Air Con always on full, battery issue?

[Boarr]

Hi all, I have this peculiar issue with my 2010 MK4 Mondeo Titanium.

 

I noticed it first when I hadn't driven the car for about a week, as it's lockdown thanks to Corona. Sometimes after it's not been run for a while it will be a little slow to start like it hasn't fully got enough power to crank, but it starts every time. However, on this occasion after it started, the air conditioning unit just stayed on full blast and the buttons to actually control it weren't working at all. No matter what I hit it'd stay on full, and if I pressed the fan speed down button it'd go down but back up instantly after I stopped pressing it.

 

I used the voice commands to turn it down and off but again, it'd just go all the way back up instantly after. I drove it like that to work and once I had driven it for a while and turned the car off and back on again, it was perfectly fine. Coming out of work the car had zero issues starting and again, air con was fine. It seems like if the battery gets a little drop in power then the air con will get stuck on until it's charged again.

 

I took the car to a garage to test the battery because I'm convinced it's that, but he said the battery voltage is fine. If I'm using the onboard testing facility I can see the battery is hovering around 11.7 - 12.2v and up to 14 when the car is running, but it drops down to like 7-8v during cranking. (Expected?). I went out today and turned the ignition on and low and behold, the aircon was stuck on. I used onboard facility to check the voltage of battery and reading at 11.6 - 11.7v. Is this a battery issue?

 

I'm at a loss at what this issue could be, and while it's not the most annoying thing in the world, I'm worried there is an electrical fault that could loom its ugly head in the future!

[nicam49]

Have you got yourself a multimeter? They're £10ish so well worth having. Don't rely on the on board battery test...measure the battery on the terminals. Anything under 12.6v is low... but if the garage tested the battery, then they would have measured it at the terminals.. And they said it was OK.... 🤔                                How old is the battery? If its >5 years old then you're running on borrowed time anyway. I'd budget for a replacement if it is that old esp. with winter looming. My instinct, being old school is to recommend putting it on charge, but most people these days don't own a charger, whereas it used to be a must to own one. 

[Boarr]

On 11/11/2020 at 5:47 PM, nicam49 said:

Have you got yourself a multimeter? They're £10ish so well worth having. Don't rely on the on board battery test...measure the battery on the terminals. Anything under 12.6v is low... but if the garage tested the battery, then they would have measured it at the terminals.. And they said it was OK.... 🤔                                How old is the battery? If its >5 years old then you're running on borrowed time anyway. I'd budget for a replacement if it is that old esp. with winter looming. My instinct, being old school is to recommend putting it on charge, but most people these days don't own a charger, whereas it used to be a must to own one. 

Thanks for your reply! I'm going to get a multimeter ASAP, and as for the test, while I did get it tested, it was also tested by driving from my house to the garage area which is a 10+ mile journey at 80KM/H, so I suspect it may have not been the most accurate reading.

I can't say the exact date on the battery as I bought the car a year ago, but it's probably a really good idea to just replace it anyway. With a multimeter, I should be getting 12.6v off the terminals~?

[nicam49]

Fully charged it should read 12.6v.  This time of year (Nov-March) I always give my battery a helping hand with a 'maintenance charge', weekly if I remember. Reason being a flattish battery will get hammered by freezing cold nights, and short journeys with lights and heated screens etc on don't really charge the battery enough. 

[Eric Bloodaxe]

 

On 11/11/2020 at 5:47 PM, nicam49 said:

but most people these days don't own a charger, whereas it used to be a must to own one. 

My old charger was donkeys years old so I thought it was time for an update. A smart charger such as Ctek can be had from the usual online sources for £70 or so. I got one during lockdown and have got into the habit of regularly checking the battery voltage with a multimeter and giving it a top up when required. 

[nicam49]

Eric, mine's a Halfords one with an amp meter on the front. I must have bought it  in old money! It's got a 6volt and a 12volt setting and a trickle charge setting. I've had to replace broken wires over the years, but it's still in use.  

[Eric Bloodaxe]

51 minutes ago, nicam49 said:

Eric, mine's a Halfords one with an amp meter on the front. I must have bought it  in old money! 

Lol, I think I had the same one! I was advised not to use it on a current ( no pun intended😃) car with a "smart" charging system, though, so went for a new one which seems pretty good.

[Boarr]

On 11/13/2020 at 5:03 PM, nicam49 said:

Fully charged it should read 12.6v.  This time of year (Nov-March) I always give my battery a helping hand with a 'maintenance charge', weekly if I remember. Reason being a flattish battery will get hammered by freezing cold nights, and short journeys with lights and heated screens etc on don't really charge the battery enough. 

Hi, and thanks for your previous response. I have some unfortunate news to update with. My battery wasn't showing too good, and so I got a new battery as a good maintenance anyway as it's winter, but the issue regarding the air conditioning is still there even with a brand new battery in.

Any ideas on what could be causing this?

[Milkman]

What is your heater/blower working like, does it function on all speeds? Not sure if it could be your issue but if the resistor unit for the heater/blower is gone duff you'll only get full whack in the highest switch/knob position.

[Boarr]

On 11/13/2020 at 5:03 PM, nicam49 said:

Fully charged it should read 12.6v.  This time of year (Nov-March) I always give my battery a helping hand with a 'maintenance charge', weekly if I remember. Reason being a flattish battery will get hammered by freezing cold nights, and short journeys with lights and heated screens etc on don't really charge the battery enough. 

Hi, using my multimeter I tested the new battery after a night of sitting in the freezing cold and it's reading a steady 12.4v, so the new battery is certainly good and it's not being flattened by anything.

3 hours ago, Milkman said:

What is your heater/blower working like, does it function on all speeds? Not sure if it could be your issue but if the resistor unit for the heater/blower is gone duff you'll only get full whack in the highest switch/knob position.

When I start the car it's stuck on full whack, I can adjust the temperature using the dial knobs but I can't change the position of where the air is blowing. I can use Convers+ to put it onto demisting mode or auto mode, but on auto mode it'll go back to full fan speed shortly after. If I use the buttons to drop the fan speed down, it'll just go back up right after like the fan speed up button is stuck in.

Hitting the off button does nothing, however sometimes it just works normal and other times it won't go off no matter how long I drive for.

I have also noticed another problem, the key fob for my car isn't working anymore. The lock and unlock isn't working and as such I have to lock and unlock manually with the key. I checked the battery of the keyfob using my multimeter and it's reading a solid 3v so the battery is fine, looks like I'm having a very bad electrical issue...

[nicam49]

Sorry to hear you're having a bad time of it, Especially this time of year when all I want to do is hibernate!  Key fob issue: has it ever worked for you? It's easy to put the battery in wrong and its also easy to put the battery in on such a way that the connections aren't bent up enough to make contact with the circuit board. So just check those basics.First Is it the only fob youve got for the car? 

[Boarr]

9 minutes ago, nicam49 said:

Sorry to hear you're having a bad time of it, Especially this time of year when all I want to do is hibernate!  Key fob issue: has it ever worked for you? It's easy to put the battery in wrong and its also easy to put the battery in on such a way that the connections aren't bent up enough to make contact with the circuit board. So just check those basics.First Is it the only fob youve got for the car? 

Yeah, especially when it gets cold! The time you don't want issues!

The key fob has been working perfectly up until yesterday, when it stopped randomly. I checked the battery and it's fine, I do have a spare fob so I will try that a bit later and see if it's the problem but I'm thinking it's something a bit more serious than that unfortunately 😞

 

I was reading online about potential other electrical issues and the topic of water ingress came up, and that if a car is steaming up a lot it's a sign of ingress and well, lets say my car does steam up REALLY badly. So I checked the car over and sure enough, the inside of the boot is wet with the spare tire hole actually holding a small puddle of water.

Seems like water could potentially be my problem, could this be causing all these wild issues and if so, do you think it'd be a big fix?

[nicam49]

These threads might help 

https://talkford.com/community/topic/372914-water-ingress-in-boot/

 

https://talkford.com/community/topic/239806-signs-of-water-in-boot/

[Boarr]

51 minutes ago, nicam49 said:

These threads might help 

https://talkford.com/community/topic/372914-water-ingress-in-boot/

 

https://talkford.com/community/topic/239806-signs-of-water-in-boot/

Thank you for all your responses! I'm going to spend the day tomorrow inspecting and drying out as much as I can.

Do you think that the water ingress could be the issue with the electrics? I'm assuming that's where my issue comes from and I don't think I could be far off!