When an RV air conditioner clicks but fails to start, common culprits include a weak capacitor, low voltage, or a control fault.
Your rooftop unit clicks, the fan may twitch, then silence. This guide shows fast checks, safe fixes, and when to call a tech. You’ll see what that click means, what usually breaks, and the exact order to test parts without wasting time.
RV Air Conditioner Clicks And Won’t Start — Quick Checks
That click is a relay or contactor trying to hand power to the fan or compressor. If the motor can’t spin or the control blocks the start, you hear the sound but nothing runs. Start with power, then capacitors, then controls, then motors.
| Symptom | Most Likely Cause | What To Do First |
|---|---|---|
| Single click, no fan | Blower capacitor or seized fan | Kill power, spin fan by hand, test fan cap |
| Click, brief hum, stops | Compressor start/run capacitor weak | Discharge and test caps; replace if out of spec |
| Rapid clicks | Low shore power or loose wiring | Measure voltage under load; tighten terminations |
| Fan runs, no cold air | Compressor not starting | Test start gear and contactor; inspect overload |
| Breaker trips on start | Shorted cap or locked compressor | Inspect caps for bulge; isolate compressor leads |
| Thermostat dead | No 12V control power/reset needed | Check fuse/battery; perform thermostat reset |
Safety First Before You Open The Shroud
Pull the pedestal plug or switch off the breaker. Confirm zero volts with a meter. Discharge capacitors using a bleed resistor rated for the job. Wear eye protection and insulated gloves. If you’re not comfortable around line voltage, stop here and book service.
Tools You’ll Need
- Digital multimeter with capacitance mode and clamp ammeter.
- Bleed resistor or discharge tool rated for AC capacitors.
- Insulated screwdriver set and nut drivers.
- Non-contact voltage tester and a headlamp.
- Replacement capacitors matched to microfarads and voltage.
Understand The Click: What’s Firing Inside
Inside the upper unit, a control board or a simple mechanical switch energizes the fan and the compressor. The sound you hear is the relay snapping shut. If supply voltage sags or a capacitor can’t provide the kick, a protector opens and you’re back to quiet.
Power And Voltage: Start Here
Most roof units draw around 13–16 amps while running, and far more for a split second on startup. On a 30-amp hookup, a water heater or microwave can starve the air conditioner during that surge. Try these steps:
- Unplug other heavy loads. Set water heater to gas only and switch off the converter’s high-draw modes.
- Watch voltage at the pedestal and inside the coach while the unit tries to start. Anything dipping near 105–108 V under load points to supply trouble.
- Test with a different pedestal or a quality generator. If the unit starts cleanly, the issue was supply.
Manufacturer data shows typical draw near 12.8–13.9 amps for 13.5K–15K BTU models, with brief inrush above that range. A soft-start module can trim that spike by ramping the compressor windings each cycle.
Capacitors: The Most Common Failure
Run and start capacitors store energy to help motors spin up and stay smooth. Heat and age dry them out. Signs of failure include bulging tops, oil residue, or a meter reading outside the labeled microfarads. Combo cans have three tags: C, FAN, and HERM.
How To Test The Can Safely
- Kill power and discharge the part with a resistor. Never short the terminals with a tool.
- Label or photograph the wiring to the C, FAN, and HERM lugs.
- Remove leads and test with a capacitance meter. Replace any unit outside ±6% of nameplate.
- On systems with a separate booster, test both the run and the start pieces.
Fresh capacitors often revive a blower or get a compressor past the hump. If a new part still leaves you with clicks, move to the contactor and control path.
Controls, Contactors, And Thermostats
Wall controls send a low-voltage start signal. A control board then drives a contactor or solid-state switch. Corroded spades, a pitted contactor, or a failed time-delay module can cause that single click with no run. Many wall modules also support a reset combo that clears faults.
Fast Control Checks
- Verify 12 Vdc to the wall module and board. Replace a blown fuse or charge the house battery bank.
- Pull and reseat low-voltage harnesses. Inspect spade lugs for heat discoloration.
- Reset the wall control using the button combo for your model.
- With power off, check continuity across the contactor coil and inspect contacts for carbon pits.
Common Thermostat Resets
Many wall modules clear odd behavior after a keyed reset. Typical steps: power the system down, hold the mode button and the up arrow, then restore power until dashes show on the screen. Exact steps vary by brand, so check your booklet or the maker’s site.
Fan Won’t Spin Or Spins Slow
If the blower won’t launch, air stalls in the coil and the compressor protector opens. Debris, dry bearings, or the wrong fan capacitor value can all stall the motor. Confirm the wheel spins freely by hand and replace a dragging motor before cycling the compressor again.
Compressor Clicks And Stalls
A hermetic motor needs a larger kick than the fan. Weak start gear, low voltage, or a hot overload will stop it at the first grunt. After capacitor checks, verify the thermal protector on the shell, then test windings with an ohmmeter from C-R-S for open or shorted conditions. Each lead should also show no continuity to the shell.
When A Soft Start Makes Sense
On small generators or weak park power, a soft-start module tames inrush by feeding a controlled ramp to the windings. Many owners install one to run a 13.5K unit on lighter sources. It won’t fix a dead capacitor or a bad motor, but it can stop nuisance clicking on marginal power.
Step-By-Step Troubleshooting Flow
- Confirm shore power or generator output is stable and near 120 V under load.
- Eliminate other loads; repeat the start test.
- Open the shroud; inspect wiring, connectors, and the capacitor can.
- Discharge and test run/start capacitors; replace if out of spec or swollen.
- Check the contactor and control board outputs to fan and compressor.
- Test fan motor spin and amperage with the correct capacitor in place.
- Test compressor windings and overload; evaluate with an ammeter during a start attempt.
- If power is marginal, add a soft-start kit matched to your model.
Expected Amps And Power Sources
Running current varies by model and weather. A 13.5K unit often sits near 12–13 amps; a 15K unit near 14 amps. Start surge is the spike that trips a weak pedestal or skinny cord. On 30-amp service, keep big draws off during starts. On 50-amp rigs, split loads across legs.
| Item | Typical Range | Notes |
|---|---|---|
| Running amps (13.5K) | ~12–13 A | Higher on hot days |
| Running amps (15K) | ~13–15 A | Spec sheets list values |
| Line voltage | 108–132 V | Below 108 V causes trouble |
| 30-amp shore power | 3,600 W | One big AC plus light loads |
| 50-amp shore power | Up to 12,000 W | Two legs for larger rigs |
| Soft-start effect | Start spike reduced | Helps small generators |
Wire, Cords, And Voltage Drop
Long, skinny cords waste voltage and invite chatter. Use the shortest run you can and heavy-gauge cable sized for the length. Loose terminations at the pedestal, breaker, or transfer switch also cause dips. A quick torque check often cures odd cycling.
Quick Do-Not-Do List
- Don’t short a capacitor to discharge it; use a proper resistor.
- Don’t keep forcing starts with low voltage; that overheats windings.
- Don’t swap microfarad values “close enough”; match the label exactly.
- Don’t run through long coiled cords; heat and drop get worse.
Parts That Commonly Fix The Click
Most no-start cases end with a new run can, a new booster, a fresh contactor, or a blower motor. Boards and thermistors fail less often but still show up. Match microfarads and voltage. Keep spare caps in the coach with insulated jumpers and a bleed resistor.
When To Call A Pro
Call in help when windings test short to ground, when the contactor chatters with solid power, or when a thermostat reset won’t revive the call for cool. A licensed tech can weigh refrigerant and replace sealed components that owners shouldn’t open.
Helpful Official References
Manufacturer guides offer wiring labels, reset steps, and specs. See the Coleman-Mach FAQs for common issues and a reset overview. Keep model manuals nearby for wiring diagrams, amp ratings, and capacitor values.
Prevent The Next Click-And-No-Start
Keep manuals; they show wiring, reset keys, and specs.
Simple Habits
- Pop the shroud each season to blow dust from coils and tighten spades.
- Scan the capacitor can for swelling; replace aging parts in pairs.
- Keep a log of amperage at typical setpoints so odd numbers stand out.
- Use heavy-gauge power cords sized for the run to the pedestal.
Startup Strategy
- Pre-cool the cabin early in the day so cycles are shorter later.
- Stage loads: fridge on gas, water heater on gas, microwave off during starts.
- Consider a soft-start kit if you camp on small generators or sketchy posts.