Hi fellas, I had a mate come over last night so I could help him change some split Auto Trans lines that came out of the trans cooler at the front of the car, now I managed to rupture an A/C line and gas hissed out every where. He wasn't to worried as he said it didn't work anyway? Now we fix up the leaking trans lines and I send him on his way only to get a phone call from him about 15 mins later saying his thermos don't work? I said I have no idea how that can be linked to the A/C but he said the thermos were playing up a while back and the only way he could get them to run was to switch on the A/C, and now that the gas in the A/C has leaked out it doesn't work anymore?? Im not an expert on electrics by any means so I was hoping I could get some help form you lot. Given the thermos only use to work when the A/C was on would that just mean the sender is rooted? Id say that would be an easier fix then replacing the ruptured A/C line an re gassing it all.. Im off to work now so I'll check back in at about 4ish and see if I anyone has any ideas. 304-Runner
I can tell you that the thermo fan does run constantly when the A/C is switched on,it should also cut in when the car gets to a certain temp as you already know..Is the car getting up to the hot mark on the temp gauge,some temp gauges in these cars can read a fairly high temp before the thermo fan cuts in,like 3/4 on the temp gauge,sometimes even a bit higher.First up,Id be letting the car idle and let it get up to at least 3/4 on the temp gauge before deciding that the thermo fan doesnt cut in or work.If it doesnt work,then it could be the temperature sensor,theres 2 used on these cars,a single wire one for the temp gauge,and a multi wired one for the ECU to use,so the sensor that will need replaing will be the multi wired one as the ECU controls the cooling fan.
Cheers Brett, I'll have him pop over and see if the thermos do kick in. In saying that, I actually wondered what made my mate so sure they didnt work, after all this is a bloke that said his car "wasnt that long over due for a service, its only been 40,000k's?"
Ok so we had the car in the Garage and had it running for a bit. The temp went up well over 3/4 and the fan didnt engage. I pulled the sender out (I think its the one with two pins) and put it in hot water and tested it with a ohmmeter and got nothing? So im assuming the sender is rooted?
Id replace that temp sensor and see how it goes then.When the temp sensor is immersed in ice water,you should get an ohmmeter reading of 6000 ohms.And in water thats 100 degrees C (boiling) ,it shoud read 190 ohms.It could also be worth checking the cooling fan relay under the bonnet in the fuse box,just swap it over for one there thats the same type,but if the cooling fan was working before when the A/C was on,then its probably not the relay.
Ok, so we had another shot a fixing the fans last night and we replaced the temp sensor (2 pin plug) and still nothing. We then switched over the blower relay to see if that was the issue and got nothing. So I thought maybe the fan is shagged and I unplugged it and tested the loom side of the plug with test light and it was fine, so I hooked up power from the battery to the fan side of the plug and she went? I then decided to earth out the test light at one end and place the other end (spike)into the possessive(+) part of the loom plug and stated the car assuming the test light would turn on when the thermos are meant to engage but still nothing? Reading another post yesterday I noticed a comment about the ECU being a possible cause? But whats bugging us most of all is it never worked in the first place but did when the A/C was switched on, and after I ruptured the A/C line it doesn't work at all? I know its hard to diagnose and electrical problem in a forum thread but any more ideas would be a massive help.
Because it worked with the A/C on the PCM must be capable of switching the fan on, and the fan, fan switched and switching circuits must be OK. It comes down to the PCM not "deciding" to switch the fan on. A faulty coolant temp. sensor would cause that but as you have replaced it we need to look a bit deeper. Is there ~5 Volts on the yellow (I think) wire to the CTS? If you check the voltage across the two CTS wires that will also check the earth. If you want to dummy the CTS signal, a ~20 ohm 1/4W resistor (to avoid a short - I don't think it's an issue but better to be safe) and a 10K ohm variable resistor in place of the CTS across the terminals will allow you to vary the voltage on the CTS circuit to the PCM. That should allow you to switch the fan on and off via the PCM, by varying the resistance across the CTS terminals, if it (the PCM) is working correctly. You could use fixed value resistors instead of the variable one: 190 ohms is ~100C and the fan should switch on at 104C i.e. just less than the 190 ohms, say 100 ohms? ~1.5V at the PCM should switch the fan on. It is possibly the CTS circuit in the PCM has failed as there is a resistor in the PCM that is bypassed (shorted around ) at a certain temp - ~50C - and if the PCM thinks that is being bypassed but it's not the temp. will be seen as lower than it is. To get an operating fan until it is fixed you could disconnect the A/C clutch - so the A/C compressor doesn't run without lubrication (no gas) - and short the low pressure switch on the A/C receiver drier (black or silver cylinder on the strut tower) then use the A/C to switch the fan. Altenatively, look at the "How To" on switching the cooling fan on VN (VR works the same way).
