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Mk2 Heat/fan Problem Or No Problem?!


GeoffJ
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Evening everyone. My first post here so apologies if its located in the wrong section!

I have recently upgraded from an 03 to a 55 (mk2) and already experiencing some problems. Here is the first and the most important one, the rest will follow in time!

Ive only had the car a matter of weeks, but over the last two days ive noticed that (1) the fans have continued to operate for about 2-3 minutes after ive turned the car off (2) the temp guage takes a while to get to between 80-85 degrees ((in my 03 it was almost instantaneous)) and (3) the heater has stopped blowing really hot air and instead only blows warm air.

I will say the heating/fan issues have only just started....and call it coincidence or not it started when I decided to switch and keep the blower direction flow onto the feet area so that I could start drying out the drivers footwell carpet (another issue I will be posting about soon enough!!). for a few days there was no problem and it got very warm there so much so that it was uncomfortable having hot feet all the time, but then a few days in and I noticed the intensity of the heat on my feet was a lot less. Then I noticed one day as I got out of the car that the fan was still on full blast. Since then its been the same everytime i switch off. Tonight i thought i check if changing the direction of the blower would make any difference, but it didn't.

So, does anybody have any ideas what could be going on here? I am hoping i can get this resolved before i get caught short by the cold weather winter will be bringing, so any advice would certainly be appreciated!

Thanks everyone,

Geoff.

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Check the coolant level under the bonnet, with the wet carpet and temperature issues it sounds all the world like the heater matrix has leaked coolant all over your inside.

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Spot on Nathan!! I checked the water and the level was way way way low. I admit I hadn't checked the water level in the 3 weeks since I bought the car, even though the bonnet has been open more times than I can recall. Topped it up and !!!boom!!! I have constant hot air and no sign of the fan on after I've turned her off. everything seems fine and normal now.

So, now that its fixed....can you or anyone else explain what is happening here, why would the fan cut in and why would the heater start blowing cold....I'd like to know the logic of this if its possible!

thanks!

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Bad news for you is something is broken it's a sealed system:mellow:

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Yep I appreciate that, that is now my next mission....to discover the source of the water-loss and ive got a feeling I know where that could be since ive already discovered the water in the drivers footwell.

I just don't understand why the fan would be kicking in after ive turned her off and when its low on water, and why the heater was blowing luke warm. I suppose I need someone to show me how the water/heater systems all work together?

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The heater matrix is a small radiator. So if you have very low or no coolant then it wont get hot hence only lukewarm air. Also the fan could be coming on for yhe same reason to prevent overheating. Hope this helps.

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Oh I see, well partly. So the matrix wont heat and therefore there will be no heat to disperse in the cabin with the blowers. Gotcha.

But the fan coming on to stop overheating of the radiators? ?? if there isn't any water to heat them then I don't understand why the fan(s) would kick in??? or am I missing something here? I just want to eliminate a faulty.....something.....I suppose.

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The fan will come on due to a response from the engine thermostat the thing would be getting very hot and it doesn't know that there is very little coolant so it just assumes that the coolant is hot and tries to cool it, if you bear with me I could draw a very simple diagram on my note of how the system works and upload it.

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Ignore the overflow note that's a lie, take that as a return to the resovoir, there is also a small pipe on the ford system which is like a bleed return to eradicate air in the system.

post-40601-141591975306_thumb.jpg

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OK thanks I think I get it. Altho I thought the thermostat opens up to allow the flow of water around the system and engine to keep it cool...im guessing the stat is therefore not opening up or that's its opening up but with a lack of water to cool the system sufficiently the fans are getting the message to switch on from the rad temp sensor? or is that logic incorrect?! Odd.

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There are electronic temperature sensors that take readings of the current state of affairs, these signals go to the ECU and the ECU will only intervene when the coolant temperature or in your case lack of it means that the pre determined safe maximum is reached lets say 100 degrees, the ECU will then switch the rad fan on until the temperature is safely below the desired temps, the thermostat is a mechanical part and is built to move at a certain temperature, when the engine is started cold the thermostat will stay closed to allow the engine to warm up quicker helping with efficiency and performance, once the thermostats opening temperature is reached it will open the system up and allow a flow through the rad aswell to maintain the operating temperature, on a well running and leak free system the engine fan will very often only come on if parked in traffic or direct sunlight at an engine idle due to the lack of airflow through the radiator, the only other reason for the fan to run would be the use of Air conditioning in which case the fan will run continuously until the AC is turned off. I have excelled myself there. :D

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Lots of ways to explain it but think of it like this youre cooling sytem is like a pressure cooker its a sealed pressurised system when the engines warming up the thermostat doesnt open it instead diverts the coolant directly round the engine allowing quicker warm up time when the engine reaches optimum temp the thermostat opens allowing the coolant through the radiator however if the external temp is low the coolant will get too cool and so the thermostat closes and the process is repeated using the interior fan takes heat from the coolant sytem and therefore the engine.if the coolant is too low one you dont get enough pressure in the system so the coolant actually boils off second as theres too little coolant theres not enough heat in the system any heat there is the heater is stealing so luke warm air when you switch the engine off as the water pump isnt running the engine actually gets hotter hence why the fan comes on to cool the engine which is monitored by the ecu.

Hopefully youre matrix isnt leaking causing the loss of coolant

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OK thats brilliant folks and now i understand the process a little better....its time for me to find the leak. Im going to monitor the water level over the coming weeks to make sure there is a water loss from the system...if there isnt then i guiess i can determin that the water ingress in the footwell comes from another source - ive heard windsheilds and bulkhead seals are a favourite!

Thanks for all your assistance, i will update this post as and when i discover things.....:-)

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The yellow cap on the expansion Bottle is a favourite for coolant loss that's unexplained, also watch for excessive steam from the exhaust to rule out the head gasket.

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That yellow cap is a b*******d to get off i will say, so i doubt my issue could be that!

But now im a tadd concerned by the whole head-gasket scenario! Wont i see creamy gung in the oil header if thats gone?

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Well yes but a head gasket can go in many different ways. Sometimes gunk on the oil cap could just mean condensation from blocked breathers.

Sent from my iPhone 6 using Ford OC

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Maybe not always, It sounds very much like the heater core is out of time.

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Yeah thats what im thinking Nathan. I will check the oil cap tho just to be sure. :unsure:

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well things have progressed in the short time between posts....the heating, or lack-of, and fan on after switch off problem is back tonight. I checked the water bottle and again there was nothing in it. whilst I was there I checked the oil cap and there was no gunge.

this leads me to believe I have a bigger leak than I originally thought :-(

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Soak up the footwell water with a white cloth/kitchen roll. If it goes pink, its coolant from a matrix leak. If its clear its rain water from elsewhere.

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I doubt its the gasket they arent known to be an issue the cap may have a twisted seal ten quid replaces the whole cap and eliminates that it sounds like a matrix which is worse a gaskets easy to get to the matrix isnt easy way to tell taste the water in the footwell youll know instantly if its coolant or plain water you will need to add coolant to the system not just water.if the footwell is tasteless its from a leak if you have aircon possibly the aircon drain hose behind the drivers left hand kick panel

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If this is the matrix; from what I am discovering from the interweb it could be a dash-out job to replace it.

If that's the case then I reckon that could be labour intensive and therefore costly.... :-(

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Yep, matrix changes are very time consuming for such a small and easy part when you finally get to it. I'd honestly rather swap an engine than pull a dash out for a matrix change lol.

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Oh that's just brilliant !!

If it is that (which I strongly suspect it is), anyone have or found a guide or how to?!! ive googled it and nothing. I want to see if its DIYable or not.

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It should be easy to do once you get the dash out of the way that's the real problem here

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