"For Sweden" (rallybeetle)
10/22/2016 at 14:34 • Filed to: Maintenance, DIY
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"For Sweden" (rallybeetle)
10/22/2016 at 14:34 • Filed to: Maintenance, DIY | 0
| 9 |
The air conditioning in my S80 is out. I turn on the system, and the compressor clutch does not engage. It’s almost certainly a leak, but I want to check the wiring before buying a manifold gauge set. Below is the pertinent section of the wiring diagram.
The important components are...
2/22 Relay
8/3 Compressor
When I turn on the ignition without starting and jump terminals 3 and 5 on the relay, the clutch engages; that part works as it should. I also pulled the relay and verified it works.
With the car on and the air conditioning switch on, terminals 2 and 3 light up a test light. Terminal 1 does not.
I think this all points to the ECM not sending a signal to engage the clutch. Am I missing something?
McMike
> For Sweden
10/22/2016 at 14:48 |
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Low pressure switch? Where does that feed into the circuit?
Figure out how to jump/bypass the low pressure switch and see if you get voltage at relay terminal 1.
iSureWilll
> For Sweden
10/22/2016 at 14:53 |
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Looks like you’re correct. ECU not sending the signal to the relay to turn the switch on. McMike mentioned the next point to check, the low pressure switch. If the pressure in the AC system is too low the ECU won’t let the clutch engage. That is to save the compressor from chewing itself apart. Make sure you have good psi in the system and go from there.
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For Sweden
> McMike
10/22/2016 at 14:55 |
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That switch, 7/8, feeds directly to the ECM.
TheHondaBro
> For Sweden
10/22/2016 at 14:57 |
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This is a serious post coming from For Sweden, and there are no references to the proletariat. This is doing me a great confuse.
RutRut
> For Sweden
10/22/2016 at 15:01 |
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On the right track. ECM looks to be a low side driver (provides the ground), so something is telling the ECM not to engage. Does your vehicle use high and low switch, or a transducer to detect pressure?
ITA97, now with more Jag @ opposite-lock.com
> For Sweden
10/22/2016 at 17:17 |
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Jump the low pressure switch and briefly evaluate if everything then works normally. I would first momentarily crack the scrader valve on the low-side port, just to make sure you don’t have an empty system. Disconnect the switch and use a paper clip to jump the circuit. If you have an automatic climate control system, you may have to reset/clear the memory for it to engage the compressor after it senses a low pressure circuit error (even with the switch jumped).
RacinBob
> For Sweden
10/22/2016 at 17:20 |
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Another way to go at it is to remove one of the charging caps and expose the valve. Use a key or something to depress the center plunger for just a instant. If it is hissing with good pressure, the system has a good charge. If it barely hisses, you may have a slow leak so you might try recharging it. If you cannot get anything out, you have a flat system and it will probably leak out as fast as you put it in.....
Charging valve below.
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McMike
> For Sweden
10/23/2016 at 08:37 |
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Oh look, three wire pressure sensor. I think the return voltage of one of those needs to be a specific value. Don’t think you can jump one of those.
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McMike
> ITA97, now with more Jag @ opposite-lock.com
10/23/2016 at 08:41 |
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I was going to suggest the same thing, but he posted a diagram and it’s a 3 wire pressure switch. If you jump it, it will send back the incoming voltage from the ECM. What voltage does the ECM require to simulate a OK pressure reading?
I don’t know.