Ac compressor isn’t getting power. Both white wires from the AC switch inside the cab to the AC relay are hot. I’m not sure that both are supposed to be hot like that..anyone know? I’ve swapped relays, still nothing. Fuses are fine. I’ve jumped the low and high pressure switches and it does nothing. Back story- a week ago compressor didn’t come on for about the first hour of operation then worked rest of day. Second day same thing, 1 hr or so. Third day it never came on and hasn’t since. Freon pressure etc checks out to be fine. Any ideas?
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‘17 Cat 299d2
- Thread starter Kendall R
- Start date
BigWrench55
Senior Member
Check resistance on the clutch and then post the results along with your serial number. The year it was made is of no consequence.
BigWrench55
Senior Member
I believe that the power comes out of the pressure switch. Check for continuity from the compressor to the pressure switch. You probably have a broken wire.
power isn’t ever leaving the AC relay. Am I able to check resistance without Compressor having power? I guess I just need to read up on how to check out resistance. Diagnosing electric components isn’t my strong suite. Thanks for the info
Serial is DX201868
Im not so sure that they do if I’m interpreting this schematic correctly. High chance I’m not.. pg 11 top right corner has the AC components/switches
Nige
Senior Member
Here's a thought. If both sides of the A/C compressor clutch relay coil (I'm assuming wires 520 WH & C510 WH) are "energized", what's the chance that the two wires actually have the same 12v in them, that it's the operating signal from the controls, and that the relay is not pulling in for some reason..?
Is there any way to check the voltage between Wire A510 Orange and machine frame ground.? I guess it should be 12v.
If A510 does indeed have 12v then jumpering it to E554 Pink should activate the compressor clutch and prove that the relay is not pulling in.
Is there any way to check the voltage between Wire A510 Orange and machine frame ground.? I guess it should be 12v.
If A510 does indeed have 12v then jumpering it to E554 Pink should activate the compressor clutch and prove that the relay is not pulling in.
Yeah that would make sense if both white wires are signals wires. They are hot when AC switch is on in the cab and go off when switch is off. I need to try to find where the orange wire goes to on the cab side/under the cab and see why it’s not getting power to tell the pink wire to come on. I’ve swapped relays with one on the machine and no change(same relay part number) I guess it could be bad too but I trusted it wasn’t. And the pink wire coming from CONN 1 goes to the high pressure switch isn’t hot, seems like maybe it should be..I don’t know tho