Inverter ACs have quietly become the most popular way to heat homes in Islamabad and Rawalpindi. With gas pressure dropping every winter and gas heaters carrying real safety risks, many families now switch their AC to heat mode from late October until March. It is a smart choice, but an AC that has run hard all summer is rarely ready to heat efficiently without some attention.
This guide explains why a pre-winter AC service matters, what a proper service should include, the problems people most often notice when they first switch to heat mode, and a few simple habits that keep your electricity bill under control.
Can every AC heat?
Not every AC can. Only units described as “heat and cool” or “heat pump” models can warm a room. Most inverter ACs sold in Pakistan in recent years are heat and cool, but many older non-inverter units are cooling only. Check your remote for a sun symbol or a “Heat” option in the mode button, or look for the model details on the indoor unit’s sticker. If your AC is cooling only, it will not heat no matter what setting you choose.
Why service your AC before winter?
After months of summer use, the filters, indoor coil and outdoor unit collect dust, pollen and pollution. In cooling mode, a dirty AC just cools less. In heat mode, the effects are often worse: warm air output drops, the compressor works harder, and your bill climbs. A dirty outdoor coil also struggles more with the cold, which can lead to frequent defrost cycles and long pauses in heating.
A service in October or early November also catches problems such as a slow refrigerant leak or a weak capacitor before the coldest weeks, when technicians are busiest and a breakdown is most uncomfortable.
What a proper winter service should include
A good AC service is more than a quick spray of water on the filters. Ask your technician to cover the following: cleaning or washing the indoor filters; cleaning the indoor coil and blower so air flows freely; cleaning the outdoor unit’s coil and fan, and clearing leaves or debris around it; checking the refrigerant pressure, since low gas is one of the most common reasons an AC heats poorly; checking the electrical connections, capacitor and wiring; making sure the drain pipe is clear; and running the unit in heat mode to confirm it actually blows warm air.
Be cautious of anyone who recommends a full gas refill without first checking pressure or finding a leak. If gas is low, there is a leak somewhere, and refilling without fixing it only buys you a few weeks.
Common problems when you first switch to heat mode
The AC blows cold air for the first few minutes. This is normal. Most units hold the indoor fan until the coil warms up so they do not blow cold air at you, but some start gently cool. Give it five minutes before deciding something is wrong.
Heating stops and steam comes from the outdoor unit. Also usually normal. On cold, damp mornings ice forms on the outdoor coil, and the AC runs a defrost cycle to melt it. The indoor unit pauses for a few minutes and the outdoor unit may release steam or water. If this happens very frequently, a dirty outdoor coil or low gas may be the cause.
Weak warm air or the room never gets comfortable. Dirty filters, low refrigerant or an undersized unit are the usual suspects. A 1-ton AC that cools a small bedroom well may struggle to heat a large lounge on a cold night.
Strange smells when heat is first turned on. A dusty or musty smell for the first few minutes is common after the unit has been idle, and a clean coil and filter reduce it. A burning plastic or electrical smell is not normal: switch the AC off at the breaker and have it checked.
Water leaking from the indoor unit. This points to a blocked drain pipe or a dirty coil, and should be fixed before it damages your wall or ceiling.
Habits that keep your winter bill under control
A few simple habits make a noticeable difference. Set the temperature to a comfortable 22 to 24°C instead of the maximum; inverter ACs are most efficient when they hold a steady temperature rather than working flat out. Close doors and curtains in the room you are heating, and avoid heating empty rooms. Clean the filters every two to three weeks during heavy use, since dust builds up quickly in winter too. Keep the outdoor unit clear of covers, plants and stored items, because it needs open airflow to pull heat from outside air. And if you plan to cover the outdoor unit during rain, remove the cover before turning the AC on.
When to call a technician
Cleaning the filters is an easy job you can do yourself. Anything involving refrigerant, electrical parts, the outdoor coil or a recurring fault is best left to a trained technician. Working on an AC involves high voltage and pressurised gas, and a wrong fix can be costly.
If you want your AC ready for winter, Apni Chhat Home Services offers AC servicing and repair across Islamabad and Rawalpindi. For gas geysers, see our guide on why a gas geyser stops working in winter.
Where the install is the real problem
In newly handed-over houses, in sectors like F-17, and in quickly finished builds across Bahria Town, a unit that heats or cools badly is more often an installation fault than a worn-out machine: no proper vacuum before charging, a drain line run flat, or an outdoor unit with no room to breathe. In flats, as in much of E-11, where the outdoor unit and the drain can go is the limiting factor. We service and install across Islamabad and Rawalpindi at published rates.