Detectors
A guided diagnosis for RV techs. Each step is a check, a reading or a question.
- Which detector, and what is it doing? RVs carry three: LP (low on the wall, 12V), CO (12V or battery), and smoke (9V battery). Each has its own chirp language. Expect: Safe-T-Alert LP: solid green normal, flashing red plus continuous tone alarm, red and green alternating plus two beeps every 15 s is a malfunction, flashing yellow is warm-up
- What is the LP detector showing? Watch the light and count the beeps. Expect: Solid green within a couple of minutes of power-up
Causes and repairs
LP alarm: treat it as real
Shut the cylinders off, open windows and the door, no flames or switches. Then find the source. False alarms come from hairspray, cleaning sprays, a dog's flatulence (really), a new carpet, or a low battery under about 10 V.
Tools: leak detector, manometer
Ventilate. Leak test the gas system (see the LP guide). If no leak and the detector alarms again with the gas off, check battery voltage and the detector's date; replace a detector past its life.
LP detector malfunction
Sensor failed or contaminated. The mute button does nothing in a malfunction.
Tools: multimeter
Check 12V at the detector. Replace the detector; they are not repairable.
Low battery chirp
The coach battery is low. The detector is the first thing to complain.
Tools: multimeter
Charge the battery. Fix the drain (see 12V).
End of life
Sensors wear out. The date on the back tells you. The detector chirps until it is replaced.
Tools: none
Replace with a current unit. Record the install date on it.
Warm-up
Flashing yellow for a minute or two after power-up is normal.
Tools: none
Wait for solid green.
CO alarm: get out, then find it
Everyone out, fresh air. CO sources in an RV: a generator exhaust blowing toward the coach or a neighbor's, a furnace with a cracked exchanger or blocked exhaust, a water heater or fridge flue dumping inside, a stove or oven run for heat, a catalytic heater.
Tools: CO meter
Shut off the generator and all gas appliances. Ventilate. Find the source with a CO meter before anyone sleeps in it. A furnace that soots or a flue that smells is a stop.
Chirping CO or smoke detector
A single chirp every 30 to 60 seconds is a low battery or end of life. Smoke detectors use a 9V; many CO detectors are 12V with a backup.
Tools: 9V battery
Replace the battery. If it keeps chirping, check the date and replace the unit.
Detector has no power
12V detectors are on a fuse, often shared with something else, and sometimes on the disconnect. Battery units just need a battery.
Tools: multimeter
Check the fuse and 12V at the detector. If the disconnect kills it, that is by design on many coaches; tell the customer.