Some HVAC problems announce exactly what they are. Others just feel off: the upstairs is stuffy, the system cycles on and off all evening, a vent smells faintly of something burning. When you call a company, the more precisely you can describe it, the faster they send the right person with the right parts.
Sort it by what you hear
| Sound | What it often points to | Source | Where to read more |
|---|---|---|---|
| Rattling outside at the condenser | A loose contactor, a failing compressor or a fan blade hitting something | All Island Comfort | AC repair |
| Screeching from the indoor unit | A blower bearing | All Island Comfort | AC repair |
| Buzzing at the outdoor unit | A capacitor near failure | All Island Comfort | AC repair |
| Knocking or kettling at the boiler | Sediment and other boiler problems | All Island Comfort | Boiler repair |
| Banging or whistling in the heating pipes | A boiler that needs a look | Service Experts | Boiler repair |
Sort it by what you smell
- Gas. Leave the house and call National Grid or 911. This is not a repair call. See emergency heating repair.
- Burning or smoke from the system. Turn the system off and call a company right away, per All Island Comfort.
- Odors or soot around the heating equipment. All Island Comfort lists them among the signs a heating system is due for replacement, not just repair.
Sort it by what you see
- Water on the floor by the indoor unit or air handler. All Island Comfort points to a clogged condensate drain, a failed pump, a cracked pan or restricted return airflow. Turn the system off at the breaker and put a bucket under it.
- Ice on the indoor coil. Low refrigerant, restricted airflow or a stuck valve, by their list. Thaw it with the thermostat off and the fan on.
- The system turns on and off every few minutes. On the cooling side All Island Comfort names a dirty filter, low refrigerant, dirty outdoor coils or a thermostat fault. Short cycling is on their heating list too.
- One room hot, one room cold. On a boiler, that can be a stuck zone valve. On a ducted system, ask the technician to check airflow to that room.
- A big jump in the electric or fuel bill. All Island Comfort lists high fuel or electric bills among its heating repair signs.
Heat pumps and mini splits fit both columns
A heat pump does the heating and the cooling, so one failure can take out both. All Island Comfort’s AC list includes a stuck reversing valve, the part that switches a heat pump between heating and cooling, as a cause of warm air from the vents in summer. Anyone who opens the refrigerant side must be EPA certified to handle refrigerant, which technicians call Section 608 certification. See heat pumps and mini splits.
Service plans and what they buy you
Some Long Island companies sell yearly plans that bundle tune-ups with repair discounts. Two that publish the terms:
| Company | What the plan includes | Source |
|---|---|---|
| Service Experts, Hampton Bays | 15% off services and repairs for Maintenance+ members; standard tune-up $189 | Service Experts (Oct 2026) |
| All Island Comfort, Wading River | Reduced after-hours rates for plan members; plan pricing by phone | All Island Comfort (Oct 2026) |
A plan is worth it if you would have booked the tune-ups anyway. Read what is excluded. Service Experts, for example, excludes oil furnace and boiler tune-ups from its posted price.
Paperwork to expect before the work starts
For a repair, the technician should tell you the problem and the price before turning a wrench. All Island Comfort’s practice is to diagnose, walk you through the findings and give upfront pricing before any repair begins.
For a larger job, New York law adds rules. The Attorney General’s home improvement fact sheet says contracts for work over $500 must be written in plain English and given to you before work starts, with the contractor’s name and address, start and finish dates, the brands and model numbers, and the price. You can cancel until midnight of the third business day after signing, in writing. Deposits taken before the job is substantially done go into an escrow account at a New York bank, unless the contractor provides a bond instead. The AG also tells homeowners never to pay the full price up front.