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79PSL3-2
This is an A/C fan override pressure switch designed for heavy-duty trucks using R134a refrigerant. It monitors refrigerant pressure in the A/C system and, when pressure rises above 270 psi (typically under high load or hot conditions), closes the circuit to engage the engine cooling fan, helping the condenser shed heat. The switch opens again when pressure drops to around 200 psi. A failing switch can cause erratic fan operation, A/C system shutdown, or engine overheating, making replacement essential when diagnostic pressure tests confirm malfunction.
Requires the correct 2-pin pigtail (often sold separately, e.g., Paccar 11-3162 or equivalent 1546). Ensure the A/C system is properly evacuated before replacement. Metric M10-1.25 fitting.
Part Number: 79PSL3-2
Fan AC Switch
Dealer: Knox Trailers
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