General Heater Blowing cold Air ....Water Pump or thermostat...please help i'm confused

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General Heater Blowing cold Air ....Water Pump or thermostat...please help i'm confused

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Jan 29, 2008
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Ok so heres the deal
I have a 98 Plate Mk1 Punto on an 'S',just been through £300 for MOT Last September,then a new Alternator in Nov,also a new battery in total about just over £500 which i couldnt really afford but anyway the heater just blows very cold air the no1 setting doesnt work at all 2nd and 3rd like i say very cold,,i bought the car off a friend who in turn replaced it with a newer 51 plate punto ,she told me she had the same problem cold air then when the heater is off you smell burning which i can,then my father in law said it could be the thermostat but the car has never run hot since i've had it(almost a year now),i dont know what to do any help would be greatly appreciated , i know this topic has maybe come up before but i just had a quick look and couldnt see anything Thanks for any help in advance...John
 
Hi and welcome to the forum.

There are several potential causes to the cold air, including having been bypassed earlier in its life.

The place I would start is to inspect the condition and operation of the thermostat as that's the easiest one to do (make sure you create a new seal after cleaning the matic surfaces, I used an instant gasket and it's been fine).

The operation can be checked by immersing the thermostat into hot water and watching the mechanical action, of course be careful handling the water and the thermostat when hot!

If it's anything like mine it may take a while to clean out, whilst your at it you may want to have a look inside the cooling chamber that you can now see via the hole the thermostat has created (you can see examples in my gallery, if you want a hand accessing that then ask).

If the inside is obviously badly gunkde up I would go for a full flush of the coolant and replace it with a new mix and some rad flush, then after the time instructed wash it out and fill up again. Mine still had the original coolant in it when I bought it and it had made a horrid mess :( Again, if you want detailed instructions then ask.

If the thermostat and internals look fine then I would move the car to a slight incline, pointing the hose up and attempt to bleed the system which is detailed here (https://www.fiatforum.com/punto-guides/90237-bleeding-cooling-system-mk1-punto.html). There may simply be an airlock in the heater matrix but it's a better bet to check the condition of the system in the order I am describing it in.

If neither of these work then it's time to look at the pump, details of how to changed that are located here (https://www.fiatforum.com/punto-guides/92606-how-change-water-pump.html)


As for the heater setting 1, that is most likely a connector has come loose around the resistor block. I have never had any dealings with this but I gather it is somewhere under the dash on the passenger side or the centre of the console and is usually blue or green but I have no idea what colour they are for FIAT!
 
If it was the thermostat, it would either stick open (heater blow cold and car would never warm up either) or stick closed (car overheat quite quickly). They usually stick open if they go, but you can be unlucky and have them stick closed.

Same thing with the waterpump aswell if it isnt working the car would overheat quickly.

Do you have a temperature guage? or just a high temp warning light? If its the later (just a warning lamp) I would get the thermostat and pump checked over by a garage just to confirm they havent developed a fault as the light will come on very very late, damage likely to be done when it does come on.

Have you checked your coolant levels? If its low its liekly you have air in the system that prevents hot water from the engine getting to the heater matrix and heating the cabin.
 
It could be as simple as low coolant level

Firstly check the level

I'd drop the coolant and flush a good thing to put in with your coolant before dropping is engine flush

pour in run for 20mins and drop the load is clears all the gunk
 
Hi and thanks for the warm...LoL welcome,,,ok hear goes good news first i topped up with coolant and lo and behold its blowing warm air again ,, the no1 position still doesnt work but i can sort that probably , i've just topped it up for now but i'll try and flush it out and bleed it at the weekend, I'll let you know how i go not done it before so it'll be fun hee hee thanks so much for your help i know where to come now take care for now,,,,John
 
Did you just pour new coolant in? I'm stupid when it comes to cars, do you need to bleed the radiator - as per the guides mentioned when you top up coolant or can you just pour the stuff in? Does it matter what you put in? I mean FIAT say somewhere to put Paraflu in but is any bottle of pre-mixed coolant from halfords ok? I'm guessing you can buy it ready made :D

Do you have a temperature guage? or just a high temp warning light? If its the later (just a warning lamp) I would get the thermostat and pump checked over by a garage just to confirm they havent developed a fault as the light will come on very very late, damage likely to be done when it does come on.

I think the above has happened to me though and the damage has been done - see quote..
 
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Did you just pour new coolant in? I'm stupid when it comes to cars, do you need to bleed the radiator - as per the guides mentioned when you top up coolant or can you just pour the stuff in? Does it matter what you put in? I mean FIAT say somewhere to put Paraflu in but is any bottle of pre-mixed coolant from halfords ok? I'm guessing you can buy it ready made :D

You pour the new coolant in and follow the bleeding guide :) (requires gradual topping up whilst bleeding sometimes)

Paraflu is what FIAT put in but any ethylene glycol coolant at a 50:50 mix with distilled water is what you're aiming to put in (or pre-mixed). I used Halfords readymixed to top-up whilst I was waiting for enough time to get to the bottom of the troubles I was having.

I would check the pump and thermostat if you feel you need to but try the topup first :)
 
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