My condenser fan won’t turn on for some reason. Fan motor itself is okay, as well as the relay. If I connect +12v to the red/black wire of the pressure switch connector, it activates the relay and turns the condenser fan on. If I disconnect the pressure switch, the AC compressor will turn off. Is it a faulty pressure switch, or something else?
Condenser fan won’t turn on. Fan, fuse and relay all good. (1 Viewer)
- Thread starter HRTROB
- Start date
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It's either the pressure switch or the connector itself or wiring leading to or from it.
Check to see that you have 12v. coming into the connector (fan side of pigtail) and also your grounds. Trinary (pressure switch) do fail...but its not common. More likely the wiring or a bad connection.
Check to see that you have 12v. coming into the connector (fan side of pigtail) and also your grounds. Trinary (pressure switch) do fail...but its not common. More likely the wiring or a bad connection.
What is your high pressure side showing at its highest pressure (like on a hot day, at idle)?
The fan comes on when the high side reaches a certain pressure. How hot is the air in Philippines? ( I just checked and it is 27 C) If it is not so hot, the high side is working at a proper pressure and may not trigger the pressure switch to turn on the auxiliary fan.
- Thread starter
- #5
Compressor turns off as soon as I unplug the pressure switch. That means there is power and connections are good on the switch connector, right?
Unfortunately I don’t have a pressure gauge so I have no idea what the pressure is.
It gets pretty hot here during the day. Outside temp sensor showed 32C (90F) this afternoon. Fan won’t turn on even if the rear AC and cooler box are also on.
It means the power and connection are good to the COMPRESSOR portion of the switch. The circuit that goes to the fan is separate from that. That is why you need to check the connector and wiring to and from the fan.
The Trinary switch (pressure switch) is designed to complete and interrupt the fan circuit at specified pressures. So when your high side line sees approximately 220-225 psi the switch 'should' complete the circuit allowing power to the fan. Once the line pressure drops to approximately 180 psi the switch will open (interrupt) the circuit causing the fan to stop.
The pressure switch also has a High/Low feature that will prevent the compressor from running if pressures are below a certain point...or higher than a certain point. So....be aware that a Trinary Switch (necessary to operate a condenser fan) has a function not present in a simple Binary Switch (that only has high & low cut out capability).
Since your compressor will come on....we know that your refrigerant charge is sufficient to meet the minimum pressure for operation (approximately 30 psi). But we don't know if your system is correctly/fully charged and you didn't say IF the unit is cooling at the vents properly when operating?
IF the system is never reaching 220psi then even a properly functioning Trinary Switch will not call for the fan to come on.
If it were me....I would first probe the connector to insure you have 12vdc at the pins that require it and also your ground wires (that complete the circuit once the switch closes). Carefully check your wiring for breaks/corrosion/chaffing. If all that checks out then I would hook up a set of manifold gauges and check the system pressure. IF that is good then lastly...I would suspect the Trinary Switch itself.
- Thread starter
- #7
Do you have the wiring diagram for the AC? I believe the wiring to and from the fan is good, because when I applied +12V to the red/block wire of the pressure switch connector, it triggered the relay and turned the fan on. Cooling from the vents is okay, but it takes some time to cool on a hot day. Yesterday I noticed that the driver side vents cooled quicker than the passenger side. I think I may be low on refrigerant.
- Thread starter
- #8
Okay I had the refrigerant refilled. The fan turned on when the high side reached 260 psi
OK, so I believe I misunderstood what you initially did (testing). To be clear: You disconnected the harness to the pressure switch then applied 12vdc directly to the (hot) pin for the condenser fan (ground is already provided) and the fan activated?
IF so...then yes the circuit itself (wiring and connector) are good. That would leave only three possibilities.
1. The pressure switch is defective.
2. Your system is not charged with enough refrigerant to build high side pressure to 220-225 psi.
3. The outside temperature (ambient) was not hot enough to cause the corresponding pressure of the refrigerant to reach 220-225 psi.
You mentioned that you thought the ambient temp to be about 90°F. Although pressures will vary for a variety of reasons, we might expect a properly charged system to show a low side pressure of 30-35 psi and high side of 220-230 psi at that ambient temp. So IF your system is somewhat undercharged with refrigerant...that might be your trouble right there. You simply didn't have enough high side pressure to cause the switch to activate the fan.
The only way to know if that were true would be to put a set of manifold gauges on the system and check it. From your description of the temps (without benefit of a thermometer) it sounds like you might want to have the system checked for refrigerant charge....before moving forward with the troubleshooting.
^^^^^
Well....you posted as I was writing....
Glad you got it sorted out.
Well....you posted as I was writing....
Glad you got it sorted out.
