10 Signs Your AC Has a Gas Leak (And What to Do Before It Destroys Your Compressor)
Refrigerant gas doesn’t evaporate or get consumed — if your AC is low on gas, there’s a leak somewhere in the system. I can’t stress this enough because we see the consequences at Mohammadi Engineering Ltd. almost daily: homeowners in Dhanmondi, Gulshan, Mirpur, and Uttara who kept running their AC with a slow gas leak for months, and then one hot afternoon the compressor just dies. The repair bill jumps from a manageable ৳2,500-4,000 (gas leak fix) to a painful ৳15,000-25,000 (compressor replacement).
Here are the 10 signs that tell you your AC is losing refrigerant — from the early warnings you might ignore to the red alerts that mean you need to shut it off right now.
In This Guide
- 10 signs of AC gas leak with severity ratings
- How technicians detect gas leaks (methods explained)
- Common leak locations in split AC systems
- Repair process and cost breakdown for Dhaka
- R32 vs R22 gas — safety information you should know
- Frequently asked questions
10 Signs of AC Gas Leak
Ice Formation on Copper Pipes or Indoor Unit HIGH
This is the most visible sign. When refrigerant pressure drops, the evaporator coil gets abnormally cold and freezes the moisture in the air. You’ll see ice building up on the copper pipe near the indoor unit, and in severe cases, ice on the unit itself. Running the AC with ice formation can crack the evaporator coil — turn it off and call for AC repair immediately.
Hissing or Bubbling Sound from Indoor Unit HIGH
If you hear a faint hissing sound near the indoor unit or at the pipe connection points, that’s refrigerant escaping under pressure. In larger leaks, it can sound like bubbling water. This means an active leak that’s getting worse. Turn off the AC — the longer it runs, the more gas you lose and the harder (and more expensive) it becomes to fix.
AC Takes Much Longer to Cool the Room MEDIUM
If your AC used to cool the room in 15-20 minutes and now takes 45-60 minutes (or never fully reaches the set temperature), low gas is one of the top suspects. The system has less refrigerant to absorb heat, so cooling capacity drops proportionally. This is usually a slow leak that’s been developing over weeks.
Weak Airflow from Vents MEDIUM
Low gas causes the evaporator coil temperature to drop, which makes the coil ice up (see sign #1). Even before visible ice forms, partial ice buildup restricts airflow through the coil. The fan is running at full speed but air barely comes out of the vents. Don’t confuse this with a clogged filter — check the filter first. If the filter is clean and airflow is still weak, suspect low gas.
Warm Air Coming from Vents Despite AC Running MEDIUM
If the gas level drops very low (below 50% of required charge), the AC essentially stops cooling altogether. The fan blows room-temperature air. At this point, the compressor may still run (making things worse) or the low-pressure switch might shut it off. Either way, this isn’t a “wait and see” situation — the compressor is running dry without adequate oil circulation.
Higher Electricity Bills Without Changed Usage LOW
An AC with low gas runs the compressor longer to try to reach the set temperature — and often never reaches it, so the compressor runs non-stop. A compressor that should cycle on and off runs continuously, consuming 20-40% more electricity. If your DESCO or DPDC bill suddenly spiked and nothing else changed, check your AC’s cooling performance.
Compressor Short Cycling (Frequent On-Off) LOW
Paradoxically, low gas can cause both continuous running AND frequent short cycling. When gas is low, the low-pressure cutout switch trips and shuts off the compressor to protect it. The compressor restarts after pressure equalizes, runs briefly, and trips again. If your AC clicks on and off every 2-5 minutes, low gas is a possible cause (along with a bad capacitor or dirty coil).
Oily Residue on Pipe Joints or Fittings LOW
Refrigerant gas travels through the system mixed with compressor oil. When gas leaks out at a joint or fitting, it often carries a small amount of oil with it. Look for dark, greasy spots on the brass flare nuts where the copper pipes connect to the indoor and outdoor units, and at the service valve on the outdoor unit. This is a telltale sign even if you can’t hear or see the leak.
Uneven Cooling in Multi-Split Systems LOW
Uneven Cooling in Multi-Split Systems LOW
If you have a multi-split system (one outdoor unit connected to multiple indoor units) and one room cools fine while another doesn’t, the problem is likely a gas leak in the branch pipe serving the weak-cooling unit rather than a general gas shortage. This needs a technician to check pressure at each indoor unit’s connection point.
Unusual Smell Near the Indoor Unit MEDIUM
This one needs context. The refrigerant gas itself (R32 or R410A) is mostly odorless. However, when gas leaks and causes the coil to ice up, and then the ice melts, the resulting moisture mixes with dust on the coil and creates a musty, damp smell. If you notice a persistent damp odor that wasn’t there before, especially combined with reduced cooling, get the gas pressure checked.
How Technicians Detect Gas Leaks
When you call us for a suspected gas leak, here’s the detection process we follow at Mohammadi Engineering Ltd.:
Visual Inspection
Check all connection points, flare nuts, valves, and visible pipe sections for oil residue, corrosion, or physical damage. This catches 30-40% of leaks immediately.
Soap Bubble Test
Apply a soapy water solution to all joints and connections. Pressurize the system slightly. Bubbles forming at any point reveal the leak location. Simple, effective, and works for most common leaks at joints.
Electronic Leak Detector
An ultrasonic or heated diode leak detector “sniffs” for refrigerant molecules. This finds micro-leaks that the soap bubble test misses — leaks so small they lose only a few grams per month.
Nitrogen Pressure Test
For stubborn leaks we can’t locate: recover all remaining refrigerant, pressurize the system with nitrogen to 300-400 PSI, and monitor the pressure gauge. If pressure drops, there’s a leak. We then isolate sections (indoor, outdoor, pipe) to narrow down the location.
Vacuum Hold Test
After repairing the leak, we pull a deep vacuum (below 500 microns) and check if it holds for 30+ minutes. If the vacuum holds, the system is sealed. If not, there’s still a leak somewhere.
Where Gas Leaks Actually Happen
| Leak Location | Frequency | Cause | Repair Difficulty |
|---|---|---|---|
| Indoor unit flare nut connection | Very common (35%) | Loose fitting, poor installation, vibration | Easy |
| Outdoor unit service valve | Common (25%) | Valve stem seal failure, corrosion | Easy to moderate |
| Outdoor unit flare nut connection | Common (15%) | Same as indoor — loose or poor joint | Easy |
| Evaporator coil (indoor) | Moderate (10%) | Corrosion, formicary erosion, physical damage | Difficult — may need coil replacement |
| Copper pipe (between units) | Moderate (8%) | Physical damage, corrosion, poor quality pipe | Moderate — pipe section replacement |
| Condenser coil (outdoor) | Rare (5%) | Corrosion from environment, physical damage | Difficult — may need coil replacement |
| Compressor body | Rare (2%) | Internal seal failure | Very difficult — compressor replacement |
The data above is based on our repair records at Mohammadi Engineering Ltd. across Dhaka. Notice that 75% of leaks happen at connection points — the flare nuts. This is directly related to installation quality. Properly brazed or correctly torqued flare joints rarely leak. This is why I always tell people: cheap installation costs you more in the long run.
Repair Process and Cost in Dhaka
| Repair Step | What Happens | Cost (৳) |
|---|---|---|
| Leak detection | Visual + soap bubble + electronic detector | 500 – 1,000 |
| Recover remaining gas | Pump out existing refrigerant (if any left) | Included |
| Repair the leak | Re-torque joint, replace valve, or re-braze pipe | 500 – 3,000 |
| Nitrogen pressure test | Verify the repair is sealed | Included |
| Vacuum pumping | Pull deep vacuum to remove moisture and air | Included |
| Gas recharge (R32, 1.5 ton) | Fill with exact specified weight of refrigerant | 2,000 – 3,500 |
| Total (typical joint leak) | Full repair with gas recharge | 3,000 – 7,500 |
| Evaporator coil replacement | If coil is corroded or cracked (parts extra) | 8,000 – 15,000 + coil cost |
| Compressor replacement | If compressor seal failed (worst case) | 15,000 – 25,000 + gas |
Important: never let anyone just top up your gas without finding and fixing the leak first. Gas refill without leak repair is like pouring water into a bucket with a hole — it’s wasted money and the problem returns in weeks or even days. At Mohammadi Engineering Ltd., we always detect and fix the leak before recharging gas, and we provide a warranty on the repair.
R32 vs R22 Gas: Safety Information
Most ACs sold in Bangladesh since 2020 use R32 refrigerant. Older units may still use R22 (which is being phased out globally). Here’s what you should know about safety:
| Property | R32 | R22 |
|---|---|---|
| Flammability | Mildly flammable (A2L class) | Non-flammable |
| Toxicity | Low toxicity | Low toxicity |
| ODP (ozone depletion) | 0 (safe for ozone) | 0.05 (harms ozone) |
| GWP (global warming) | 675 (lower) | 1,810 (high) |
| Operating pressure | Higher than R22 | Lower |
| Leak risk concern | Keep away from open flames | No flame concern |
R32 is mildly flammable, but in practice, a gas leak from an AC doesn’t create a fire hazard under normal conditions. The gas disperses quickly in open air. However, if you suspect a large R32 leak: turn off the AC, open windows for ventilation, don’t light matches or candles nearby, and call a technician. For smaller leaks detected early, there’s no immediate danger — but the compressor damage risk is the real concern, not fire.
What You Should Do Right Now
If you’ve noticed any of the 10 signs above:
- Turn off the AC — Don’t run it “just a little more” while waiting for a technician. Every minute of operation with low gas damages the compressor.
- Don’t try to fix it yourself — Refrigerant handling requires certification, proper equipment, and knowledge of safety procedures. It’s also illegal in many countries to release refrigerant into the atmosphere.
- Don’t move or bend the copper pipes — If the leak is at a weak spot, moving the pipe can make it worse.
- Note when the symptoms started — This helps the technician estimate how much gas has been lost and whether the compressor has been stressed.
- Check if the AC is under warranty — Some brands cover gas leaks within the first 1-2 years. Have your purchase documents ready.
Suspect a Gas Leak? Call Now for Same-Day Repair
Mohammadi Engineering Ltd. provides leak detection, repair, and gas recharge in a single visit across Dhaka. 24/7 availability with 30-day warranty.
Call: 01859-976686Frequently Asked Questions
The most reliable signs are: ice forming on copper pipes or the indoor unit, hissing sound near connections, the AC taking much longer to cool than before, weak airflow from vents despite a clean filter, and warm air blowing from the AC. If you notice two or more of these signs together, there’s a very high probability of a gas leak. A technician can confirm with a pressure gauge reading.
It can physically run, but it shouldn’t. Running an AC with low gas means the compressor operates without adequate oil circulation (oil travels with the refrigerant). The compressor overheats, bearings wear faster, and eventually the compressor seizes. What could be a ৳3,000-5,000 gas leak repair turns into a ৳15,000-25,000 compressor replacement. Turn off the AC at the first sign of a gas leak.
A standard gas leak repair at a flare joint with gas recharge costs ৳3,000-7,500 in Dhaka (2025 rates). This includes leak detection, joint repair, nitrogen test, vacuum, and gas refill. If the leak is in the evaporator coil and requires coil replacement, costs rise to ৳8,000-15,000 plus the coil cost. Compressor seal failure (rare) costs ৳15,000-25,000.
A simple joint leak repair with gas recharge takes 60-90 minutes. If the leak location is difficult to find and requires nitrogen pressure testing, add 30-60 minutes. Evaporator coil replacement takes 2-4 hours. At Mohammadi Engineering Ltd., most gas leak repairs are completed in a single visit without needing to return with parts.
R32 is classified as mildly flammable (A2L), but a small leak from an AC does not pose immediate danger. The gas dissipates quickly in ventilated spaces. However, for safety: turn off the AC, open windows, avoid open flames or sparks near the unit, and call a technician. The bigger risk from a gas leak is compressor damage, not fire — but basic precautions are still important.
The most common cause (75% of cases) is poor installation — incorrectly tightened flare nuts at the pipe connections. Other causes include: vibration loosening joints over time, corrosion on copper pipes or coils, physical damage to pipes (someone bumped them), manufacturing defects in coils (formicary erosion), and rubber valve seal degradation on the outdoor unit service valves. Proper installation and regular maintenance prevent most leaks.
You can, but it’s a waste of money. The gas will leak out again — sometimes within days for a large leak, or within weeks to months for a small one. Each time the system loses gas, the compressor runs with less oil and takes more damage. Any technician who refills gas without first locating and fixing the leak is doing you a disservice. Always insist on leak detection before gas recharge.