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2009 Enclave Fan Runs All the Time

Mr. Michael J

By Mr. Michael J
in Ask A GM Technician

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Mr. Michael J New Member

Mr. Michael J

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The air conditioning went on my 2009 Enclave this summer and I decided not to have it fixed and continue to drive it until at least next spring.  Now the engine cooling fan is running on high full time.  My mechanic says that with zero pressure in the A/C system, the computer sends a signal to the fan to run all the time.  Now I am faced with either a $2,000 bill to fix the A/C or buying a new car before winter.  Can this be right?

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

I'd get a second opinion. Every time I've seen a cooling fan stuck on high, there was a communication fault with one or more modules, or a faulty ECM.

It's Tim Senior Enthusiast

It's Tim

Posted
Posted
1 hour ago, Mr. Michael J said:

The air conditioning went on my 2009 Enclave this summer and I decided not to have it fixed and continue to drive it until at least next spring.  Now the engine cooling fan is running on high full time.  My mechanic says that with zero pressure in the A/C system, the computer sends a signal to the fan to run all the time.  Now I am faced with either a $2,000 bill to fix the A/C or buying a new car before winter.  Can this be right?

Check the sensors, the vehicle isn't worth a $2,000.00 repair.

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

I would think that if the "computer" is seeing zero pressure in the A/C system there must be a sensor telling the computer there is zero psi.  If the sensor is a simple 2 wire sensor, unplug it and see what happens.  If it still runs, short the two pins together while it is still unplugged.  If it is a 3 wire plug, you will need to trick the connection to not report zero psi.  With that being said, it does not really make any sense to run the fan with zero psi in the system.  Is the clutch engaging on the compressor as well?  If it is, pull the plug on the sensor on the accumulator, that should stop the compressor from engaging, in turn making the fan stop.  The fan will still work if the engine overheats/gets hot.

Try checking for a fuse or relay that is marked Fan High Speed.  Don't know if they have their own relay or fuse, but it only costs time to check and see.

silveradosid Senior Enthusiast

silveradosid

Posted
Posted

you have a 3 wire pressure switch on the ac system, if you have no pressure the low pressure side of the switch is open and the high side is closed. when you have to high of pressure the low side open and so does the high side to command the fans on at high speed. you have either s faulty pressure switch or the wiring to the switch . an open circuit on the high pressure side will put the fans on all the time

mjm-1957 Enthusiast

mjm-1957

Posted
Posted

No freon in the system will not cause the cooling fans to run on high speed, more than likely a sensor is disconnected. Scan for trouble codes and go from there. When your mechanic was checking the system he may have left something disconnected.

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