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Why Car Air Conditioning Stops Working
Car air conditioning doesn't last forever — and the most common reason it
stops working isn't a broken component. It's simply that the system has lost
refrigerant gas. All A/C systems lose a small amount of gas naturally over
time through micro-permeation in the hoses and seals, even without a specific
leak. Most cars will need a regas every two to three years to maintain full
performance.
However, if the gas loss is rapid or your system is noticeably underperforming,
there's likely a leak — either at a seal, hose joint, condenser, or evaporator.
Topping up a leaking system without finding the source just means you'll be back
in the same position a few weeks later.
How your car's A/C actually works
Refrigerant gas is compressed by a compressor, which turns it into a high-pressure
liquid. That liquid passes through a condenser (in front of the radiator), releases
heat, then flows through an expansion valve where it rapidly expands back into gas —
this expansion absorbs heat from the cabin air, chilling it before it blows through
your vents. The whole loop relies on the right amount of refrigerant being in the
system at the right pressure.
Signs Your Car's Air Con Needs Attention
A/C problems don't always mean the system is completely dead. These are
the most common signs that it's time to book a check or regas:
🌡️
Air from vents not as cold as it used to be
💨
System blowing cool but not cold
❌
No cold air at all — even on max setting
💧
Musty or damp smell from the vents
💦
Water on the footwell carpets
🔊
Unusual noise when A/C is switched on
⚡
A/C compressor not engaging (clutch not clicking)
🌫️
Windscreen taking much longer to demist
💡 Worth knowing
Your A/C system is also used by your car's heating and demisting.
Running it year-round (even in winter on the demist setting) actually
keeps the seals and compressor lubricated — which helps the system last
longer. Leaving it unused for months is one of the most common reasons
seals dry out and start leaking.
R134a vs R1234yf — Which Gas Does Your Car Use?
There are two types of refrigerant gas in use on UK cars today.
Understanding which one your car uses is important — they cannot be
mixed, they use different service equipment, and they have different
port connections (so a technician physically cannot accidentally
put the wrong gas in your car). Here's how they compare:
Older Cars
R134a
Standard on most cars built 1994–2016
- Was the global standard for over 20 years
- Generally cheaper to regas
- High Global Warming Potential (GWP of 1,430)
- Still in use on many cars on UK roads today
- Not compatible with R1234yf systems
Newer Cars
R1234yf
Mandatory on all new EU cars from January 2017
- GWP of less than 1 — 99.9% lower than R134a
- Breaks down in atmosphere within 11 days
- Same cooling performance as R134a
- Gas itself costs more, so regases are pricier
- Different port size — cannot accidentally mix
⚠️ Don't assume by model year alone
Some manufacturers switched to R1234yf before the 2017 EU mandate —
for example, several BMW, Mercedes, Audi, and Jaguar/Land Rover models
moved earlier than 2017. If your car is a 2014–2016 model, check the
sticker under the bonnet near the A/C service port — it will state
which refrigerant is required. When you book with us, we check this
before starting any work.
The Environmental Difference — By the Numbers
| Refrigerant |
In Use Since |
Global Warming Potential |
Atmospheric Life |
UK Cars? |
| R134a |
1994 |
1,430 |
~13 years |
Cars built before 2017 |
| R1234yf |
2011 (early adopters),
2017 (mandatory) |
Less than 1 |
~11 days |
All new cars from Jan 2017 |
✅ We handle both at TGPP Autocare
We carry both R134a and R1234yf refrigerant gases and have dedicated
equipment for each system. Whether you drive a 2005 Ford Focus or a
2024 Peugeot 208, we can carry out your regas on the same day — no
need to hunt around for a garage that stocks both.
Does Running the A/C Really Use More Fuel?
Yes — but probably less than you think, and often less than the alternative.
Running your air conditioning adds load to the engine, which increases fuel
consumption slightly. On the motorway at a steady speed, the impact is modest —
usually around 1–3 mpg in real-world terms.
The more important point is this: at speeds above around 45 mph, running your
air conditioning is typically more fuel-efficient than opening your
windows. Open windows at motorway speeds create aerodynamic drag that costs
more fuel than the A/C. For urban stop-start driving, opening windows is
generally the better option.
💡 Making the most of your A/C
- On a hot day, open the windows briefly first to let built-up heat escape, then switch the A/C on — it'll cool the car down much faster
- Set the A/C to recirculate cabin air rather than drawing in hot outside air — it works more efficiently and cools faster
- The A/C also works as a dehumidifier — using it on the demist setting in winter clears your windscreen faster
- Running it at least once a week in winter keeps seals lubricated and prevents compressor damage from disuse
Why A/C Servicing Is Often Skipped — And Why It Shouldn't Be
Unlike an oil change or MOT, car air conditioning service isn't a legal
requirement and doesn't trigger a reminder light. This means it's one of
the most commonly skipped services — and garages often don't flag it unless
you specifically ask.
The trouble is, a poorly maintained A/C system doesn't just leave you
hot in traffic. A damp or dirty evaporator becomes a breeding ground for
mould and bacteria, which gets circulated straight into the cabin air you're
breathing. A musty smell from your vents when you first switch the A/C on
is the most common sign of this, and it's fixable with an anti-bacterial
clean as part of a service.
- Regas every 2–3 years to maintain performance (or sooner if you notice a drop-off)
- Pollen/cabin filter should be changed annually — a blocked filter reduces airflow significantly
- Anti-bacterial treatment removes mould from the evaporator and eliminates musty smells
- A/C check before summer means you won't find out it's failed on the hottest day of the year
Car Air Con Service & Regas in Stevenage
Same-day service available for both R134a and R1234yf vehicles.
Call ahead or book online and we'll get you sorted — no waiting weeks
for an appointment.
R134a & R1234yf both available
Same-day service
Leak detection & diagnosis
Full system pressure check
Anti-bacterial evaporator clean
Cabin / pollen filter check
12-month guarantee on work
RAC Approved Garage
0% Finance via PaymentAssist
5-star rated on Google
Book Online
📞 01438 232556
Frequently Asked Questions
How do I know if my car uses R134a or R1234yf?
+
The quickest way is to look for a sticker under the bonnet near the A/C
service port — it will state the refrigerant type. As a general rule, if
your car was registered before January 2017 it almost certainly uses
R134a. If it was registered from January 2017 onwards, it will use
R1234yf — though some manufacturers switched even earlier than that.
If you're not sure, just let us know your registration when you book
and we'll confirm before we start.
How long does a car air con regas take?
+
A standard regas typically takes around 45 minutes to an hour. The
process involves recovering any remaining gas from the system, pulling
the system into vacuum to check for leaks, then recharging with the
correct amount of refrigerant to the manufacturer's specification.
Where a leak or fault is found, diagnosis and repair will add to
the time — we'll let you know before any additional work is carried out.
Why is R1234yf more expensive to regas than R134a?
+
The gas itself costs significantly more than R134a. R1234yf is a newer,
environmentally-engineered refrigerant produced by fewer manufacturers,
which keeps the price higher. The service equipment required is also
different (and more expensive) for each gas type. As R1234yf becomes
more widely adopted, prices have been coming down gradually, but it
remains pricier than a standard R134a regas.
My air con works but smells musty — is that a regas problem?
+
Not necessarily. A musty smell is usually caused by mould or bacteria
growing on the evaporator — the part inside the car that gets cold and
damp when the A/C runs. It's very common and nothing to panic about.
An anti-bacterial evaporator clean will sort it out. We include a
system check as part of our A/C service, so we can identify whether
it's a gas issue, a contamination issue, or both.
Can I just top up the gas myself with a DIY kit?
+
DIY top-up cans are widely sold for R134a systems, but we'd recommend
against them for a few reasons. They don't recover old gas first, so
you can end up overcharging the system. They don't check for leaks —
so if gas is escaping, you're just delaying the inevitable. And for
R1234yf systems, there are no true consumer top-up products on the
market. A proper regas at a garage is the right way to do it — and
it's not significantly more expensive than the DIY route once you
account for the kit cost.
Do you offer same-day A/C service?
+
Yes — for most A/C regases and checks, same-day service is available.
We carry both R134a and R1234yf in stock. Book online or call us on
01438 232556 and we'll fit you in as quickly as possible.
How often should car air conditioning be serviced?
+
We recommend a full regas every two to three years as a minimum.
The cabin/pollen filter should ideally be changed every year, and
an anti-bacterial clean every one to two years is a good idea —
especially if you notice any smell from the vents. Don't wait until
the system has completely stopped working; catching it early is
almost always cheaper.
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