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Join Date: Sep 2002
Location: Cedar Falls, IA
Posts: 212
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Help AC high pressure switch wiring
Thanks for all the help from everyone on my recent AC update (new barrier hoses and static underbelly condenser).
The only problem left to solve is wiring the high pressure switch that I got from AC source (thanks Jim Sims for the Info). Problem. The switch cuts in between 315 and 225 psi, i.e. at that pressure there is continuity between the leads. At lower pressures and at pressures between 398 and 405 psi the switch cuts out, i.e. there is no continuity. The drawing seems to show the switch wired in series with the AC compressor clutch coil. But that doesn't make sense because unless there is sufficient pressure you can't complete the circuit to the clutch. What am I missing here? Guy Chiattello 82SC Black Coupe |
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06-06-2003, 04:23 PM
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[B]"The switch cuts in between 315 and 225 psi, i.e. at that pressure there is continuity between the leads.[B]
Is that a typo? Should it be between 115 and 225? The switch should be wired in series with the compressor clutch. You have a combination switch that cuts out at low pressure and cut out at high pressure. You want to cut out the compressor at low pressure in the event that you are low on freon and could ruin the compressor by running with a low condition. You also want to cut out at high pressure so you don't pop a line or the condensor or compressor. There should be sufficient pressure on the high side of the system to allow the compressor to kick on when you turn on the ac. |
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06-06-2003, 05:15 PM
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Join Date: Jul 2002
Location: Southern California
Posts: 5,067
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Guy: I'm going from memory, but I'll check at home tonight and revise this if I'm wrong.
When I put the pressure switch on my system during the upgrade, the switch itself went basically in series with one of the hoses. So, when the pressure in the hose got abnormal, it activated the switch, and the switch shut down the compressor. The electrical portion of the switch is wired between the hot lead coming out of the car's electrical system that controls the compressor, and the DC input of the compressor. When the switch activates/opens due to abnormal pressure, it breaks the continuity of the 12 volt DC line, and the compressor shuts down. When the pressure returns to normal, the switch closes and the compressor kicks in again. I hope this information is helpful to you. I'm going to send you an e-mail with some questions about the static condenser. Good luck!
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1984 Targa Last edited by scottb; 06-06-2003 at 05:22 PM.. |
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06-06-2003, 05:18 PM
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Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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Guy, How many leads does the switch have? The low pressure cut out value (225 psi) you quote is too high. There are some "triplex" switches that at a certain intermediate pressures close a set of contacts to run an auxilliary fan to cool the condenser (like when one is stuck in traffic and not moving). If there is only one set of wires the switch may be defective. Jim
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06-06-2003, 05:29 PM
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Join Date: Sep 2002
Location: Cedar Falls, IA
Posts: 212
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The installation sheet says the switch cuts in at 315-325. Perhaps the sheet has a typo. I will check the system and see if I have continuity now that the system has been recharged.
Guy Chiattello |
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06-07-2003, 09:33 AM
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Location: Southern California
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Guy: You have mail.
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1984 Targa |
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06-07-2003, 09:36 AM
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Join Date: Sep 2002
Location: Cedar Falls, IA
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I got it working! I think what happened is I didn't realize that I hac a leak and lost all of the 134a so proceeded to check the continuity on the switch. But with no pressure it was opened. So after I found the leake and recharged the system, I checked the pressure valve and it had continuity.
Thanks again for the help. Guy Chiattello 82SC Black Coupe |
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06-07-2003, 05:48 PM
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