96 a/c blowing hot...how to check fuse? Just a dummy here
stinkycat
07-30-2006, 06:28 PM
I went to get freon put in and the Jiffy Lube guy (yeah, I know) tells me my compressor is broken. I just had a transmission and water pump put in and I have had a few myriad problems stemming from this repair...so I went to check the fuse first, before I go spending anymore $$$ on this. I get the fuse out and I know I am not a repair person, but a fuse is simple enough...so I thought.
How do you know if it is a broken fuse if you can't see the filament? It is a square grey plastic box.
And if I just want to go get another one, what on earth do I call it so the teenagers working at the parts place know what I am talking about? I don't want them handing me the standart fuse replacement kit that you can get at wal-mart.
Also, the transmission wasn't doing so great and I took it back and they told me it was just a switch that needed replacing. Is the switch that controls the automatic transmission near anything that controls the a/c? Does the a/c have a switch?
How do you know if it is a broken fuse if you can't see the filament? It is a square grey plastic box.
And if I just want to go get another one, what on earth do I call it so the teenagers working at the parts place know what I am talking about? I don't want them handing me the standart fuse replacement kit that you can get at wal-mart.
Also, the transmission wasn't doing so great and I took it back and they told me it was just a switch that needed replacing. Is the switch that controls the automatic transmission near anything that controls the a/c? Does the a/c have a switch?
Blue Bowtie
07-30-2006, 09:08 PM
Is the compressor clutch cycling? Can you see the compressor turn or hear the compressor clutch engage when you turn on the A/C? I'm guessing the answer is "No."
The problem may be a fuse, or may be something else. Diagnosis will be a lot easier with a voltmeter, or at least a 12V test lamp. Given that you can get a cheap multimeter for less than $20, and it can be used for so many things, it is almost as necessasry as a screwdriver any more.
Checking the fuse is relatively easy with a voltmeter, ohmmeter, or test lamp. With a voltmeter or test lamp, simply probe each of the small test hole on top of the fuse while it is plugged in place and with the A/C circuit turned on. Both holes should indicate voltage. If only one does, the fuse is blown. If neither do, you have no power to the fuse. To test with an ohmmeter, remove the fuse and check the resistance between the two spade connectors. There should be 0 (zero) ohms or something relatively close. Infinite or high resistance indicates a blown fuse. All you would have to ask for at the parts counter is a "fuse" in the corect ampere rating.
Make sure the electrical connector to the compressor clutch is connected. It is a two-wire connector whose wires emerge from the loom at the front of the engine, down low along the oil pan rail and near the starter and oil filter. Also check the high pressure cutout switch connector on the back (right side as you view it) of the compressor. It is a single wire connector in the same wire loom. I've seen these taken off or knocked off during other service work (such as the water pump replacement). (I've also seen them intentionally disconnected after a water pump has failed, and the compressor clutch becomes contaminated with coolant to the point where is slips and smokes. I got my daughter's Lumina that way - They agreed to knock off $500 if they didn't have to replace the "bad compressor" and recharge it. I cleaned the clutch, adjusted the gap/springs, plugged it in, and it's been fine ever since.) If both connectors are in place, turn off the engine, turn the ignition back to RUN without starting the engine, and turn the A/C controls to cool. Test for voltage at the clutch connector. If there is voltage, the clutch should engage, or it may have failed. You can test the resistance of the clutch coil to determine that. If there is no voltage, turn off the ignition and proceed.
If the compressor conneectors are both in their proper places and the compressor clutch is not engaging, the problem may also be a low pressure cutout switch that is either disconnected or open due to a lack of system pressure (lost charge). You can test this relatively easily. The switch is located in the low pressure refrigerant line near the accumulator. The accumulator is on the lower right front corner of the engine bay, right along the subframe rail. Remove the connector from the cutout switch, insert a jumper wire into the connector to effectively short the two connections, then turn on the ignition and A/C controls again. If the compressor clutch operates, the switch has either failed or the system has lost almost all refrigerant and pressure. If the compressor clutch does not operate with the jumper in place, test each wire in the conneector for voltage to a good chassis or engine ground. One of them should have 12-14V. If not, either that fuse you checked is no longer good, or you have a switch problem in the dash mounted A/C controls.
Good luck with it.
The problem may be a fuse, or may be something else. Diagnosis will be a lot easier with a voltmeter, or at least a 12V test lamp. Given that you can get a cheap multimeter for less than $20, and it can be used for so many things, it is almost as necessasry as a screwdriver any more.
Checking the fuse is relatively easy with a voltmeter, ohmmeter, or test lamp. With a voltmeter or test lamp, simply probe each of the small test hole on top of the fuse while it is plugged in place and with the A/C circuit turned on. Both holes should indicate voltage. If only one does, the fuse is blown. If neither do, you have no power to the fuse. To test with an ohmmeter, remove the fuse and check the resistance between the two spade connectors. There should be 0 (zero) ohms or something relatively close. Infinite or high resistance indicates a blown fuse. All you would have to ask for at the parts counter is a "fuse" in the corect ampere rating.
Make sure the electrical connector to the compressor clutch is connected. It is a two-wire connector whose wires emerge from the loom at the front of the engine, down low along the oil pan rail and near the starter and oil filter. Also check the high pressure cutout switch connector on the back (right side as you view it) of the compressor. It is a single wire connector in the same wire loom. I've seen these taken off or knocked off during other service work (such as the water pump replacement). (I've also seen them intentionally disconnected after a water pump has failed, and the compressor clutch becomes contaminated with coolant to the point where is slips and smokes. I got my daughter's Lumina that way - They agreed to knock off $500 if they didn't have to replace the "bad compressor" and recharge it. I cleaned the clutch, adjusted the gap/springs, plugged it in, and it's been fine ever since.) If both connectors are in place, turn off the engine, turn the ignition back to RUN without starting the engine, and turn the A/C controls to cool. Test for voltage at the clutch connector. If there is voltage, the clutch should engage, or it may have failed. You can test the resistance of the clutch coil to determine that. If there is no voltage, turn off the ignition and proceed.
If the compressor conneectors are both in their proper places and the compressor clutch is not engaging, the problem may also be a low pressure cutout switch that is either disconnected or open due to a lack of system pressure (lost charge). You can test this relatively easily. The switch is located in the low pressure refrigerant line near the accumulator. The accumulator is on the lower right front corner of the engine bay, right along the subframe rail. Remove the connector from the cutout switch, insert a jumper wire into the connector to effectively short the two connections, then turn on the ignition and A/C controls again. If the compressor clutch operates, the switch has either failed or the system has lost almost all refrigerant and pressure. If the compressor clutch does not operate with the jumper in place, test each wire in the conneector for voltage to a good chassis or engine ground. One of them should have 12-14V. If not, either that fuse you checked is no longer good, or you have a switch problem in the dash mounted A/C controls.
Good luck with it.
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