Hi! As per title, a/c doesn't work. It was working fine, stone cold and since yesterday it has decided to not activate.

2020 Jan reg Focus MK4 St LineX, 1.0 Ecoboost MHEV 155PS

When I press the AC button I can hear fans blowing faster, but I don't hear the "click" when I presume AC clutch was normally engaging in the last. Instead of cooling, air from vents seems gradually warmer.

I've checked the fuses for climate control inside the internal fuse box and AC clutch fuse in engine bay - all fine.

I've hooked up my laptop with forscan and apart from errors from me pulling fuses, nothing else was there. I've reset dtcs, ran the car and no errors were found. Deeper in options I've ran HVAC reset procedure, HVAC flaps adaptation and ambient temp sensor wipe of stored data, sadly no effect either.

Data logs pic attached. Ac_req value changes between Yes and No when I press the ac button, but the ACCLT_ALW and ACC_CMD do not change from No and Off.

Sidenote, I had alert from my ford app about low battery voltage due to my doing just a few short trips recently, so took the car on a longer trip with a hope that this might be related, not change.

Any help and tips will be greatly appreciated!

Periodically, our 71 Fiesta air con would not come on. Along with the passengers side keyless entry. All to do with low state of charge. Even after battery was replaced by Ford dealer under warranty. Air con often wouldn't come back on, even after a run or being on charge. So I always did a quick BMS reset. 5 main beam flashes and 3 brake pedal presses. Then all worked fine.... until the next time.

But, recently the air con has not been working, and no amount of charging or BMS resets would make it work again. I run Forscan, and no errors at all. In desperation, I disconnected the battery for a couple of minutes. Reconnected and all working again. I've now had to do that 3 times in as many weeks

So it might be worth a try disconnecting the battery

@Apollogary Thanks mate! BMS module reset worked like a charm. 

Only reset BMS is you have fitted a new, fully charged battery.

Tricking the system by resetting BMS just causes more problems down the line.

Your car is five years old now.

Fit a new, non Ford, fully charged, higher capacity battery, then reset BMS and you'll never have any more problems.

Increase max charge rate to 95% too

12 hours ago, DaveT70 said:

Only reset BMS is you have fitted a new, fully charged battery.

Tricking the system by resetting BMS just causes more problems down the line.

Your car is five years old now.

Fit a new, non Ford, fully charged, higher capacity battery, then reset BMS and you'll never have any more problems.

Increase max charge rate to 95% too

Yes I agree, but from experience, a BMS reset normally gives me 2 to 3 months without any problems. And if a full charge won't get the air con or passenger keyless working again, what other option is there?

I would like to fit a bigger capacity battery. Bigger physically I don't think is possible. Is there one  you would suggest? I've currently got it set at 90% charge

2 hours ago, Apollogary said:

I would like to fit a bigger capacity battery

Fit the Yuasa YBX7100

https://cdn.tayna.com/datasheets/YBX7100_DATASHEET.pdf

Thank you. This is for our Fiesta

The Yuasa fitment guide says it doesn't fit Fiesta. Should I ignore that?

2 hours ago, Apollogary said:

The Yuasa fitment guide says it doesn't fit Fiesta. Should I ignore that

Yes.

It says it doesn't fit because it is for the Fiesta 1.5 diesel.

Your battery tray is the same size and the battery will just drop straight in.

2 hours ago, unofix said:

Yes.

It says it doesn't fit because it is for the Fiesta 1.5 diesel.

Your battery tray is the same size and the battery will just drop straight in.

Brilliant. Thanks, I'll get one ordered