To Next PageTo Next Page
What to do if both heating and cooling are energized when calling for cooling on Carrier Thermostat?
If both heating and cooling are energized when calling for cooling, the thermostat is likely configured for a heat pump. Configure the thermostat for non-heat pump operation (Table 2, Step 3).
How to reset the clean filter message on a Carrier 33CS?
To reset the 'Clean Filter' message on your Carrier Thermostat, press the Reset Filter button to reset the blower operation timer to 0 hours.
Why is my Carrier Thermostat displaying '--'?
If your Carrier Thermostat is displaying '--', it indicates that the temperature sensor reading is out of range. Check the sensor for damage and inspect the sensor wiring. Try cycling power to the thermostat. If the display doesn't clear, replace the thermostat.
How to fix a Carrier Thermostat display that only shows the clock?
If your Carrier Thermostat display only shows the clock, this setting is configured in Advanced Setup Step 3. To resolve this, change the Display Blanking configuration to Off.
What to do if a commercial heat pump unit runs in reverse or heating is always on when controlling it with Carrier 33CS?
If controlling a commercial heat pump unit, and the unit runs in reverse or heating is always on, ensure that the Heat Pump Option on the thermostat is turned OFF.
What to do if resistor L3 is burned out on Carrier 33CS Thermostat?
If the resistor labeled “L3” on your Carrier Thermostat is burned out and brown, and the thermostat won't work, it means the thermostat has been wired incorrectly and the circuit board is burned out. You must replace the thermostat.
What to do if my Carrier Thermostat is not cooling?
If your Carrier Thermostat isn't cooling, select COOL mode and decrease the cooling set point to 10 degrees below room temperature. Simultaneously press the Fan and Up buttons to disable any timers. Check for 24 vac at the Y/Y2 terminal. If voltage is present, the thermostat is operating correctly, and the problem is with the wiring or equipment. If 24 vac is not present, replace the thermostat.
What does E2 mean on my Carrier 33CS and how to fix it?
The 'E2' error on your Carrier Thermostat indicates a brownout condition or that the voltage is too low for the thermostat to operate. Check the wiring and ensure there is 24 vac at the R and C terminals. The E2 error will clear 15 seconds after acceptable power levels are restored.
How to fix a Carrier 33CS with no display?
If the display on your Carrier Thermostat is not illuminated, check for 24 vac at the R terminal connection. Terminal R must be connected for proper thermostat operation.
How to fix Carrier Thermostat when heating equipment tries repeatedly to turn on?
If, when using 4 wires (R, G, W, Y), the heating equipment tries repeatedly to turn on but cannot with your Carrier Thermostat, it means there isn't enough power available. To fix this, connect a 270-ohm, 10-watt power resistor at the air-conditioning equipment between terminals Y and C (non-heat pump applications only).
Guidance on selecting the optimal location for mounting the thermostat.
Instructions for configuring the thermostat's DIP switches.
Detailed steps for physically installing the thermostat unit.
Using multiple sensors for accurate average temperature readings.
Configuring advanced thermostat settings and options.
Diagrams illustrating wiring connections for various models.
Diagram showing the layout of components on the thermostat circuit board.
System settings like F/C, fan modes, and lockout features.
Procedures for verifying thermostat functionality and settings.
Setting up daily heating and cooling schedules.
Temporarily changing schedules and post-installation tasks.
Controls and timers for hold, fan, mode, and protection.
Initial checks and troubleshooting error messages.
Resolving problems related to the thermostat's LCD display.
Diagnosing why heating or cooling systems are not activating.
Guidance on selecting the optimal location for mounting the thermostat.
Instructions for configuring the thermostat's DIP switches.
Detailed steps for physically installing the thermostat unit.
Using multiple sensors for accurate average temperature readings.
Configuring advanced thermostat settings and options.
Diagrams illustrating wiring connections for various models.
Diagram showing the layout of components on the thermostat circuit board.
System settings like F/C, fan modes, and lockout features.
Procedures for verifying thermostat functionality and settings.
Setting up daily heating and cooling schedules.
Temporarily changing schedules and post-installation tasks.
Controls and timers for hold, fan, mode, and protection.
Initial checks and troubleshooting error messages.
Resolving problems related to the thermostat's LCD display.
Diagnosing why heating or cooling systems are not activating.
The Carrier 33CS Commercial Thermostat is a wall-mounted, low-voltage, programmable device designed to maintain room temperature by controlling HVAC (heating, cooling, and ventilation) systems. It offers 7-day programming capabilities, allowing for separate heating and cooling set points, as well as auto-changeover functionality, to optimize energy savings in both occupied and unoccupied periods.
The thermostat supports up to four time/temperature settings per 24-hour period and stores programs for seven independent days. It does not require batteries for memory retention; during power interruptions, its internal memory stores comfort schedules indefinitely, and the clock continues to run for at least 72 hours.
The device can be configured for various equipment setups, ranging from single-stage heating and cooling to three stages of heating (heat pump only) and two stages of cooling. It comes factory-configured for one stage of cooling and one stage of heating.
Installation begins with selecting an appropriate location, ideally about 5 ft from the floor, in a frequently used room, and on an inside partitioning wall, away from windows, direct sunlight, drafts, or areas with poor air circulation.
Before physical installation, the installer must configure four small DIP (Dual In-line Package) switches located on the back of the circuit board. These switches control:
After DIP switch configuration, the thermostat is physically installed by routing wires through the mounting base, securing it to the wall, and connecting wires to the appropriate terminals. Power is supplied by the HVAC unit, typically 24 VAC. Upon power-up, the thermostat displays the selected setup mode (e.g., AC Single-Stage, HP Single-Stage, A2 Air Conditioner 2-Stage, H2 Heat Pump 2-Stage) for a few seconds.
For applications requiring temperature averaging, the thermostat supports configurations with either four or nine sensors. Carrier-specific sensors must be used, either singly or in multiples of four or nine, with total sensor wiring not exceeding 1000 feet.
The thermostat offers several configuration options, typically set during installation and not meant for user modification. Accessing configuration mode involves pressing and holding the Fan button for approximately 10 seconds. The room temperature display will show dashes (--), and the thermostat will automatically exit this mode if no button is pressed for 10 seconds. Configurable options include:
The device is designed for reliability and ease of use, with clear operational indicators and diagnostic capabilities to assist in troubleshooting.
General| Type | Non-programmable |
|---|---|
| Power Source | 24 VAC |
| Stages | 1 Heat/1 Cool |
| Voltage | 24 VAC |
| Accuracy | ±1°F |
| Display | Digital |
| Compatibility | Single Stage Systems |
| Temperature Range | 45°F to 90°F |
| Programmability | No |
