Situation.

I had a condenser fan failure: wasps built a mud nest in the housing when the D2 sat for a couple of weeks, fan apparently ran but couldn't spin/cool itself, brushes melted (literally) and armature warped from heat jamming against the stators (magnets), eventually the 40A fuse on the condenser fan relay blew.

Replaced the fan and the fuse. Now have power on the 5 pin in the relay socket, so can jumper pin 5-to-pin 3 and engage the fan.

However, the fan control circuit doesn't seem to engage under the likely conditions. There is power on Pin 1 (Pin 2?) but the the other Pin controlled by the ECM will not go to ground for either the AC or engine states.

It is my understanding that when the AC is on at the ATC, the ATC ECU "tells" the ECM to energize the condenser fan relay by taking Pin 2 (Pin 1?) to ground, thereby allowing current from the hot Pin 1 to energize the relay coil. Documentation (RAV and electrical diagrams) not clear as to whether this is all the time when the AC is operating or only when the air temp is greater than 82F and/or vehicle speed is less than 100kmph (60mph).

Likewise, when the coolant temperature gets above a certain level (95C?), the fan relay should also be energized by ECM.

I've created what I believe are both the appropriate AC and engine conditions, yet neither the AC nor the engine temp conditions seem to be causing the ECM to energize the coil in the condenser fan relay.

Anyone have thoughts on this?

Maybe I have a bad ECM -- or at least the transistor in the ECM that takes the condenser fan relay coil circuit to ground and allows the relay coil to energize?

How would someone troubleshoot this?

And if the ECM is in fact bad, is it a straight plug-and-play, i.e., can I just swap out one ECM with a known good one?

Or does the ECM need to be programmed/paired to the vehicle itself (which I am guessing requires a diagnostic tool that I certainly don't have)?



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I havent had this issue.

I would not believe that a melted fan could damage the ecu (isn’t that what the fuse is for - and it did pop as designed)

without looking at rave, I remember the temp trigger for the fan as 210f (it is in there just can’t look right now

if the ecu is the problem, seems like you’d have other issues too.

and yes it would have to be programmed to match

 

@austinlandroverbill Air conditioning is on or when your engine is above 212 degrees,

From the Rave

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 °C (82 °F) 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 °C (77 °F).

A manual diagnostic check includes a check of the sunlight sensor, and is initiated by pressing and holding the AUTO
switch and the air distribution switch, then turning the ignition switch from off to on. The audible warning sounds once
and the indications on the control panel display illuminate. FC is shown in the LH temperature window and the results
of the check are shown as a two digit fault code in the RH temperature window. If a fault is detected, the audible
warning sounds three times and the AUTO window on the display flashes on and off for 20 seconds. If more than one
fault is detected, the fault codes cycle in numerical order, at 1 Hz. The audible warning sounds as each fault code is
shown. In low light conditions, to avoid false sunlight sensor fault indications, the sunlight sensor should be illuminated
with a strong light source.

 

Thanks.

The cooling fan request is output if vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more.

The external air temp according to the ATC display has been 90-97 when I have turned the AC on: when the D2 is standing still, there's no signal from ECM to the relay to energize the relay coil (Pin 1 of the relay socket doesn't go to ground) and allow current to flow to the motor.

I also ran the ATC manual diagnostic check and the sunlight sensor initially failed (FCs 21 and 22 as I recall). However once I move the D2 so the sensor was in direct sunlight and ran the manual diagnostic, it passed (no fault codes).

Haven't gotten the engine coolant temp above 100C yet: when "hot" and external air temp in the 90-100F range, coolant temp seems to want to stay bet. 93 and 97.5C according the the datastream from my OBDII tool.

 

I can test mine later today it is supposed to hit the mid 30's

 

Ok, success (maybe).

I finally got the coolant temp over 100C and the fan runs: hurray:

So I now know that the ECM pin that controls the condenser fan relay is not bad -- huge relief.

However, not sure whether my ATC is functioning correctly as the wording of under what conditions the ATC sends a signal to to the ECM to engage the fan is still unclear.

Back to the language from the RAV

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 °C (82 °F) or more.

So it the fan suppose to engage:

when the vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more?

or

when the vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more AND the engine (coolant) temp exceeds exceeds some temp (100C)?

BTW, 2 questions related to this:

1. Can the backlight bulbs in the ATC be replaced (as a couple of mine are burned out)?

2. What is supposed to be the (coolant) operating temp range of the engine -- mins and maxes?

 

Alright, an update.

Looks like my ATC ECU might have been bad.

I picked one up used, installed it, and now the condenser fan runs whenever the AC is engaged -- and not just when the engine reached a particular temp (somewhere between 94 and 100C).

So after replacing a burned out condenser fan (lesson: if car sits for a while, check to make sure mud dawbers haven't built a nest in the electric fan), the engine fuse box (probably not needed) and the ATC ECU, it looks like my cooling system is fully functional.

Now I can turn to upgrading the thermostat.