Why is my AC throwing hot air in Vadodara heat?
Residents of Vadodara often encounter air conditioning failures specifically during peak summer months (April–June), where ambient temperatures frequently exceed 42°C (108°F). When an AC unit runs but discharges warm or ambient-temperature air, the issue is typically mechanical rather than electrical control failure.
The two most statistically probable causes for this phenomenon in high-heat regions like Gujarat are electrolytic capacitor failure due to thermal stress, and refrigerant (gas) leakage caused by vibration or corrosion.
1. Capacitor Failure
A Start/Run Capacitor is a cylindrical electrical component that stores energy to provide the initial torque required to start the AC compressor motor. In split and window AC units, this is the most common point of failure when the fan is working but the air is not cold.
The Thermal Stress Factor
Capacitors contain a dielectric fluid that is sensitive to heat. In Vadodara, outdoor units (ODUs) are often exposed to direct sunlight where internal casing temperatures can surpass 60°C. This extreme heat prevents the capacitor from dissipating its own electrical heat, leading to the expansion of the dielectric fluid and eventual bulging or open-circuit failure.
Once the capacitor fails, the compressor attempts to start but cannot overcome the mechanical inertia (Locked Rotor Amps), causing it to overheat and trip on its internal thermal overload protector.
Technical Symptoms
- The Hum of Death: The outdoor unit emits a loud humming or buzzing noise at regular intervals (every few minutes) as the compressor tries to start but fails.
- Fan Only Operation: The outdoor fan spins at full speed, but the distinct vibration and sound of the compressor engaging is absent.
- Warm Air Discharge: The indoor unit blows air at room temperature because the refrigeration cycle is not active.
2. Gas Leakage (Refrigerant Loss)
Air conditioners operate on a closed-loop system. Contrary to popular belief, gas is not “consumed” like fuel in a car. Low gas levels invariably indicate a physical leak in the copper tubing, flare nuts, or welding joints.
Why Leaks Occur
Vibration Cracks: The compressor generates significant vibration. Over time, this mechanical stress can cause microscopic cracks in the copper U-bends of the condenser coil.
Formicary Corrosion: In humid environments or areas with open drainage (common in certain older parts of Vadodara), volatile organic compounds react with moisture and copper to create microscopic pinholes in the coils, often resembling ant nests.
Diagnostic Signs
| Symptom | Technical Explanation |
|---|---|
| Ice Formation | Ice builds up on the discharge line (thin pipe) or evaporator coil. Low pressure causes the refrigerant’s boiling point to drop below freezing, solidifying atmospheric moisture. |
| Hissing Sound | A distinct hissing noise near the indoor unit usually indicates an active, high-pressure leak in the evaporator coil. |
| Oil Stains | Refrigerant oil circulates with the gas. Dark, oily patches on pipe joints or flare nuts are a definitive visual marker of a leak location. |
3. Vadodara Contextual Factors
The geography of Vadodara contributes specific stressors to HVAC systems. The combination of industrial pollution (from nearby belts) and high summer heat creates an acidic atmospheric mix that accelerates the oxidation of copper condensers.
Furthermore, voltage fluctuation in certain residential zones during peak load hours (afternoons in May) can cause capacitors to degrade faster than their rated lifespan.
References & Further Reading
- ASHRAE Handbook – HVAC Applications (2019), Chapter 44: “Unitary Air Conditioners and Heat Pumps”.
- Electrical Engineering Portal. “Capacitor Failure Modes in Inductive Loads”.
- Bureau of Energy Efficiency (BEE) India guidelines for AC maintenance.
Last edited: February 7, 2026