Pace Arrow Zone AC Not Working - How to Fix Blinking Green LED Error Code

Bottom Line Up Front

The blinking green LED on your 2006 Pace Arrow's zone one air conditioning unit indicates a fault condition in the Coleman Mach control system. Since zone two works normally with a steady green LED, and you've confirmed the thermostat isn't the issue, the problem is most likely either a failed control board in the zone one unit or a faulty thermistor probe. The capacitor is indeed internal to the control box on these Coleman units, so that's not causing your blinking LED issue. Based on the symptoms you're describing, common causes include the control board (approximately 80% likelihood) or the thermistor probe (approximately 20% likelihood).

Root Causes

Coleman Mach air conditioning systems use specific LED blink patterns to communicate different fault conditions. A blinking green LED common causes include thermistor probe failure, control board malfunction, or communication problems between components. Since your zone two unit shows a steady green LED and functions normally, we can rule out power supply issues or thermostat problems.

The thermistor probe on these 2006 Coleman units is a common failure point after 15+ years of service. These probes monitor return air temperature and can develop internal breaks or resistance changes that confuse the control system. However, control board failures are even more common on units this age, especially if the RV has been stored in areas with high humidity or temperature extremes.

The internal capacitor you mentioned is part of the fan motor circuit and wouldn't cause LED diagnostic codes - it would simply prevent the fan from starting if it failed. The blinking pattern you're seeing is definitely a control system diagnostic, not a motor starting issue.

Before You Start

**WARNING: Turn off the breaker to the air conditioning system before starting any electrical work. Even though you're working with low-voltage control circuits, it's safer to work with the main power off.**

First, document the exact blinking pattern and color of any LED indicators - count how many blinks, note any pauses, time the complete cycle, and observe if multiple colored LEDs (red, green, amber) are present as each color indicates different fault types. Different Coleman models use slightly different codes - consult your owner's manual or contact a Coleman dealer for the specific blink code chart for your model number. Take a photo or video if possible, as the pattern may change during your troubleshooting process.

Locate your unit's model and serial number, typically found on a label inside the return air grille or on the unit housing. Coleman Mach units from 2006 could be several different models, and the exact model determines which parts you'll need and the specific diagnostic procedures.

Gather basic tools: screwdriver set, multimeter, flashlight, and have your phone ready to take photos of wire connections before disconnecting anything.

Check that you have good 12V DC power at the unit. While the LED is blinking (indicating the control board has power), verify you're getting 11.5-14.4V DC at the control box connections. Poor connections or voltage drops can cause erratic behavior that mimics component failures.

The Repair Process

**WARNING: Ensure power is disconnected before handling any electrical components.**

Start by locating and testing the thermistor probe, as this is the cheaper and easier component to replace. The probe is usually a small sensor with two wires, often mounted in the return air ductwork or attached to the evaporator coil. Disconnect the probe from its wiring harness and measure its resistance with your multimeter - at room temperature (around 75°F), it should read the specification for your specific model - Coleman uses various thermistor types (1K, 5K, 10K, 20K ohm) depending on the unit (verify exact specification with dealer). If it reads open circuit, short circuit, or significantly different from specification, replace it. A new thermistor probe typically costs $25-40 and takes about 30 minutes to replace.

If the thermistor tests good, the control board is likely failed. On most 2006 Coleman units, the control board may be integrated into the ceiling assembly, though some models have replaceable control boards separate from the full control box assembly. You'll need to replace the entire control box assembly with the correct part for your model (verify with dealer), which includes the board, relay connections, and LED indicator. This part typically costs $150-250 depending on your specific model.

To replace the control assembly, first photograph all wire connections, then carefully disconnect the wire harnesses. The control box is usually held by 2-4 screws and can be lifted out once the connections are removed. Installation is reverse of removal, but pay careful attention to wire routing to prevent pinching when reassembling. Secure all connections and tighten screws hand-tight (do not over-torque small control box screws).

After replacing either component, restore power and test the system. The LED should show steady green within 2-3 minutes of power-up, and the unit should respond normally to thermostat commands. If you still get blinking codes after replacing both the thermistor and control assembly, there may be a wiring issue between the ceiling unit and the thermostat, though this is uncommon.

Professional Help Needed

Consider calling an RV service technician if you're not comfortable working with electrical components or if the blinking pattern doesn't match standard Coleman diagnostic codes. Some newer Coleman systems have unique fault codes that require proprietary diagnostic tools to interpret correctly.

Also seek professional help if you discover the problem extends beyond the control system - for example, if you find damaged wiring in the walls or ceiling, refrigerant leaks, or compressor issues. These repairs require specialized tools and expertise that most DIY mechanics don't have.

Professional diagnosis typically costs $100-150, while repairs can range from $200-600 depending on the failed component. However, given that you've already isolated the problem to the zone one control system, you can likely handle this repair yourself and save $300-400 in labor costs. The total DIY repair cost should be under $300 even if you need both the thermistor and control assembly. Remember to always verify part compatibility with your dealer and follow all manufacturer safety procedures during installation. Before ordering parts, confirm the exact fault code sequence with your Coleman dealer or service manual to ensure accurate diagnosis and prevent unnecessary component replacement.