It is 43°C outside. Your AC is humming, the display shows 18°C, and yet the room feels like the inside of a pressure cooker. You call a neighbour, they say "gas khatam ho gaya." You call another, they say "filter saaf karo." Neither is wrong — but neither is complete either.
After repairing over 500 ACs across Samastipur, Dalsinghsarai, Rosera, and Tajpur, our technicians have found that "AC not cooling" is almost never one single problem. It is usually a combination of two or three things happening together. This guide walks through every one of them — in plain language, from a technician's point of view.
Before the reasons, let us understand the context. Samastipur summers regularly touch 44–46°C with high humidity. An AC designed for 35°C ambient temperature is now working far outside its comfort zone. The compressor runs longer, refrigerant pressure spikes, and components that would last 5 years in Delhi might start struggling after 2–3 years here.
This is not a defect in your AC — it is physics. But knowing this helps you understand why annual servicing before summer is not optional in Bihar, it is mandatory.
This is the most common reason we see in Samastipur. The AC uses a refrigerant — either R-22 (older units) or R-410A (newer inverter ACs) — to absorb heat from your room. When this gas leaks, the system cannot absorb heat no matter how hard the compressor works.
Signs of low gas: Ice forming on the copper pipe near the indoor unit, AC blowing slightly cool air but room not reaching set temperature, outdoor unit compressor getting abnormally hot, hissing sound near the indoor unit.
What we do: Pressure test to confirm the leak, locate the leak point (usually at flare joints or valve connections), repair the joint, vacuum the system, and refill with correct gas quantity.
Cost in Samastipur: R-22 gas refill ₹700–₹900. R-410A refill ₹1,200–₹1,600. Leak repair additional ₹300–₹500 depending on location.
In Samastipur, dust levels are high, especially near agricultural areas and kutcha roads. An AC filter that looks fine to the eye may be 70% blocked to airflow. When airflow drops, the evaporator coil behind the filter starts to freeze — and a frozen coil cannot cool your room.
Signs: Very little air coming out of the indoor unit despite fan running on high, visible dust on the louvres, musty smell when AC starts.
What you can do yourself: Remove the front panel, slide out the filter mesh, wash under running water, let it dry completely for 1 hour, and reinstall. Do this every 30–45 days during summer.
What needs a technician: The evaporator coil behind the filter also collects dust over time and needs a chemical wash — this should be done once a year by a trained technician, not with a home garden pipe.
Your outdoor unit throws the heat it pulls from your room into the outside air. If the condenser fins are caked with dust, bird nests, or cotton seed fluff (which is everywhere in Bihar during summer), the unit cannot release heat. The entire system then runs hotter than designed — and cooling efficiency drops by 25–40%.
Signs: Outdoor unit fan running but making strained sounds, compressor heat pipe very hot to touch, AC cooling in the morning but struggling by afternoon.
Fix: High-pressure water wash of the outdoor coil fins — this must be done carefully to avoid bending the delicate aluminium fins. Our technicians carry a fin comb to straighten any bent fins after washing.
The capacitor is a small cylindrical component inside the outdoor unit. It gives the compressor and fan motor the electric kick they need to start and run. When it weakens, the compressor either struggles to start, starts and then shuts off (tripping on thermal protection), or runs at reduced capacity.
Signs: AC starts, runs for 5–10 minutes, then the compressor sound stops but indoor fan keeps blowing warm air, outdoor unit making a humming sound without the compressor running properly.
Fix: Replace the capacitor. Cost in Samastipur: ₹400–₹900 depending on microfarad rating. This is a 20-minute job for a trained technician.
Modern split ACs use a thermistor — a small sensor inside the indoor unit — to read the room temperature. If this sensor fails or gives a wrong reading, the AC thinks the room is already cool and reduces compressor speed (in inverter ACs) or turns the compressor off early (in non-inverter ACs). The result: room stays warm.
Signs: AC runs on a specific mode and refuses to go lower, compressor keeps cycling on and off very frequently, remote shows 18°C but room feels like 28°C.
Fix: Sensor resistance test with a multimeter. If out of range, replace the thermistor — cost ₹200–₹400. Sometimes just repositioning a displaced sensor resolves the issue.
The compressor is the heart of the AC. In Samastipur, where ACs often run 16–18 hours a day during May–June, compressors on 5–8 year old units begin showing wear. A weak compressor cannot build enough pressure in the refrigerant circuit, so even full gas cannot cool the room properly.
Signs: Loud clanking or rattling from the outdoor unit, outdoor unit vibrating more than usual, high electricity bills with poor cooling, AC trips the MCB frequently.
What this means: This is the most expensive repair. Compressor replacement costs ₹3,500–₹8,000 depending on tonnage and brand. Sometimes it makes more financial sense to evaluate whether repairing vs buying a new AC is wiser — we give you honest advice on this.
A 1-ton AC can effectively cool a room up to roughly 120 sq ft in normal conditions. In Samastipur's extreme heat, that number drops to 100 sq ft. Many people install a 1-ton AC in a 160 sq ft room and then wonder why it never reaches the set temperature — the unit is working at 100% capacity all the time but is simply too small for the heat load.
Signs: AC runs continuously without ever shutting off, room temperature stabilises around 26–28°C even on 18°C setting, no gas leak, no dirty filter — everything checks out but room is not cool.
Fix: No repair can fix this. The solution is either upgrading to a 1.5-ton unit, adding ceiling fans to help air circulation, or reducing the heat load (better curtains, closing the room properly).
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