Ford Fiesta (2000 - 2002) - 01 1.25 Heating only works when engine pushed hard | Technical matters | Back Room Forum

Mon 23 Nov 2009 15:19

01 1.25 Heating only works when engine pushed hard - kennygthatsme

Hi All,

I have a heating problem in my Fiesta Freestyle 1.25i (Y Reg). It started about a year ago when I would have the heat control on cold and all of a sudden hot air would come through. This then gradually got worse until around May this year when I could not get any heat out of it at all. This didn?t really matter as the weather wasn?t cold then so I left it. About 2 months ago my car developed a coolant leak and needed a seal changed underneath the engine (not sure how else that describe it!)

I did some searching about the earlier problem on the Internet and found that it was most likely caused by a faulty heating valve, a common problem in Fiestas like mine. I took it to a garage so that they could fix both problems at once and had it replaced and everything seemed ok for the ride home, lots of hot air, I was happy. However, come the next day I got into the car and turned the heating up and nothing happened for about 30 minutes, then all of a sudden I got lots of hot air through. This seemed to have coincided with me hitting a stretch of dual carriageway and the engine having to work quite a bit harder than usual.

Summing up, since then it is only when I go on fairly long journeys (40 mins or more) or really push the engine hard that any hot air comes through. Even when the engine is at optimum temp and I rev it hard once the hot air will come through then go again if I go back to normal driving, so that suggests it?s definitely only working when the engine gets rather hot.

I thought that it may have picked up some sort of air pocket so I have run the engine from cold to optimum temp with the reservoir cap off but this has made no difference. I even asked the garage to replace the valve to see if I had a faulty one, they did this but it has made no difference.

If anyone can shed some light on this, maybe give me some pointers as to what I need to try next, I would be very grateful. The weather, I feel, is going to get pretty cold soon!

Many many thanks in advance,

Ken

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Mon 23 Nov 2009 16:47

01 1.25 Heating only works when engine pushed hard - bell boy

i would suggest your heater matrix is full of crud
an easy job if car doesnt have aircon

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Mon 23 Nov 2009 22:24

01 1.25 Heating only works when engine pushed hard - piston power

Try a new thermostat there is 2x options go for the winter stat & as bell boy says check matrix a back flush required thats connect a hose pipe to one outlet and flush the crud out through the other both pipes off.

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Mon 23 Nov 2009 22:40

01 1.25 Heating only works when engine pushed hard - kennygthatsme

Thanks to bell boy and bigtee for their suggestions.

Unfortunately, it does have Air Con, does that make it impossible or just a lot more difficult?

I will try this back flushing thing, but bigtee what do you mean by "one outlet and flush the crud out through the other both pipes off"? I'm pretty new to this so I need all the help I can get! Are these the two pipes that flow off of the heater valve and into the Matrix? I should put a hose on one and take the other off so it flows right around the matrix and comes out with (hopefully) all the crud?

Know i'm being stupid but if I break this i'm going to be an ice cube in a few weeks :S

Thanks again people.

Ken

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Tue 24 Nov 2009 11:19

01 1.25 Heating only works when engine pushed hard - piston power

Yes two hoses going to matrix flow and return just like the radiator in your house water goes in one end round the rad comes out the other.

Take both pipes off stick hose pipe up it and flush out or better still stick a length of hose onto outlet and drain into a bucket.

It's not rocket science............

Edited by bigtee on 24/11/2009 at 11:21

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Tue 24 Nov 2009 13:10

01 1.25 Heating only works when engine pushed hard - kennygthatsme

I know it's not 'rocket science' (thanks for that, really nice of you), but as bell boy said if it has Air Con things can be more tricky so i thought i'd check...

Thanks for your help.

Ken

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Tue 24 Nov 2009 14:09

01 1.25 Heating only works when engine pushed hard - bell boy

Do as bigtee says kennygthatsme, its just with air con fitted you cant get the heater matrix out without decompressing the air con system ,or at least it doesnt look like you can easily last time i looked at one as all the pipes go in the same place.
Leave the hose pipe connected for 10 mins but make sure the dipstick is well in so no water enters your engine block

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Mon 8 Nov 2010 09:42

01 1.25 Heating only works when engine pushed hard - kennygthatsme

Hi Bell Boy,

Ok I know it's been nearly a year but I have only just got around to flushing the matrix yesterday! Unfortunately, I still seem to be in the same boat. I get cold air when I don't push the engine and temporary warm air when I do. I thought I might have an air pocket so I ran the engine with the water cap off from cold to hot but this didn't make a difference.

Only thing I can think of is that maybe the crud has got into the water switch (which I had replaced last year).

If you or anyone else has any suggestions it would be great to hear them, can't face another winter dressed like an Eskimo.

Cheers,

Ken

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Mon 8 Nov 2010 16:38

01 1.25 Heating only works when engine pushed hard - over30

It sounds like the 'Heater Control Valve' is faulty, just had this same problem on a Fiesta, changed the valve for a new one, problem solved, heater works just fine now. I did change the thermostat also, thinking that this was to blame.

This is a common fault with Fiesta's and Ka's, they both use the same part, which is prone to failure.

Even new aftermarket valves can fail after a short time!

Edited by over30 on 08/11/2010 at 16:44

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Tue 9 Nov 2010 08:48

01 1.25 Heating only works when engine pushed hard - kennygthatsme

Thanks for this, have just ordered a new valve so will let you know how it goes once i've replaced it. Can't believe the one I have now hasn't even lasted a year! Hope the new one is not another duff one, these things seem to be the most unreliable component ever made!

Thanks again,

Ken

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