Quick answer - almost certainly this is due to a blown fuse, or a heater resistor pack failure. In rarer occasions it could be down to the thermostat or the engine coolant level.
Problems with the heater are common in every car. And of course, when we talk about a heater problem, we’re also likely talking about an A/C problem - so whether it’s the middle of winter or the height of summer, you’ve got a problem if your climate control doesn’t work. In this article, we go through some of the most common reasons that this may happen on your Ford Fiesta and how to fix them.
Problems with the heater blower in the Ford Fiesta are almost always down to one of two things - either a blown fuse or a burnt out heater resistor pack. Fortunately both of these issues are very cheap to repair, and are usually something you can do yourself without the help of a mechanic. Even if your issue is more complex than this, it’s also not something you’ll need to spend a lot of money to fix.
I’ve fixed several Ford Fiesta heater not working issues, and can tell you that your problem is almost certainly addressed somewhere in this article. Read on to find out how to fix this issue yourself.
Blown fuse
This is the first thing you should check when facing any kind of electrical problem in your car. The fuse for the heater blower in the Ford Fiesta is fuse F4 and this is a 30A fuse. Generally a fuse blowing could happen for a number of reasons, but fundamentally a fuse blows when the component it handles draws a stronger current than it is designed to. The fuse is a failsafe to ensure that the wiring doesn’t melt.
The Fiesta has two fuseboxes - one in the glove compartment and one in the engine bay, to the right hand side near the battery. The blower motor fuse is in the engine bay fusebox and not the passenger fusebox. You can find a fusebox diagram in your Haynes manual, or various places online. Make sure you’re replacing the right fuse with one of the same amperage.
Sometimes a fuse can fail and visually look OK - so whether it looks good or not, you should replace this fuse as a first step. They can be had very cheaply on Amazon, so I would recommend replacing it first without doing any more fault-finding. If it doesn’t fix your problem, you can move on to other possibilities.
Don’t renew a fuse more than once. What this means is that if you replace the fuse and it fixes your problem, and then the heater blower fails again, don’t just keep replacing fuses. If this happens it means there’s something wrong with your electrical system and you’ll need to have your car looked at by an auto electrician.
Heater resistor pack broken
If you replace the fuse and your heater blower is still broken, then this is most likely your problem. This is a really common fault not just on the Fiesta but on other cars as well. Typically, the fault people complain of is that the blower motor actually does work, but it only works on full power. It’s either on, or it’s off, and any of the lower settings don’t work at all.
The reason for this is that the heater resistor pack has burnt out. The heater resistor pack controls the current provided to the fan. If you set your heater or air con to low, the resistor adds resistance to the circuit to stop the fan spinning too fast. If you turn the air con up, the resistor reduces the amount of resistance in the circuit to allow the fan to spin faster.
The reason the blower still works on full is because in this case there’s no resistance being added to the circuit - the full amount of current is being provided to the fan and therefore it doesn’t matter whether the resistor pack works or not. This is why your air con or heater will work on full speed, but not any of the lower settings.
The heater resistor pack is located in the lower passenger footwell. You will need to unclip some of the interior trim to get to it, near to the glovebox. It’s a fiddly job but one that can be easily done by anyone even remotely familiar with repairing things in about an hour on your driveway. Heater resistor packs can be had on eBay or Amazon for not much money. You will probably pay about £30 for a genuine part from Ford if you want to go down that route.
Normally I would say go for the genuine part, but to be honest, I did this job not too long ago on my brother’s Fiesta, and we used an eBay knock-off and it still works fine - I borrowed his Fiesta a few weeks ago while my car was in having it’s MOT and the heater blew lovely and warm on all the settings!
Ford Fiesta Heater Resistor Pack
Suitable for the Mk6, Mk7 and Mk8 Fiesta. If your heater blower doesn't work, it's highly likely this is your problem.
Low engine coolant level
This generally only occurs if you’re having problems with the heater, but not the air con. If your air conditioning blows nice and cold, but your heater doesn’t work, this can indicate a problem with the engine coolant.
The way the heater works in the Fiesta is that engine coolant is pumped through the engine and around the heater core, which provides heat to the cabin which is then blown through the vents through the heater fan. However, if the coolant is not warm enough, you won’t get any heat - this is why you don’t get any heat in the cabin until the engine has had time to warm up.
If your coolant level is too low, hot fluid doesn’t make it to the heater core. Therefore, you don’t get any heat in the cabin. In order to mitigate this you should open the bonnet and check your Fiesta’s coolant expansion tank level (you should be doing this regularly anyway) to ensure it’s between the MIN and MAX lines. If it’s any lower than the MIN line, this doesn’t necessarily mean you need a top up - it’s fine for it to be ever so slightly below, but any more and you should add coolant. If you can’t see any coolant in the tank at all, you definitely need a top-up.
This can occur also if you’ve just had a job done on the car that requires the coolant to be changed - such as if you’ve had the water pump changed. If the system hasn’t been bled properly it’s possible that an air lock has been introduced - for which the cooling system will need to be bled up.
We’ve written a full guide on Ford Fiesta engine coolant which you may want to check out if this is your issue.
Bad thermostat
This is pretty rare, and in all honesty you’re going to have other, more worrying problems to deal with if your engine thermostat is broken, but all the same it can cause problems with the heater blower not working. A faulty thermostat may not open up to let the coolant flow through it, and if this is the case, the heater core won’t be getting warm coolant flowing through it and therefore you won’t be getting any heat in the cabin.
If the thermostat is stuck open, it may cause the engine’s temperature to stay low. If the thermostat is the problem, your engine won’t be able to regulate its own temperature and the engine may start to overheat - which you will notice either on the gauge on the dashboard, or you may notice a distinct burning smell. If this does happen, it’s time to pull over and not drive the car until the issue is fixed, in case you cause terminal damage to your engine.
We’ve written a number of articles on the Ford Fiesta, which you should check out if you’re having other problems or thinking of buying this car.
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About the author
Marcus Brown is editor-in-chief of The FatMech and is a mechanic with ten years' experience based in London, UK. Having worked for major dealerships for many years, Marcus now works for a local independent garage and has experience working on nearly every make and model of car. Marcus also has a passion for writing and teaching, which is where the idea for The FatMech came from. In his spare time, Marcus enjoys playing golf, doing home renovations and gardening. He lives just outside London with his wife and son.