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2006 peterbilt, Cat c-15 Acert. The engine fan comes on and…

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2006 peterbilt, Cat c-15 Acert. The...
2006 peterbilt, Cat c-15 Acert.
The engine fan comes on and off constantly so I've gotten the habit of just turning it on manually.
After a while , Sometimes 2 hours sometimes all day, the engine will suddenly derate.
Turn the manual fan switch to off and power comes back Immediately.
Submitted: 1 year ago.Category: Medium and Heavy Trucks
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Answered in 5 minutes by:
9/9/2021
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago
Nich1019
Nich1019, Cummins/Caterpillar Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3,268
Experience: Expert
Verified

Good morning and welcome to JustAnswer! I'm Nick and I'll be helping you out today. There are a few reasons that the fan may be cycling too much. The most common reason is a poor connection at the a/c fan override switch that's mounted in the a/c line between the compressor and condenser. This shouldn't cause a derate though. Do you have any fault codes? If there's an issue with the coolant temperature sensor the ECM will automatically turn the fan on.

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Customer reply replied 1 year ago
No check engine light, temp is 190
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

Ok, with the key on and engine off, wiggle the connection at the a/c override switch. See if you can get the fan to engage and disengage. It should be released with the key on and engine off. Make sure you have plenty of air pressure though.

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Customer reply replied 1 year ago
A/C over ride switch?
Where's that?
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

It's a pressure sensor that's mounted in the a/c line between the compressor and condenser. It's usually orange in color and has 2 wires connected. Follow the a/c lines from in front of the radiator to the a/c compressor.

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Customer reply replied 1 year ago
I'm driving but will try when I stop...
What am I looking for when I without the switch?
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

If the problem is there you'll hear the fan solenoid cycling and you'll see the fan hub move to engage and disengage.

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Customer reply replied 1 year ago
the problem will be the connection?
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

Either the pins are spread inside the connector or one of the wired is broken inside of the insulation and you can't tell just by looking at it. That's the most common reason.

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Customer reply replied 1 year ago
if wiggling the connection doesn't change anything it's probably the censor?
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

It's a possibility yes. If you suspect that it's the sensor, install a jumper wire between the two pins. The fan should stay off at that point.

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Customer reply replied 1 year ago
I'll try all this.
Thank you
Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

No problem. Sounds good, let me know what you find.

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Technician: Nich1019, Cummins/Caterpillar Technician replied 1 year ago

Good afternoon. Let me know if you need any further assistance. Thank you.

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