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roybelding, Shop Foreman Freightliner trucks
Category: Medium and Heavy Trucks
Satisfied Customers: 5868
Experience:  Shop Froeman for Freightliner Trucks
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I have a 99 Freightliner CENTURY, vin XLA02952, a/c compressor

Customer Question

I have a 99 Freightliner CENTURY, vin XLA02952, a/c compressor engages very intermittently.
Submitted: 2 years ago.
Category: Medium and Heavy Trucks
Expert:  roybelding replied 2 years ago.
good evening my name is ***** ***** I will assist
the most common issue is the connectors at the binary switch and the pressure switch. the terminals spread and make for bad connections.
Customer: replied 2 years ago.
OK. I am now on a real keyboard. I had already checked those switches and connectors (both on the a/c lines below the evap housing. Just to be sure i checked again. 14V on one pin of both, and shorting them with a jumper wire did not engage the compressor.To be clear, this unit was cooling fine, then on the last trip out it quit for two days on the way back home. When I met the driver to bring it to my shop, it started working. I thought it was the power wire connecting the front fan switch to the selector control (has a/c switch built in), when I disturbed the connectors 2-3 times and it came on. All this while fixing up a bunch of other faults in both the front and bunk fan wiring. Mostly missing or bad circuit breakers and relays. I finally got all fan controls working how they should.I went back to put new terminals on the fan switch wires, and the fan switch broke apart (brittle, old). Today I just installed a new fan switch, which came with an "upgrade" modular connector as well. Fan function is fine again. 14V from the fan switch to the selector. 14V out when an a/c mode is selected. I also tested the thermo switch on the inside of the evap case under the dash panel. 14V through it.The compressor wiring follows an engine harness around the left side of the engine and disappears up above the starter. I would like to know where it is fed from inside the cab. A wiring diagram showing the compressor circuits would be helpful. The front fuse panel has no a/c compressor relay labeled. Only a circuit breaker. I switched with a known good one, no go. The bunk fuse panel only has three relays, an hvac, fan low, and fan hi. All three of those are new, and all circuit breakers are installed and working. Unless there is another panel, or an odd relay hidden somewhere, I am at a loss. Trying to figure out where the compressor power comes from inside the cab.I have quit for the night and will be back at it in the morning. Hopefully you will have a chance to review this latest report and respond by then. Thanks.
Expert:  roybelding replied 2 years ago.
ok, I need the last 6 of your vin
Customer: replied 2 years ago.
It was posted in the title. XLA02952
Expert:  roybelding replied 2 years ago.
sorry. missed that. looking up the diagram

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