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I recently purchased a 92 F150 2wd and the A/C doesn't work. When I turn the **** to A/C nothing happens. The pump doesn't engage and I only get warm air. How does one troubleshoot this problem? The fuse is good. I did notice that there's a broken vacuum line coming out of the firewall and then making a 180 degree bend back to some sort of diaphram sitting on top of what I think is the box that holds the heater core. This box is on the firewall just under the hood on the passenger side corner of the engine compartment. The vacuum line isn't broken apart. It is as though the bend created tiny cracks and over time the upper half of the bent portion of the hose crumbled off. When I touched it little pieces just fell off. Could a vacuum hose have something to do with it not working?
well first off fix the broken vaccum line then check to see that the AC system has a charge in it if it has a good charge try jumping the low pressure switch and see if it engauges the compresser if it does and blows cold air then the low pressure switch is probably bad
That hose probably goes to the damper for hot cold air control, or the fresh/recirc damper.
You have to get a refrigeration gauge. Does it have r-134 in it? There should be a sticker on the compressor or the hood.
The easiest way is to take the connector off the compressor clutch and connect 12v and ground to it. The clutch will click and it will run or stop the engine.
Did you check the fuses and relays? It is fused.