12 AC Efficiency Problems TM44 Inspectors Keep Finding in 2025/2026 (And How to Fix Them)

When businesses think about TM44 air-conditioning inspections, they usually imagine a quick tick-box exercise.
But 2025 has changed everything.

With the UK pushing harder on energy efficiency, carbon reduction, and compliance enforcement, TM44 assessors are uncovering more AC performance problems than ever, especially in offices, retail sites, hotels, warehouses, and mixed-use buildings.

And here’s the truth 👇
Most of these issues are avoidable, and fixing them saves businesses serious money.
(We’re talking 10–40% energy savings in some cases.)

In this guide, we break down the 12 most common AC efficiency problems TM44 inspectors are finding in 2025, why they matter, and how you can fix them before your next inspection.

If you want to stay compliant and avoid costly energy waste, this post is your blueprint.

Why AC Efficiency Problems Matter in 2025

Before we dive in, here’s why efficiency issues are such a big deal right now:

• Energy bills are at an all-time high.
• AC often represents 30–60% of a commercial building’s energy use.
• The UK government is increasing TM44 enforcement, especially for buildings over 12kW cooling capacity.
• Businesses with poor efficiency ratings risk higher operating costs and may face non-compliance notices.
• TM44 reports now have stricter quality standards, meaning issues are documented clearly and require action.

If you run an office, shop, restaurant, school, hotel, industrial unit, or warehouse, this matters.

1. Dirty Condenser Coils — The #1 Efficiency Killer

This is the most common issue found in 2025.
Outdoor condenser coils accumulate:

• dust
• pollen
• pollution
• debris
• oil mist (common in restaurant and industrial sites)

Even a 1mm layer of dirt can reduce system efficiency by up to 15%.

Why it matters:

The system must work harder to expel heat, which:

• increases running costs
• reduces cooling output
• shortens system lifespan

Fix:

Schedule coil cleaning twice a year, especially in cities or industrial environments.

2. Blocked or Restricted Airflow

TM44 inspectors constantly find blocked:

• vents
• grills
• filters
• ducting
• fan coil intakes

This is extremely common in offices where furniture is placed in front of AC units, and in warehouses where pallets block air pathways.

Why it matters:

Poor airflow means inefficient cooling and drastically higher energy consumption.

Fix:

Free the airflow paths, relocate obstacles, and maintain filters regularly.

3. Oversized or Undersized Systems

This is a big one, and businesses rarely know it.

Oversized systems short-cycle (turn on/off constantly).
Undersized systems run continuously and never reach set temperature.

Both waste thousands of pounds annually.

Fix:

A TM44 report includes load analysis recommendations.
Consider upgrading units or splitting zones.

For help, see our service page:
👉 https://tm44.uk/tm44-air-conditioning-inspection/

4. Incorrect Refrigerant Levels (Overcharged or Undercharged)

Low refrigerant = low cooling power.
Overcharged refrigerant = compressor stress and early failure.

TM44 inspectors find this constantly because systems were topped up by non-F-gas engineers or developed small leaks.

Fix:

Have an F-Gas certified engineer perform leak tests and adjustments.

Also relevant:
👉 F-Gas Leak Testing & Compliance Checks (https://tm44.uk/services/)

5. Poorly Maintained Filters

Dirty filters reduce airflow, increase system strain, and harm air quality.

Hotels, offices, schools, and gyms are high-risk environments where filters clog quickly.

Fix:

Change filters every 3 months (or monthly in high-use buildings).

6. Inefficient or Outdated Controls & Timers

This is becoming one of the biggest compliance problems in 2025.

TM44 inspectors keep finding:

• AC left running overnight
• incorrect time schedules
• heating and cooling fighting each other
• no zone control
• systems running when spaces are unoccupied

Fix:

Upgrade to digital controls or smart BMS (Building Management Systems).

This instantly saves energy.

7. Leaking Ductwork Reducing Cooling Efficiency

Aged or poorly sealed ductwork leaks conditioned air into ceiling voids or plant rooms.

Why it matters:

Duct leakage can waste 20–40% of cooling capacity.

Fix:

Hire specialists to test and reseal ductwork.
TM44 inspectors will always highlight this as a recommended improvement.

8. Obstructed Outdoor Units

TM44 assessors see this constantly:

• units surrounded by stored items

• blocked by fencing

• hidden behind bins

• installed in tight enclosures

• obstructed by vegetation

Outdoor units must breathe.

Fix:

Clear a 1m space around the unit.

9. Failed or Incorrect Thermostat Placement

If thermostats are placed in:

• direct sunlight
• near warm equipment
• behind shelving
• near drafts
• above printers or photocopiers

…they read temperatures incorrectly and overwork the AC.

Fix:

Relocate thermostats to central, shaded, and accurate zones.

10. Lack of Regular Maintenance Logs

TM44 inspectors repeatedly find that businesses have no records of AC servicing.

This impacts:

• compliance
• recommendations
• energy performance
• equipment lifespan
• F-Gas checks

Fix:

Keep digital maintenance logs with:

• filter changes
• coil cleaning
• F-Gas checks
• servicing dates
• repair notes

This makes TM44 inspections faster and cheaper.

11. Aged or Obsolete AC Units

If AC units are:

• older than 10–12 years
• using outdated refrigerants
• rated poorly on energy performance
• visibly corroded or fatigued

…they almost always fail efficiency benchmarks.

Fix:

Plan gradual upgrades using the recommendations in your TM44 report.

Internal links:
👉 Energy Efficiency Upgrade Report (Post-TM44)
https://tm44.uk/services/

12. Inadequate Zoning or Poorly Designed Airflow Layouts

A large open office cooled by a single unit = inefficiency.
A warehouse with no zoning = high running costs.
Meeting rooms cooled constantly when empty = waste.

TM44 inspectors find zoning issues in over 65% of buildings.

Fix:

Use zoning design:

• separate AC control for meeting rooms
• dedicated cooling for server rooms
• airflow planning for warehouses
• occupancy-based cooling

What Happens If You Ignore These Problems?

In 2025, ignoring efficiency problems means:

• higher energy bills
• risk of being non-compliant
• potential fines
• poor comfort for staff or tenants
• faster equipment breakdown
• invalidated warranties
• increased carbon footprint

And importantly:
Your TM44 report will show a lower performance score, which facility managers now take seriously.

How to Fix These Issues Before Your TM44 Inspection

Here’s what we recommend at TM44.uk:

1. Book a Pre-Inspection Health Check

We perform a quick check to identify preventable failures.
👉 https://tm44.uk/get-quote/

2. Schedule Regular AC Maintenance

Create a quarterly routine.

3. Update Controls & Timers

Smart controls save fortunes.

4. Consider Upgrades for Older Units

Your TM44 report will explain ROI clearly.

5. Keep Digital Logs

Inspectors love this it shows good energy management.