2006 / GX470

Air Conditioning condenser fan (CDS fan) doesn't turn/spin when AC is ON.

Question #1 - CDS fan must be always ON when AC is ON?
Question #2 - If the answer to the Question#1 is false, then when it turns ON?

Preface:
- Air Conditioning works fine, checked for leaks, refrigerant is added, pressure is OK, blows cold air both front/rear;
- CDS fan is fine, spins, checked by connecting 12V / Ground of battery;
- Pressure switch is OK, but we do not care about it (see below);
- Condenser fan (CDS fan) and compressor Magnetic clutch (MG CLT) relays are fine, checked.
- Fuse 20A CDS FAN, checked and OK;

Now please see the diagram:
- I have shortened pressure switch pins for testing purposes, in order to exclude its influence in CDS fan switching;
- When compressor turns ON, 12V on CDS Fan relay PIN1 against battery ground, PIN2 - 0V against battery ground - CDS fan DOESN'T SPIN.
You would think there is cut somewhere between CDS Fan relay PIN2 and ground, no I grounded it using extra cable directly, but fan still DOESN'T SPIN.
- It spins only when I manually shorten CDS Fan relay PIN5 and PIN3, but this is obvious...

Please, help to understand what is the problem and how it works!

 

If you briefly apply 12v to CDS Fan Relay pin 1, what happens?
If you briefly ground CDS Fan Relay pin 2, what happens?

Chip H.

 

Have not tried that combination yet...
Tomorrow will play with A/C ambient temperature sensor too... with cigarette lighter
I think A/C amplifier (ECU) decides when to switch it on based on 2 factors: temperature and pressure...

P.S.
1 year ago non-Toyota "refrigerant add" service guy told me that this is not normal, CDS fan should spin when compressor kicks on...

I went then to Toyota service, where official trained guy checked the fan the following way - he forced to stop by hand BIG engine fan, thus making some overheating and asked to start the car - in a few seconds engine started CDS fan has also started spinning - he said all is fine... the system is designed like that... CDS fan is controlled by refrigerant pressure (switch) and temperature...

Yesterday another non-Toyota "refrigerant add" guy told me - no this is not true, it should spin...

So, to whom we trust?

You all know noticeable A/C performance drop when car is in idle and not moving, that is why I have doubts

 

Update
=========
Done... works! This morning I have disconnected ambient temperature sensor (thermistor) and shortened connector with 350 Ohm resistor, which is equivalent of highest ambient temperature according to the given table from repair manual 60°C (140°F).

Then started engine with all widows opened and A/C front/rear at maximum - in a 30 sec condenser fan started spinning at idle.

Then checked the sensor (thermistor) with multimeter, it is also OK, connected back and fan still spins, since engine area got hot after 10 minutes of working.

So, nothing is wrong with the A/C system, it is designed like that, A/C amplifier (ECU) decides when to switch it on, based on 2 factors: temperature and pressure...

 

Trust the wiring diagram. MG CLT relay is controlled by the ECU, and downstream from that is the CDS FAN relay, controlled by the pressure switch. So it needs both to turn on.

Glad you confirmed it is working as designed.

Chip H.