Here's the situation.

Some wasps built a mud nest inside the condenser fan housing.

The condenser motor apparently overheated, distended causing a short circuit and eventually burned up trying to run (we tore it apart to be sure that was the issue -- brushes were melted and fused, armature got warped out of round from the heat and wouldn't turn within the stator magnets without rubbing on them).

Replaced the motor with a VDO 9128(?); confirmed it was good by putting 12V, 10A power supply on it.

Tested the relay and it is good: it has those yellow Ford relays with blades numbered 1,2,3,5.

Blade 1 shows 14v with vehicle stationary the engine running, AC on and the ambient temperature reading 89 (according to the RAV at anything above 82 at the ambient temp sensor and the condenser fan relay should be energized).

In same state as above, Blade 2 shows 0.5V and 0.2ohms. As I understand it, Blade 1 is always energized, and Blade 2 is controlled by the ECU/BCU and is open when there is no condenser fan demand state, then connects to ground when the condenser fan is demanded, thereby closing the relay contact.

Blade 3 goes to the blue (hot) wire on the fan and shows continuity from Blade 3 to the connector (0.2ohms).

The Black wire at the fan connector shows continuity to ground (0.2ohms).

This leave Blade 5, which I assume supplies power to Blade 3 thru the relay when the condenser fan is demanded.

So there should be 12-14v on Blade 5 right?

There is 12-14v at the condenser fan 100A fuse, but nothing from the fuse to Blade 5.

I bought a used but known good engine fuse box and swapped them out but still no luck at getting 12-14v to Blade 5, which with Blade one powered and Blade 2 connected to ground, would otherwise allow current flow to Blade 3 and onto the condenser motor.

I am a bit at wits end here.

Am I right that Blade 5 should always be at 12-14V?

If so, anyone have any ideas why I don't have an voltage-current at that Blade.

 

Here's the diagram from the ETM. If doesn't help that they use the old convention of 30, 86, 86 & 87 and the relays use 1, 2, 3, & 5. In any event Pin 5 is always hot, yes. To run through the whole circuit, Pin 2 is hot when the ignition is on and the main relay is energized (and the inertia switch isn't tripped). Pin 1 is ground which is controlled by the ECU. In certain conditions (coolant temp or HVAC active) the ECU will provide ground to the fan relay which causes it to close and energize pin 3, which turns on the fan. According to this diagram, Pin 5 in the relay base is connected to the battery through Fuse 5 of the Engine Bay fusebox and also Fuseable Link 1 (however if this were bad you'd have a lot of other problems). Do you at least have continuity to the + terminal of the battery from pin 5 socket in the fusebox? This would tell you if there's a physical break in the connection.

 

Update:

I managed to get power to Blade5 of the relay socket. It was a blown fuse (Fuse 5 in engine compartment fuse box, 40). Don't know how I missed it (I was focused only on that 100A link fuse with the big fan stamped on it), but once I had a schematic (thanks Ahab), I figured that out at least. As Forest Gump says "Stupid is as Stupid Does".

So the fuse box was probably not bad after all.

Now when I jumper between Blades 5 and 3 with a paper clip (simulating an energized relay), voila, the fan runs, so all good there.

Tested relay yet again (just to be sure), and it works as it should, so I am back to the ECM, which looks like it is not putting out the signal it should.

I understand that the ECM uses either one or two sensors for input to determine whether to energize the condenser fan: the coolant temp sensor and the air temp sensor.

According to the data stream on my OBDII reader, with the engine running and the AC on, the coolant temp reached 96C and the ambient air 40C, and yet the ECM still did not send a signal to energize the relay (connect pins 5 and 3) to run the fan.

Where do I go next? Coolant temp sensor (it seems to be reading)? Air temp sensor (likewise seems to be reading)? ECM?

Again, when running and at the temp readings above, Blade 1 reads 12-14v continuous, while Blade 2 (the one controlled by the ECM and which the ECM is supposed to take to ground when conditions for the condenser fan are met)) reads 5V and no continuity (infinite resistance).

I don't see how the ECM could've gotten damaged by the wasp mud nest-to-motor burnout as it is not in that circuit at all.

 

From the RAV re. Engine Cooling Fan Control:-------------------------------------------------------------------------------------------
Engine cooling fan control

While the A/C system is on, operation of the electric engine cooling fan, to assist refrigerant condenser operation, is

determined by a combination of vehicle speed and external air temperature. When cooling fan operation is required,

the ATC ECU outputs a cooling fan request to the ECM, which then energises the cooling fan relay. The cooling fan

request is output if vehicle speed is 80 km/h or less while the external air temperature is 28 ÅãC (82 ÅãF) or more. The

request is cancelled, and the cooling fan switched off, if either the vehicle speed increases to 100 km/h, or the external

air temperature decreases to 25 ÅãC (77 ÅãF).
---------------------------------------------------------------------------------------------------

This is a little different operation than what the schematic shows?

And is the ATC the Automatic Temperature Control unit? And what is the ATC-ECU and how is it different from the ECM?

Could I have a bad ATC-ECU or ECM. How can I check? If one or both are bad, can they just be swapped out do they need to be programmed/paired to the vehicle?

 

ATC is the HVAC control panel. It is an ECU in the sense that it's an Electronic Control Unit for the HVAC system. The schematic I posted doesn't show it because you're not seeing the ATC <-> ECU circuit, only the ECU circuit. The ATC outputs a signal to the ECU telling it when to energize the condenser fan relay based on its desires, independent of what the main ECU is reading from the CTS, but its still the ECU that's switching the condenser fan relay on and off. I have a couple ATC spares if you want to try one however at this point I would drive the vehicle (assuming you haven't) and see what happens. There seem to be a lot of conditions that must be met for condenser fan operation and if you're driveway troubleshooting perhaps you just haven't hit the right combo. I will say that my condenser fan runs any time the AC is on, however I have no way of telling if it's shutting off over 62mph. ATC does not need to be paired to the vehicle so you can swap them in and out at will. That said, I've yet to see one go bad, which is probably why I have so many spares.

 

OK, a little more data.

In reading about the ATC ECU (I assume ATC = Automatic Temperature Control and ECU = electronic control unit (not engine control unit)), I forced the ATC ECU into the manual diagnostic test mode and got two FCs (fault codes): 21 and 22.21 Sunlight sensor, left output Open or short circuit No solar heating correction

22 Sunlight sensor, right output Open or short circuit No solar heating correction

Could this be the source of why I am not getting any signal to energize the condenser fan?

I thought there was just one sunlight sensor on the dash, not two?

 

Never mind, the manual diagnostic test can give a false positive if the sensors are not in direct sunlight during the test cycle.

 

ECU = electronic control unit, and in this case it's referencing the one that's used for Engine Management. The same Coolant Temp Sensor that tells the ECU how to adjust the fueling maps is the one that the ECU uses to energize the condenser fan relay.

Seems like you're getting closer. I'm not sure how to test the Sunlight sensors, if you check the ETM it should tell you if there are one or two. I'm guessing that it may be a dual channel sensor, one device with two outputs.

 

Ahab, going to start a new thread as I think maybe my ECM is bad -- or at least the output of the ECM that controls the condenser fan relay.

Before I do that, is replacing the ECM as plug-and-play affair or does the ECM require programming/pairing to the vehicle?

 

you can also test it by having coolant temp reach 210 i believe ,