Thread: air con pressure switch

The dual pressure switch has no involvment in the fan management, it is there to protect the compressor, opens to cut the compresor relay's feed below 2.3 and above 26 Bar the rest of the time is closed

What do you mean that the relay and fan test OK? that you activated it through tester and the fan kicked in?...did you see the fan actually working? , if your answer is yes, the first suspect is the ambient air temp sensor behind the front grille... do you get proper temp reading on the aircon display when you push the EXT button?...be aware that there are conditions to be met for that fan to kick in, first is that the outside temp to be above 28*C otherwise the management will not activate it

if you want to test the temp sensor properly blow on it warm air with a hair dryer while the aircon is on, then it must make the fan work if everything is OK

I tested the relay by removing it and powering it up with jumper cables used another set of jumpers from relay into the socket of relay this worked the fans as I had to replace the aircon condenser as the old one had o hole in it.


a few months earlier had to replace a hose as it had blown off as ferrule had split, only found the leak in the condenser when I went to get it regassed and the tech said the pressure went high and fans had not turned on.


yes the ext temp does work so will see what happens next week when I get the gas put in.

you did well your tests...it means the circuit and the fan are good, as long as the temp reading is good it means that the fan will work when it's supposed to, which means when you get a 28*C or greater reading on the display regardless of the refrigerant system's pressure

Also once you hit 100k's or more,and ambient is above 28degrees c,the fan will drop off.It will also drop off at 25 degrees no matter what the road speed.At 80k's or less with ambient at 28 or more fan is always on.

As others have said,the dual pressure switch turns the compressor off only.
Out at around 28psi low,or 465psi high.