KKRT Posted September 19, 2017 Share Posted September 19, 2017 Team mates, I have this annoying problem a few mechanics have not been able to help me resolve. My cooling fan shuts down for about 30-45 seconds and comes right back on. In effect, you hear the cooling fan running all the time. Engine temp stays around 180 degrees. I have also changed the fan switch sensor on the back of the engine (coolant reservoir) still no change, fan continues to run. Any suggestions out there? Quote Link to comment Share on other sites More sharing options...
tjc transport Posted September 19, 2017 Share Posted September 19, 2017 when my 05 did that, it was overcharged ac. i bled off a few ounces of refrigerant and the problem went away. i think the high side switch was weak and reading too high pressure. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
bbigrig Posted September 20, 2017 Share Posted September 20, 2017 If you have a Behr type fan clutch on tour ASET engine it has probably failed internally. This is not always the case, as there have been some wiring harness issues to the fan. On one Vision we had with a Behr fan clutch it use to fail every year and a half. Quote Link to comment Share on other sites More sharing options...
KKRT Posted September 21, 2017 Author Share Posted September 21, 2017 I have an ASET engine. How do you check for a faulty fan before doing an expensive replacement (buying a new one)? Quote Link to comment Share on other sites More sharing options...
Mackpro Posted September 26, 2017 Share Posted September 26, 2017 Is yours air operated or all electric like the one in this bulletin? Behr fan clutch AC engines.pdf Quote Link to comment Share on other sites More sharing options...
KKRT Posted September 29, 2017 Author Share Posted September 29, 2017 All electric. I put a new fan in the truck but I have the same problem: Fan continues to come on every 30 seconds even when AC is off. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted September 29, 2017 Share Posted September 29, 2017 Unplug the 3 connectors from the engine ECM and check for coolant or oil inside the connector. Quote Link to comment Share on other sites More sharing options...
Flat Work Posted October 1, 2017 Share Posted October 1, 2017 Heck, I turn my A/C on just to kick my fan on to keep the engine running cooler. But I run the city a lot. And spend quite a bit of time idling. I'm also really obsessive about coolant and oil temps. I wish it had an override switch to where you could elect to run it manually. Here's a question for the gurus- if I unplug the A/C compressor, will the fan still kick on if I turn the switch in the cab to the on position? Quote Link to comment Share on other sites More sharing options...
Mackpro Posted October 1, 2017 Share Posted October 1, 2017 On The ETECH or ASET engines , if you have a air fan clutch , you can add the factory fan over ride switch and have the dealer turn it in the software. On the ASET engines with the electric BEHR fan. There is no option for a fan over ride switch. However I have seen people take one of the wires going to the "green" AC pressure switch on the high side line ( not the one on the drier) cut it and run it in the cab and run it through a switch and back out to the pressure switch. This way you can break the circuit with the switch and turn the fan on as the ECM thinks the AC has high pressure. Plus it's still running through the high pressure switch so it will work a usual. This circuit is active whether the AC is on or off. 1 Quote Link to comment Share on other sites More sharing options...
KKRT Posted October 2, 2017 Author Share Posted October 2, 2017 Macpro, I unplugged and checked the 3 connectors for the engine ECU. None of them have oil or antifreeze in them. Could a bad ground cause this fan problem? Quote Link to comment Share on other sites More sharing options...
KKRT Posted October 6, 2017 Author Share Posted October 6, 2017 Teammates, I after lots of guessing and fan clutch replacement (expensive), it turned out to be a bad AC high pressure switch (picture - green switch). Fan works normal now, and only comes on when coolant gets hot. I appreciate the input from all. Quote Link to comment Share on other sites More sharing options...
Leo199107 Posted March 21, 2019 Share Posted March 21, 2019 Hello guys I had a bad fan clutch , and I replaced today ,but I went and tried to be a pro and installed an override fan switch . I hook up the hot (power wire) just before the fan solenoid valve and a ground from the frame . I by an accident let the ground and the hot wire touch each other ,and my fan is stuck running now I can’t get it to stop . I checked that hot wire for power with a test light and it doesn’t have power at it . I followed my checking with my light test tool , and I have power everywhere ( ac high and low pressure switches ) all have power except The coolant temperature sensor that attached to the over flow tank and the Engine fan solenoid valve don’t have power in the wires . WHERE IS THE RELAY fan solenoid valve wires ? If there is any ? Btw (I checked that 15 amps fuse for the fan clutch and it’s not blown ) so idk where would I find that relay for the solenoid valve , so I can get the fan to stop from running everytime the truck is on . Btw I have an AI460 2006 chn613 Mack (the green engine ) Quote Link to comment Share on other sites More sharing options...
Thors Mack Posted March 10, 2022 Share Posted March 10, 2022 Our 2018 CHU613fan came on and stayed on for quite some time, 150 miles, then a few miles from Mack shop, it turned off and had been working normally. we team drive. A/c dryer dirty? We’ve owned nearly 11months and take care of PM, what else could it be? Keeping it from simplest thing to not? No GOOD Mack shop near us! thanks Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted March 10, 2022 Share Posted March 10, 2022 Ac high pressure/coolant temp control fan operation. Ground by ecm. 1 Quote Link to comment Share on other sites More sharing options...
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