Hi all (newbie here),

Fiat Grande Punto Sporting 16v 2007

I have an issue (like many before me reading the threads here) with not much of any hot air blowing into the cabin.

- Coolant level good
- Fan working on all levels (just blowing cold air)
- Heat indicator on dashboard increases slowly when driving but lately it is often slightly below normal running temp

My suspisions:

- Malfunctioning thermostat (left open to long/much)
- Clogged heater matrix

Now I am not very experienced at all with cars (and to be honest I could not really point out different parts of the engine just by looking at them) but I like to figure things out and try and work on them. Only small things I have done so far is changing ignition coils and normal maintenance so do you guys think it would be possible for me to attempt to change thermostate and flush heater matrix?

I downloaded the eLearn but could not find sections on changing thermostate and how to locate the heater matrix, so I guess my first question is how to locate them (if someone could be kind enough to take picture that would be amazing).

Many thanks

1st update: Thermostat located, looks slightly tricky to get to but should probably manage

On cold engine, set hot air+blower on 1st speed in cabin. Now check with hand water hoses in engine bay. After while you must feel temperature in hoses. Find 2 hoses whose are going from engine to interior, both must be hot too. If not, cabin radiator is clogged. And now - upper hose to main radiator (that big one mounted between front bumper and engine) must be cold - that means that thermostat is still closed. If yes, its ok. And after while, this upper hose will be hot quickly - that means that engine reached operational temperature and thermostat opened - thats ok.
I'll start with checking that upper hose to main radiator, because thermostat is critical component for engine. If this is ok, then you xan check mentioned 2 hoses whose are going to interior radiator...

I had a problem with air locks in my Grande, I seem to think that the Grande and other Fiat’s of that era do not circulate the coolants to the cabin via the thermostat and that the cabin is in the same loop as the engine so as the engine warms up so does the cabin.

Thanks Rado77,

Before I do these tests I have attached some pictures so I know I am feeling the right ones

Pic2 attached: the two hoses leading to the heater core
Pict3 attached: Upper hose to main radiator

Is this correct?

AndyRKett said:

I had a problem with air locks in my Grande.

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May I ask if you solved the air lock problem and how in that case, thanks

Your temp gauge should reach mid range bar (90ish°) after a few miles only and never be below that line while cruising. The behaviour you describbe is EXACTLY the symptom of a bad thermostat !
- remove it, if not already open (which I suspect):
- throw it in a pan full of water
- heat until small bubles appear in the pan's bottom, this IS 80ish°
- continue heating, the thermostat should start opening slowly BEFORE the water start boiling

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

You are right guys. Hoses to interior heater core are on primary circuit and it has nothing to do with thermostat - only in case if thermostat is stuck in opened position - in this case is water going through main radiator and heating-up engine takes very long time, and heater in the cabin isn't heating so quickly as usual.
I tried to explain that method with checking upper hose to cooler without having to remove thermostat. Of course the best method is to remove it as Bernie suggested and check it at home - you'll be definately sure if it's stuck in any position, and if it's working as it should (in that pan with water).

Three possible scenarios:
1, thermostat is bad - replace. If thermostat is good, then
2, can be clogged heater core
3, flap mixing cold/hot air is stuck or cable from dashboard controller to flap is broken

PS: and yes, you identified correct hoses on pictures ;-)

Water (coolant) circulates in the whole engine thanks to the water pump. As the portion of the circuit to the cooler (radiator) is closed by the thermostat (but a very tiny hole), the coolant not being cooled down in the radiator warms up pretty fast and can transfer heat to the cabin (if the heater is not clogged and the flaps/valves are ok).
IF the thermostat is stuck open, the coolant circulate also trhough the radiator so is kept cold way longer than with a working thermostat, so heat in the cabin can take ages to reach a comfy level.
SO the very first thing to do before attempting anything else is to verify/fix that thermostat !
BECAUSE it can be stuck PARTIALLY open and may not FULLY open when requested (traffic jam, etc.) and cause dammage to the engine ...

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Thanks guys for all your help, very much appreciated. I am almost certain the thermostat is faulty so I found a good one (heavily discounted luckily for me) and will fit it as soon as it arrive which will hopefully take the car back to normal running temp.

I do indeed suspect that there is an issue with the heater matrix as well though as it never generate any warm air in the cabin, no matter how long time I drive (even when the running temp is ok).

I felt the hoses leading to the heating matrix just now after a decent drive and they are barely warm to the touch so definitely something going on there.

I will update as soon as I have fitted the new thermostat and then will likely give it a go to flush the whole system (including heating matrix).

Thanks again for your help.

Rado77 said:

3, flap mixing cold/hot air is stuck or cable from dashboard controller to flap is broken

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The flap/cable can be accessed from inside the car (under glove box or the same area on driver side) is that correct?

IMHO it wouldnt be a bad idea to flush the cooling system through,a few times and change the coolant/antifreeze.

nikrox said:

IMHO it wouldnt be a bad idea to flush the cooling system through,a few times and change the coolant/antifreeze.

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That'd be the exact correct time to do it indeed !!

Cheers, Bernie

Bernievarian said:

That'd be the exact correct time to do it indeed !!

Click to expand...

Hi Bernie, do you think this would be an okay order to get things done:

1. Drain radiator > Fill with water > run engine to get thermostat to open (probably already is) and flush
2. Rinse repeat until water drainage from radiator is clear
3. Revers flush heater matrix until clear
4. Replace thermostat
5. Repeat step 1 once more
6. Fill up with new coolant

Also, I guess it would be good to stock up some hose clips before to have once thermostat change is done

Sounds like a good plan, and clips provision is a brilliant idea ! Be carefull with the radiator drain screw: very brittle ! Use a six side eye wrench or socket ...

Cheers, Bernie

I have a problem with a clogged heater core. The bottom hose to the heater core is hot, and the upper hose is ice cold... But my question is how to fix this?

My first thought was to find the two hoses that go to the cabin from the engine bay area, but I couldn't do that. I have LPG installed on the car and the space is tight and too many hoses... can someone help identify the heater hoses? The car is a Grande Punto 1.2

If I remove the two hoses inside the dashboard, I guess all antifreeze will leak out. Also, I don't want to drain all the antifreeze, the temperature outside is very cold, don't feel comfortable doing that on parkin lot and I don't want to deal with airlocks