this mean the matrix/core is blocked?

See pic.
I have no signs of a leak as checked for:
  • wet carpet
  • fogging car
  • wet smell from inside
But when I turn the engine on, i get a water gargling sound for a few seconds and then stops. Can maybe post video if need be.

Air in the system?

I plan to have a good look this weekend.
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When pulling the front apart i noticed that the spring and clip were loose (lying on the floor) and not connected so it seems the car has been apart before.
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Hi Mika/Descent

I cant smell any radiator fluid in the engine bay and the radiator reservoir is filled up to the max lin, about 5mm over.

I've checked the radiator itself and it filled up too, the fluid looks light brownish/watery and has gold flecks in it (can post pic if needed), normally its green in my previous cars. It's a new car as I've only had it 6 weeks and only now needed to use the heater because its now getting cold where I live. Driving like an oddball with gloves, jacket and a beanie.

I've checked the heater pipes going through the firewall and the inlet pipe is firmer than the return pipe, is this normal.

The inlet pipe feels a little fuller, and I've tried for a few minutes pumping both pipes to move the fluid through the heater core when the motors not running and the engine is cold, working on the assumption i can loosen up a blockage if there is one?

The heater matrix is still showing as only hot my the pipes connecting to it. It's too hot to touch by the inlet/return pipes but further down its still ice cold.
If it is blocked, whats the best way to clear it?

Was thinking a reverse flush with a garden hose? Water in the return pipe and out the inlet pipe (top left pipe).

I think I can get the garden hose to fit over the pipes, might have to soak the ends in boiling water to soften them up first.

I've has a look at my local automotive shop (supercheap auto nz) and most radiator products are for fixing leaks not flushing heater cores separately.
Here in the Land of the Finns, also known as Finland!
Automotive stores have radiator cleaners, you put stuff to radiator, run it for a while and rinse it with plenty of water.
You should have similar products in New Zealand...? :unsure:
Yes they do, didn't think it through as was thinking there was a separate cleaner just for heater matrix/cores but this doesn't make sense.

Will attempt to flush the entire cooling system.
Here in a Land of the Finns my friend has cube z11 and exactly same problem. I know this is old post but like we say in Finland "koitetaan tikulla jäätä" poking the ice with the stick. Did the problem ever get figured out? Cube z11 is basically the same as micra k12
Problem solved. For future to someone with cold radiator, here is little tip. If you have broken linkage:
The broken linkage spring is going up to the "heating matrix/heating core" valve, which is controlling the hot water flow inside the radiator. (No one hasn't spoken about this valve in any of these kind of forums where I have looked.) So this valve is locating at the passenger side near firewall where the heating matrix pipes are going to engine side. If you have this valve closed, it doesen't matter if the broken linkage which controls "flip flop flap" "cold/warm" cabin air is open or closed. It will blow cold air. Sorry for my bad english, greeting from Finland and below I hope these 2 pics is coming through, which shows this broken linkage and famous radiator valve with a small spring where the linkage other end should go. (These are form nissan cube z11 1.4l cr14de year 2005)


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