Hey guys... just another quick one for reference... My AC thermo fan isn't coming on with the AC meaning it isn't cooling properly... I have checked and there is no power going into it... what is the next step for finding where the power had been lost?
The AUX fan does not come on with the A/C except under near overheat situations. You can rewire it to come on with the A/C circuit, or if you have nistune you can change the parameters to make it come on with the A/C at all times (all temps and vehicle speeds), which is what I've done.
it should come on sooner than that to keep the pressure of the ac down? - i was under the impression that it should come on at near overheat, OR whenever the compressor is running... - the AC isn't performing up to standard unless im doing over 70km/h wihch i presume is due to airflow through the engine bay...
unfortunately... I've noticed the same thing about the zed aircon... its great when the car is moving, but in stop start traffic it does start to struggle.... Its fine if the car is shaded.... but if the car has been in the sun all day, and then you use the aircon in traffic, it takes an eternity to get cold.... My camry or mazda 626 on the other hand is much much better in the aircon department... Both my zeds have this quirk. The NA has been regassed and is working perfectly. The TT has not needed to be repaired or regassed at this stage. But they both function the same way.
Test the AUX fan by locating the Rad Fan relay in engine bay. Place a thick wire between the two female terminals as shown below. Then switch ignition key to ON (not start) The Aux fan should come on. If it does, it is working OK. The aux fan is controlled by the ECU to come on at various times, from memory in a TT it will only come on with AC if engine temps are 95deg+ or NA I think from memory is 100+. You are NA I notice. . If you have conzult/datascan, you can trick the ECU into thinking the temp is higher than actual, to test if the ECU turns the fan on. Here's the official way to test the fan from the service manual. But my simple way above will do the same job. Just remember to remove the wire before you finish.:zlove:
Even easier way to test the aux fan is to simply unplug the CTS. I use a variable resistor across the CTS connector to simulate temps, I can adjust temp from 30*C up to 140*C. Using the manual test in consult does not have the same effect as the ecu is already in diagnostic mode when ever consult is communicating. Not sure about ecutalk, datascan and other software.
Eric, are you referring to when Consult sometimes doesn't engage the aux fan when in the Consult solenoid test section? I've found on some TT's or NA's, consult won't engage the aux fan by clicking the fan button. Yet on others it works fine. But in either consult or datascan it will always work, when simulating an overheating engine temp by manually changing the engine temp setting. As far as being in diagnostic mode or not, I'm unsure if this means anything different? You are still intercepting the CTS input signal inside the ECU. For TT's I set it to between 96-100 with A/C on to test low-speed aux fan setting, and 105+ for high-speed. I like the variable resistor idea though. Clever!
I'll post up a screenshot when I get home. It's not difficult to work out though, Find the A/C section in the left hand column and then specify in the checkboxes what speed ranges you want the AUX fan to operate with A/C on and off Trouble with tricking the ECU into a higher temp is that the STD ECUs will start to richen mixtures above 95 degrees, thus reducing heat load on the engine but dropping power as a result.
If you have datascan, easiest way is to put in a setting of 95C (in active test) with A/C on and the fan should start. The actual setting is >91C and speed less than 40KM/Hr with A/C on. Nistune users can scroll to the bottom of the MISC settings and you will see the aux fan constants. I've set mine to run the fan at any temperature with A/C on at < 40KM/Hr
