When a Carrier system in San Jose stops heating, the cause is usually one of two things: a gas furnace that lights and drops out or will not light at all, or a heat pump that ices up or leans on backup heat. Carrier equipment records where it stopped, on a blinking light or on a wall control’s screen. A good repair reads that record first.
What Carrier makes
Gas furnaces in standard and condensing versions, central air conditioning, heat pumps, fan coils, ductless systems, packaged units and thermostats, including Wi-Fi models. The top line, Infinity, links the indoor unit, the outdoor unit and its own wall control so they work as one system. Greenspeed Intelligence is Carrier’s name for its variable-speed, inverter-driven outdoor units within that line.
Carrier furnaces: start with the light
Most Carrier furnaces have a status light on the control board, visible through a small window in the blower door, and a code chart on the door. After several failed attempts to light, a furnace locks itself out for a while before trying again. Turning the power off and on restarts it, but it can also clear the code, so count the flashes first.
On a condensing furnace, the kind vented with plastic pipe, water is part of normal operation. That adds a few causes of no heat a standard furnace never has:
- A clogged condensate trap or drain backs water into the inducer housing, and the pressure switch will not close.
- A sagging vent pipe holds water. The pipes must slope back toward the furnace so condensate drains away.
- A blocked vent or air intake outside: leaves, a bird nest or wasps in the pipe ends stop the furnace from lighting.
- A full drain pan under an attic furnace can trip its float switch, which shuts the system down.
On any furnace, a dirty flame sensor, a cracked igniter or a weak inducer motor are the other regulars. The furnace not igniting guide walks through what is safe to check yourself.
Carrier heat pumps: normal and not normal
In heat mode, a few things look like faults but are not: a defrost cycle with vapor rising from the outdoor unit, and, on Greenspeed units, run times measured in hours at low speed. These are not normal:
| What you see | What usually gets checked |
|---|---|
| Ice that stays on the outdoor coil | Defrost control and coil sensor, then the charge |
| Backup heat running on mild days | Outdoor temperature sensor, settings, a weak heat pump |
| Cool air in heat mode outside defrost | Reversing valve and its solenoid |
| Outdoor fan stopped, unit humming | Fan motor or capacitor on single-speed units |
| Breaker trips when backup heat starts | Heat strips in the fan coil, their relays and wiring |
See heat pump repair and heat pump freezing.
Infinity systems
On Infinity equipment, the wall control keeps a service screen with recent faults and run history, and the system talks over its own data wiring. Replacement boards and motors have to be set up before the system recognizes them.
Refrigerant on newer Carriers
Carrier’s newer ducted equipment uses R-454B, which sits in the mildly flammable class. Indoor units built for it typically carry a refrigerant sensor that runs the blower and stops cooling if it detects a leak, so a faulty sensor can also shut the system down. R-410A systems are still serviced with R-410A, and R-22 equipment draws on a supply that is no longer produced.
Warranty and repair or replace
Heat exchangers usually carry longer coverage than other furnace parts, and parts coverage depends on the install date and registration. Labor is billed separately. A cracked heat exchanger can let combustion gases into the air and normally ends a furnace’s life; a failed compressor on an older heat pump puts replacement on the table. Sensors, igniters, drains and motors are repairs.
Local note: Almaden Valley
Almaden Valley has many larger homes, some over 3,000 sq ft, and a house that size may run two systems or keep its furnace in the attic. The valley floor runs warmer than the hillsides, so a heat pump on a hillside home works harder on winter nights. An attic condensate pan that overflows can stain a ceiling before the float switch stops the system, so look at it now and then.