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fixing Idle up vacuum relay


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fixing Idle up vacuum relay (DIY)

(This is only relevant for older vehicles which does not have ECU or can drive through an EMP Attack :) )

When the AC is turned on the engine RPM should raise a bit to cater for the load it gets. To do so a vacuum line coming from alternator is connected to a mechanical suction unit (idle up switch). It pulls the accelerator cable so that the RPM increases. When AC compressor turns off the electrical relay valve cut off the vacuum suction to get the engine back to it's normal idle RPM.
The guy who fixed the Idle up switch to my jeep has forgotten the relay. So it always gave a high RPM at idle. I had to fix the cut off relay for that. Below is the pics of those two units. 




Pull Switch

Happy DIY project if you own an oldie with dual AC :)



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