AC circuit
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AC circuit
I am trying to trouble shoot my AC electrical circuit. It appears I am not getting any voltage to the compressor clutch. Checked the low side and there is 45 PSI of pressure. The truck is 1989 F250 7.3 Diesel
Does anyone have a wiring diagram.
Thanks
Ken
Does anyone have a wiring diagram.
Thanks
Ken
Fleet Owner
Joined: Aug 2005
Posts: 23,666
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From: Easton,Ks
The low side should be about 85 to 95 psi. with a fully charged system and with the compressor not running.
You have a low charge but 45 PSI should be enough to turn on the compressor for a few seconds before it drops down below the cutoff pressure.
The low side should be about 40 to 45 PSI with the compressor running.
You have a low charge but 45 PSI should be enough to turn on the compressor for a few seconds before it drops down below the cutoff pressure.
The low side should be about 40 to 45 PSI with the compressor running.
Last edited by subford; Jun 18, 2006 at 08:16 PM.
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From: Virginia
I can't find a diagram, but I do not think there is much to it. There is a fuse that feeds the wire going to the switch on the ac controls in the cab. After that it goes right out to the low pressure switch and then to the compressor. There is a wire coming off that goes to the engine computer if you have an automatic, but it just tells the computer to bump the idle speed up a little bit.
Take the low pressure switch connector off the accumulator/dryer, and make a small jumper and jump the terminals in the connector while the engine is running, and see if the compressor will run.
If it won't make sure the fuses are good, and check to make sure with the ac control on, you have 12 volts on one side of the low pressure switch connector.
If you do not have 12 volts one one side of the connector, you may have a switch problem in the dash.
If you do have 12 volts on one side of the low pressure switch, and jumping the switch did not make the conpressor kick in, then you must have a problem with the clutch itself, or the wiring to the clutch. There should be a ground wiring hooked to the clutch from somewhere in the harness, with a diode in there too.
Take the low pressure switch connector off the accumulator/dryer, and make a small jumper and jump the terminals in the connector while the engine is running, and see if the compressor will run.
If it won't make sure the fuses are good, and check to make sure with the ac control on, you have 12 volts on one side of the low pressure switch connector.
If you do not have 12 volts one one side of the connector, you may have a switch problem in the dash.
If you do have 12 volts on one side of the low pressure switch, and jumping the switch did not make the conpressor kick in, then you must have a problem with the clutch itself, or the wiring to the clutch. There should be a ground wiring hooked to the clutch from somewhere in the harness, with a diode in there too.
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