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Heater Issue


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So I had some heater issues with my GT last year (Air would only come out of top vents for face) which I ended up fixing.

While I had the dash out etc, I decided to re-core my heater matrix as my heat was never the best.

I built everything back up, bled the system as normal - around 4 times now - but I cannot for the life of me get my heaters red hot.
So far I have flushed the system again numerous times, replaced the thermostat and jacked the front of the car up and bleed the system, but still no luck....the heat is just luke warm.

Could an air lock be the cause of this or is there anything else I should look into? Car runs fine with no overheating issues etc. But this time of year in the UK, it would be nice to have some proper heat.

One mechanic said that my matrix may have been re-cored wrong, but I'm unsure how that would be possible?

The car runs a dual core aluminium civic rad also


Thanks for any input.

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I can only think to check the thermostat is functional and not stuck open.

It's a normal opening temperature thermo and not a low temp aftermarket item.

The thermostats have a jiggle pin on them so when the thermo is installed it needs to be the correct orientation or it is difficult to bleed the air bubbles out.

 I read a helpful topic on this forum about bleeding the system: and basically, engine cold and off, heater to hot setting, with the rad filled and the overflow bottle connected and filled to the full mark. Remove the rad cap and push your palm down on the rad filler neck to seal the top. Then squeeze and release the upper and lower radiator hoses to "pump" the coolant round the system. Squeezing pushes the coolant around and the air out into the overflow bottle (bubbling occurs) and when you release the hose it draws in coolant from the bottle to replace the air. Repeated until there was no bubbling. Rad cap off, started engine, ran up to temp. fan cuts in and out, bottom hose hot, engine off, rad cap on, leave to cool. The system should refill with coolant from the overflow if necessary.

Hope it helps.

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Thanks a lot for this Claymore. You learn something new everyday on here.

I thought the thermostat could only fit one way....I didn't know that it had to be fitted with the correct orientation.

I'll drop the coolant, flush the system, check the stat orientation and try the above bleed procedure you mentioned.

A few members on the FB group said that the issue could be that my civic dual core ali rad is cooling the car down too much (which is never a bad thing I guess)..and I should try wrapping it with cardboard or tin  foil (1/3 the rad) to see if that makes a difference?

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14 hours ago, Djaniero said:

Thanks a lot for this Claymore. You learn something new everyday on here.

I thought the thermostat could only fit one way....I didn't know that it had to be fitted with the correct orientation.

I'll drop the coolant, flush the system, check the stat orientation and try the above bleed procedure you mentioned.

A few members on the FB group said that the issue could be that my civic dual core ali rad is cooling the car down too much (which is never a bad thing I guess)..and I should try wrapping it with cardboard or tin  foil (1/3 the rad) to see if that makes a difference?

The thermostat can only fit in the housing one way but you need to turn it so the jiggle pin is in the correct place.

I used the 5efe build manual (Edit: it was actually the Haynes manual) and it said to turn the thermostat so the jiggle pin lines up with the square step on the cap:

685599937_20210314_102436(2).thumb.jpg.76dc9f7081969aa97636aab544464fef.jpg

The radiator shouldn't affect it. More efficient radiators can reduce coolant temps more quickly and handle higher loads but the thermo regulates the minimum temp of the coolant. It keeps the coolant at 82 deg C (at cruise) and this heated coolant is sent to the heater matrix from the head side of the thermo housing. If the thermo is broken it will over cool, but a working thermostat will keep the coolant in the engine at a minimum of 82 deg C.

Edited by Claymore
Haynes manual, not 5efe manual
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That makes perfect sense now.

I'll get on this case and see what orientation mine is currently at. I was watching some YT videos about it yesterday and some said the jiggle pin has to be at 12 oclock. But I trust your judgement/the manual.

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22 minutes ago, Djaniero said:

That makes perfect sense now.

I'll get on this case and see what orientation mine is currently at. I was watching some YT videos about it yesterday and some said the jiggle pin has to be at 12 oclock. But I trust your judgement/the manual.

I've checked and the info came from the 4efe section of the Haynes 92-97 corolla workshop manual:

20211118_111415.thumb.jpg.8345cf4a9753473aa667915a7f69fb70.jpg

I always thought they went at 12 o'clock but not for 4efe apparently.

Might be worth asking Jay on the tgtt forum if he can see it in his Official Toyota manuals for 4efte.

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Quick update,


So I followed the steps above lined the jiggle pin up with the square etc, but I still can’t seem to get anything other the Luke warm air inside the car.

I had her running for about 50mins, fan kicked in twice etc and I kept squeezing the pipes until no more air bubbles were present at the rad cap end.
I compared the thermostat currently fitted to the one I had previously and they are slightly different…jiggle pin design looks a little different.
All coolant pipes were red hot inc matrix pipes in the firewall.
I m thinking could it be something to do with the actual matrix core itself?


Also when I pressed the air recirc button on the dash, the big air vent on the passenger side opens and the heaters get slightly warmer.

Unsure where to go from here tbh.

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17 minutes ago, RoyalDutchie said:

The only thing left is checking if the core gets hot then. Seems the coolant may not be flowing through the complete core. Maybe the air flows past it instead of through the core? Not sure if that is even possible, but at this point should be considering every possibility.

This 👆

The heater core is just a small radiator inside the heater box/cabin. It should get as hot as the coolant is in the engine.

If the core is cold it is either blocked (or the feed pipes are?), incorrectly re-cored (hopefully they got it right!) or air locked.

If the core is hot as the engine coolant then its the heater box flaps not directing the core heat into the cabin correctly.

Start by checking if the core gets hot as Dutchie said.

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The matrix pipes that go through the bulk head were red hot yesterday. So I assumed the core would be the same/similar temps also. However as you both said, coolant may not be flowing into the actual core. Do either of you know how a core could be re-cored incorrectly?

When I replaced the heater core, I also replaced the perished foam inside the actual heater box, but triple checked everything to ensure it was put back properly etc.

The only other point to make - unsure if this is normal - but while the blowers were on full yesterday I could feel ice cold air blowing near the blower resistor ?

 

 

 

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  • 4 weeks later...
On 11/28/2021 at 2:44 PM, Djaniero said:

The matrix pipes that go through the bulk head were red hot yesterday. So I assumed the core would be the same/similar temps also. However as you both said, coolant may not be flowing into the actual core. Do either of you know how a core could be re-cored incorrectly?

When I replaced the heater core, I also replaced the perished foam inside the actual heater box, but triple checked everything to ensure it was put back properly etc.

The only other point to make - unsure if this is normal - but while the blowers were on full yesterday I could feel ice cold air blowing near the blower resistor ?

 

 

 

Only way I would think it could be recored incorrectly is when it is possible to bypass the core itself(Flow follows the red arrow instead of the green ones).

fy0rh1r.png

 

But maybe someone else would be able to help you with other possibilities.

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