In the Sultanate of Oman, we are famous for our scorching summers. But what happens when the temperatures drop in January and February?

While we don’t face freezing blizzards, our air conditioners still play a vital role during winter—either by providing heating on chilly desert nights or simply filtering the dusty air. However, neglect during these months often leads to expensive failures just as summer returns.

At Rubo Al Hail International Enterprise, we believe year-round maintenance is the key to longevity. As the leading HVAC wholesale dealer in Oman, here are the most common issues we see during the winter and how to fix them with the right parts.

Issue 1: “Heating Mode” Failure (No Warm Air)

Many split units in Oman are “Heat Pumps,” meaning they can reverse their cycle to blow warm air.

• The Symptom: You switch the remote to “Heat” (Sun symbol), but the unit blows cold air or doesn’t start at all.
• The Cause: This is often due to a stuck Reversing Valve (the part that switches the flow) or a failed solenoid coil.
• The Fix: A technician needs to test the valve. If it’s faulty, it must be replaced. We stock compatible Reversing Valves and Coils for most major brands used in the Gulf.

Issue 2: The “Musty Smell” (Mold Growth)

When the AC is turned off during the cooler weather, the moisture left inside the unit combined with darkness creates a perfect breeding ground for mold.

• The Symptom: A foul, musty odor when you turn the unit on for the first time in weeks.
• The Fix: Don’t just cover the smell with air freshener. You need to kill the mold. Use a professional-grade A/C Chemical Coil Cleaner to sanitize the evaporator coils and drain pan.

Issue 3: Reduced Airflow Due to Dust

Just because it’s winter doesn’t mean the dust stops. If you ran your AC hard all summer and didn’t clean the filters before winter, they are likely clogged solid.

• The Symptom: Weak airflow and the unit sounds louder than usual.
• The Fix: Check your filters immediately. If they are grey and blocked, wash or replace them. We stock a full range of Washable and Media Air Filters.

Issue 4: Outdoor Unit Damage & Corrosion

Winter in coastal cities like Muscat and Salalah brings higher humidity and salt spray, which accelerates corrosion on the outdoor unit’s fins.

• The Symptom: Visible rust on the outdoor condenser or the unit struggles to exchange heat efficiently.
• The Fix: Apply an Anti-Corrosive Coating Spray to the fins to protect them. If the fins are already crumbling, you may need to replace the entire Condenser Coil—available at our showroom.

Issue 5: Electrical Issues (Isolator Switches)

The outdoor “Isolator Switch” (the waterproof switch on the wall) takes a beating from the summer sun. By winter, the plastic is often brittle and cracked, allowing winter rain or dew inside.

• The Symptom: The breaker trips randomly, or there are visible sparks/burning marks on the switch.
• The Fix: This is a dangerous fire hazard. Replace the damaged switch immediately with a heavy-duty, weatherproof Isolator Switch from Rubo Al Hail.

Issue 6: Unwanted Guests (Pest Intrusion)

As the desert temperature drops at night, pests like rats, birds, and geckos seek warmth. Your outdoor AC unit or the ceiling void where your ducts are located is the perfect shelter.

• The Symptom: Chewed insulation, scratching noises above the ceiling, or the unit suddenly stops working (wires chewed).
• The Fix: You often need to replace damaged Flexible Ducts or re-wire the control cables. We stock Armoured Cables and sturdy Ducting to repair pest damage effectively.

Issue 7: The “Sewer Smell” (Dry Drain Traps)

This is a very specific issue when ACs are turned off for weeks. The U-trap in your drain line relies on water to block sewer gases. When the AC stops producing condensation, that water evaporates.

• The Symptom: A foul, sewage-like smell coming from the AC vent, even though the unit is clean.
• The Fix: Pour water down the drain line to refill the trap. If the line is blocked by dried algae or sludge, use a Drain Line Cleaner or high-pressure nitrogen to clear it.

Issue 8: “Hard Start” Struggles

Even in Oman, oil inside the compressor becomes thicker in cooler weather. If your unit’s Capacitor is weak (but not dead), it might have worked in summer but will fail to kick-start the compressor against this thicker oil in winter.

• The Symptom: The outdoor unit hums loudly for a few seconds and then clicks off (trips on thermal overload).
• The Fix: Replace the weak capacitor immediately. For older units, installing a Hard Start Kit (available at Rubo Al Hail) gives the compressor the extra boost it needs to start smoothly.

Issue 9: Seized Fan Motors

Mechanical parts like to move. When a fan motor sits idle for 3-4 months during winter, the grease in the bearings can harden, or dust can seize the shaft.

• The Symptom: When you finally turn the AC on, the fan blades don’t spin, or they make a grinding noise.
• The Fix: Sometimes lubrication helps, but usually, the motor needs replacing. We stock Universal Fan Motors compatible with most Omani window and split units.

Issue 10: The “Silent” Gas Leak

Small pinhole leaks often go unnoticed in summer because you are constantly topping up the gas. However, if a unit sits with a leak all winter, it will be completely empty by March.

• The Symptom: The unit runs but produces zero cooling (or heating).
• The Fix: Don’t just refill it! The leak must be found and brazed. We supply Copper Brazing Rods, Torches, and Leak Detection Spray to fix the root cause before refilling with expensive refrigerant.

Conclusion: Don’t Neglect Your AC in Winter

Winter is the best time to perform maintenance because you aren’t relying on the AC for survival. A small fix now prevents a major breakdown in May.

Rubo Al Hail International Enterprise is your trusted source for all HVAC maintenance supplies.

Get Your Parts Today: 📍 Al Baladiya St, Muscat, Oman 📞 Call/WhatsApp: +968 95076026 🌐 Shop Online: www.ruboalhail.com