Fiesta Heater no heat!

[OhGranny]

Hi
The last couple of weeks I am getting very little heat from my heater.
I know it has been cold but when I am motoring along the heater works O.K. but in a queue of traffic or at a standstill it blows almost cold and a couple of times the radiator fan has kicked in even on these freezing mornings.
If I turn the engine off and back on again the radiator fan doesn't run.
The temperature gauge shows normal all the time and I can't see any change from what it was before.
But it is definitely a lot colder that it used to be.

Any ideas what it could be?
G.

 

[Jimmyjaffa]

Hi, you have checked the coolant level as if its low it will only get into the heater matrix when you rev the engine, just a thought.

 

[Jimmyjaffa]

What vehicle is it?

 

[cjard]

As per the topic title, it is a Ford fiesta


Car heater systems are simple devices. Water circulates round a short circuit of just the heater system when the engine is cold. When the temperature of the engine rises, a thermostat valve opens and uses the rad at the front of the car to disperse heat. THis allows the heater in the car to start working quickly for your comfort and allows the engine to reach operating temp quickly for economy reasons.

In the heater box of the car, cold air is drawn through an opening under the windscreen. A flap directs none, some or all of the air through a radiator and out of the vents in the car.

Thus there are 3 reasons why a heater might blow cold:
1 There is no water in the heater radiator
2 There is water in the rad, but it is cold
3 There is hot water in the rad, but the flap is stuck in the COLD position and air is bypassing the rad

Causes for each of these are are:
1 The coolant is low or was refilled after being low and the heater is airlocked
--> fill the coolant and ensure the heater is bled properly

2 The pipes leading to the rad are (partly) blocked and the hot water flow is low or the car's thermostat has failed and is stuck in the open position meaning that the water flowing into the heater isn't very hot at all
--> ensure the pipes are free of gunk (if the water in the header tank is brown/rusty it is likely, if it is green/blue/yellow/not rusty then it is less likely) and that the car thermostat is opening at the correct temperature.
Thermostats are designed to fail open rather than fail closed as this avoids engine damage

3 The knob on the fascia is not correctly cauing the air-divert flap to move. Usually the flap will be stuck in one position and excess force on the fascia knob has broken some part of the link from knob to flap
--> Investigate and fix the mechanical failure of the knob/flap link

 

[ZETEC153]

hi

this is a really common problem on fiestas. its the solenoid valve situated on the bulk head. normally you can hear a knocking sound coming froim behind the dash when the dial is on hot.

if you open the bonnet and look into the compartment behind the carpet on the bulkhead, you should see 2 pipes going into the valve from the cooolant system in the engine.

the pipes connect to the coolant valve.

go to fords or amotor factors and order a new valve - about 30 quid.

if you know one end of a spanner from the other then it should take an hour tops to strip out the old one and fit the new one. the coolant system does not need to be drained but be prepared for some loss of fluid.

hope this helps

george

 

[OhGranny]

Thanks a lot everyone.
Gives me something to work on.
G.

 

[OhGranny]

Feeling like a bit of a numpty now Skippster.
Checked the coolant level and it has taken a full litre bottle and as much water to top it up.
Car has only recently passed MOT. never had to top it up before.
Where can it have gone?!!!
I have a large sheet of cardboard under the engine now to try and spot any leaks - good news is the heater is working better.
G.

 

[cjard]

Car has only recently passed MOT

Not an item that comes under the MOT, I'm afraid

never had to top it up before.

Er, this is a bit of a nonsensical statement. It would be more logical if you'd said "never had to top it up and I check every week that the coolant level is normally exactly as it should be"

Right now it seems it's been a while since you checked it so if it's been losing water very slowly via some joint or failing pressure cap for the past X years and you never topped it up, then it could be the reason why it's low!

Where can it have gone?!!!

Either into the oil, or into the environment. A quick look a tthe dipstick or the underside of the oil filler cap should tell you whether you have a busted head gasket worry or not

I have a large sheet of cardboard under the engine now to try and spot any leaks - good news is the heater is working better.
G.

I'd watch the level before bothering with sheets of cardboard. If it doesnt drop drastically over the next few weeks then you have a very slow leak on your hands

 

[OhGranny]

Hi Cjard
No drips on the cardboard so no visible leak.
As for the MOT what I mean is I did check the level before it went in and I'm sure they must have (do they?) and that was only a few weeks ago.
Dipstick looks fine oil filler cap no white gunge.
A mate has given me a bottle 125ml Holst radweld - should I use it?

Thanks
G.

 

[cjard]

Hi Cjard
No drips on the cardboard so no visible leak.

Check the footwells for leaks from the heater. Remember that carpet can be quite thick so it can soak up quite a lot of water underneath before it looks wet

As for the MOT what I mean is I did check the level before it went in

Using a litre in a couple of weeks is a little excessive, but might not be noticeable on your cardboard given that "a dripping tap can use as much as a litre an hour"

and I'm sure they must have (do they?)

Nope!

A mate has given me a bottle 125ml Holst radweld - should I use it?

Not at this time. It may be a failed pressure cap causing loss by evaporation or soemthing else that radweld will not fix. You can also have the system pressure tested at some garages; it is pressurised to normal running pressure and then leaks are looked for. Alternately, you could just run the engine at idle and watch closely..

 

[Burnerman]

If you can't see any crusty deposits around the hoses or radiator core - indicating coolant leaks, consider looking around the water pump area for leaks in this region. If you suspect the heater matrix, often there will be a funny smell inside the car, with the heater full on. Cheers John

 

[OhGranny]

Hi Everyone
This problem has occured again. The coolant level has not needed topping up since I first started this topic in January.
I checked the level about a week ago and it was fine.
Yesterday I stopped after a journey of about 5 miles and I could smell the engine from outside the car and I had to put in over a litre of coolant again.
No visible leaks and oil looks clean.
Anyway I have contacted the Ford dealer who unnerved me by saying it won't be easy if there is no leak to see !!
He says he can put it on a leak tester but will have to charge me.
Anyone any experience of these testers and the likelyhood of him finding something or charging me for finding nothing?
Ta.
G.

 

[^neo^]

usually they put a dye in the system, then pump it up to pressure so you can see where it leaks from.
If the level drop and nothing comes out, then it'll be going into the engine somewhere which would suggest head gasket

 

[OhGranny]

Hi All
Took the car to a Ford dealer (big mistake!). Thought they may have the best gear to diagonose.
Anyway they pressurised the system said they found leak in expansion tank and fitted a new one.
When I got the car back yesterday the coolant was full of rusty scum and frothing up in the tank and looked really filthy.
I phoned him up, said it didn't look right he said I had put radweld in (not I but maybe previous owner) and it had taken 3 attempts to flush and what I could see was the residue but he had put 3 ltrs of fresh coolant in.
Anyway last evening on the way home the fan kicked in and the temperature shot up. I realeased the pressure slowly and I could see it boiling in the expansion tank.
Seems like the thermostat is either blocked or shut. Don't think it is a sensor or the fan wouldn't have kicked in. I have had this car a few years and it is very rare the fan kicks in. Something has changed and it is worse now than it was when it went in.
BTW where is the thermostat on the Ford Fiesta 1.3 Zetec 8 valve engine? 52 plate.
Ta.

 

[^neo^]

Not sure about the zetec, but most of them are on the top of the head on fiestas.
If not, it'll be in the radiator hose at a guess