Troubleshooting · SFD200 / SFD201
Most instruments sent back to us turn out to be working. Pick what you are seeing and work down the list in order — the checks are ordered by how often they turn out to be the answer.
Start with the 15-second check. It splits this into two completely different problems, and saves you working through checks that do not apply.
First — does it respond to anything at all?
A brief release from a charged system or a service hose works for refrigerant. On the SFD201, hold an unlit gas lighter near the probe for a moment. Do this in a ventilated area and keep the release short.
Manual §11Did it respond?
It responds — so this is technique
Ordered by how often each one turns out to be the answer.
Switch off fans, close doors, and shield the joint from wind. Moving air carries the leak away before it reaches the probe.
Manual §9.3The detector zeroes itself at start-up. Switch it on next to the leak and it treats the leak as normal background, then barely responds. If you did, move to clean air and press ZERO there.
Manual §9.1, §9.7Held about ¼ in (6 mm) from the surface. Faster than this and you pass straight over the leak. This is the pace:
Pass the probe right around the fitting rather than along one side. Gas can travel in any direction once it has left the joint, and a single pass can miss it.
Nothing leaks out of a system that is empty or switched off. Oil, water and cleaning solvent each produce a response of their own — alcohol-based cleaners and leak-detection sprays as strongly as refrigerant itself.
For refrigerant, start on SENS-H. Press HI/LO to switch. For combustible gas on the SFD201, start on SENS-L.
No response to a known source either
A metal-oxide sensor that has not been powered for a long time reads low until it has been running for a while. Leave it switched on in clean air for several hours, then try the known-source check again. This is normal behavior, not a fault, and it is the most common reason a detector seems insensitive.
Manual §9.2There is no detection at all during the countdown. Wait for the second beep and for the display to read 0 PPM.
Full procedure: user manual §9.3. Download the manual
Almost always the baseline, or something in the air that is not refrigerant.
After it has been running for a while the reading can drift, even in clean air. Hold the probe in clean air away from the suspected leak and press ZERO.
Manual §9.7Zeroing in contaminated air sets the baseline on the very gas you are looking for. The leak will then read as nothing, and everywhere else will look wrong.
Moving air, steam, solvent, perfume and strong odors all disturb the sensor. Alcohol-based cleaners, coil cleaner and leak-detection spray respond as strongly as refrigerant itself.
Manual §1, §9.3The SFD201 also responds to natural gas, LPG, propane, gasoline vapor and alcohol. In a workshop that includes fuel vapor and solvent on the bench. Try SENS-L to cut the background.
Press HI/LO. High sensitivity is for finding the leak; once you are in the right area, low sensitivity makes it easier to pinpoint.
Once the leak is found, take the probe out of it. Prolonged exposure to a high concentration leaves the sensor reading high for a long time afterwards.
Manual §11There are two things to check: that it starts up correctly, and that it responds to a source you already know is there.
Hold power for 3 seconds. The display briefly shows all segments for one second and the buzzer beeps. A 30-second countdown runs — there is no detection during it. A second beep marks the end. The display then shows 0 PPM and the current sensitivity setting.
A brief release from a charged system or a service hose works for refrigerant. On the SFD201, hold an unlit gas lighter near the probe for a moment. Do this in a ventilated area and keep the release short. It takes fifteen seconds and it is the only way to know the instrument is awake before you rely on it.
Manual §11The buzzer beeps faster as the concentration climbs. You do not have to watch the screen to work — which also answers the problem of reading the display outdoors.
Leave it switched on in clean air for several hours before you judge its sensitivity. This is the most common reason a detector seems insensitive.
Manual §9.2Expected, and you do not have to wait for it.
Take the probe away into clean air, let it settle, and press ZERO there. That resets the baseline immediately — far faster than waiting for the sensor to clear by itself.
Manual §9.3, §9.7Then come back in slowly and approach the same point again. If the reading rises a second time, the leak is real.
The longer it sits in gas, the longer it takes to come back down.
A short press does nothing. Hold until the display lights and the buzzer beeps.
Charge fully before first use, and after a long period in storage.
Manual §8Do not leave the detector in a vehicle for long periods. The temperature and humidity swings damage the sensor.
Manual §11Shade the display with your free hand or with your body. The reading and the bar graph are easiest to read out of direct sunlight.
You do not have to watch the screen. The buzzer beeps faster as the concentration climbs, which is what you are actually following when you trace a leak.
Manual FAQ, §9.5