Freightliner century class engine fan stays on all the time. When ignition is turned on, the screen in dash will show active fault. " AC Controller No Response 190 s 270 7 ". The ac on this truck does not work ( leak some where in ac condensor ). Any guess what might be causing this ? help is appericiated in advance. Thanks...

 

The engine fan will only stay on for a few reasons. Mosf of the time the fan clutch solenoid is bad. It is an electric solenoid that turns the fan on and off. You can find it by following the air line that comes from the fan clutch hub. In you case, it may be the A/C high or low pressure switch since you are getting an A/C trouble code. There should be a high pressure switch and a low pressuer switch on the A/C lines. Usually the problem is one of these things. Hope this helps.

 

Might be a short in the switch itself, always in the on position, even when it is in the off. I am not certain that would explain the code fault though.

 

rockymtnprodriver, is this the switch in the cab, (which is used to turn ac on and off ) are you pointing towards.

 

No, it is in the engine compartment, it is a sensor.

 

A bad fan clutch solenoid is usually the first thing to look for but could be several things. Loss of air to it, the engine temp sensor sending a bad signal to the engine ecm or the engine ecm interpreting the signal wrong, or the engine ecm receiving or thinks it's receiving a signal from the a/c high pressure switch. Could even be as simple as a bad relay.

Since you say you have an a/c fault code it could very well be associated with that. If you have anyone look at it be sure to mention the a/c fault. Depending on the engine they should be able to connect to the engine ecm and turn off the a/c input to see if the problem goes away. If it does you can leave it that way until you get the a/c repaired, just remember to have it turned back on in the ecm when the repairs or done or it will cause more problems when you start using the a/c.

 

The system is designed "FAIL-SAFE". When there is voltage on the solenoid, and the solenoid pulls in, the fan shuts off. Since it stays on all the time, I would first try turning off all fans, in the bunk, and on the dash. Without the fans on, the A/C will not operate, and the fan should shut off if that's the problem. However, if it does not, I would use a volt-meter and check for voltage at the plug to the solenoid. If you do have voltage at the plug, and the solenoid is not pulling in, I'd go for the solenoid. If the fan shuts off when you turn off both blowers inside, it's going to be an A/C problem.

 

fan solenoid probably cheapest option.....only takes 5min to replace and i paid $99 dollars for the part at the TA

 

I would call my dealer and ask for a fault code description. it's possible that the a/c fault is causing a loss of head pressure signal, which might keep the fan on... even if the a/c system is turned off. Or, the a/c hp switch could be bad... keeping the fan on. or, wiring for the switch... if that circuit opens, the fan stays on.

Or, the fan solenoid could be bad... or its ground... or live. Air supply to the solenoid? Engine temp input? Oil temp input? in some, even ambient air input can turn on the fan... dash override switch bypasses fan controls, it could be bad. maybe the fan clutch is seized on... is it a Kysor?

Does the fan spin free when the key switch is off? ...how about when the key is on (engine not running)?

 

....or maybe the fan override switch is in the override position and nobody is noticing.

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