The AC fast cycles on and off.
I checked the pressure with a ‘topping off’ kit, and it seems good. I can see the switch through the grill but can’t find any instructions on accessing and replacing the pressure switch. It blows cold when on, and the relay is newly replaced, so I suspect the pressure switch might be faulty. Is there a built-in valve that allows unscrewing the switch without losing refrigerant? Any advice is appreciated.
You’ll need to recover the refrigerant before removing the pressure sensor.
A reasonably advanced scan tool can show what the sensor is doing.
Thanks, that helps. I read that most cars have a ‘presta valve’ feature allowing the pressure switch to be removed without losing refrigerant, which is economical and environmentally friendly.
I have a “CAN OBDII” scan tool for my 2005 Accord, but I haven’t tried it since I didn’t see anything related to the pressure switch in the code list. A more advanced scanner likely won’t show more since the 2005 Honda OBD port data doesn’t include pressure switch info, right?
Scanners from Autel and Foxwell provide factory Honda features at a reasonable price.
I found the manual for my OBDII scan tool, which lists 10 A/C codes. I scanned and found no error codes. The I/M checks include an A/C section, but my 2005 Honda shows “N/A,” meaning it doesn’t support an A/C monitor. Can I assume a more advanced scanner won’t find anything more? The A/C worked fine on a recent 30-minute drive in 85°F weather but often conks out and fast-cycles after a while.
I don’t think your scan tool is capable of reading the pressure switch. It should be a live data stream of the pressure.
If the AC runs for a short period and then starts short cycling it could be the pressure is too high because the condenser isn’t able to shed enough heat or the expansion valve in the evaporator is failing or icing up.
I conducted some research, and it appears that replacing the pressure switch is not too complicated. According to the articles I have read, if you’re replacing everything, you just unmount the switch, swap the wires and hoses onto the new part, and then remount it.
I had a similar issue with my AC where it would cycle on and off frequently. After checking the pressure and replacing the relay, I suspected the pressure switch might be the culprit. From my experience, replacing the pressure switch usually involves locating it on the AC line, and many systems have a built-in valve that lets you unscrew it without losing refrigerant. I found it helpful to consult the AC unit’s manual for specific instructions, as designs can vary. If you’re unsure, a professional HVAC technician can help with the replacement and ensure no refrigerant is lost during the process.