Scorpio A/C Troubleshooting

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dimswits
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Re: Scorpio A/C Troubleshooting

Post by dimswits »

john keefe wrote: Wed Aug 03, 2022 9:44 pm Anyway, I've got a fully charged A/C system, but almost no cooling. 105psi on the high side, 100 on the low pressure side. Compressor sounds like its knocking, and never made that noise before. Manuals says it could be the 3-way expansion valve, but I have no way to testing w/o evacuating the whole system. It has a Rapido expansion tank sitting in front of the evaporator & fan.
Your compressor is not working at all. Those are static pressures of R134a at about 88-90 degrees ambient temperature. You have no cooling because the refrigerant is not circulating and the refrigeration process simply isn't happening.

Are you sure the clutch is engaging and the compressor is spinning?

The Scorpio uses the Nippondenso 10P15E compressor. "E" means "ear mount." The innards are exactly the same as the more common 10P15C ("C" for "case mount"). You should be able to get this sorted but you will need an evac and recharge.
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dimswits
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Re: Scorpio A/C Troubleshooting

Post by dimswits »

john keefe wrote: Fri Aug 05, 2022 12:25 pm Thanks guys. Ed, agreed (at least from what I read in the shop manual) that the expansion valve is likely the culprit, which could also be causing the compressor to knock. I'll have to check into how to evac the system (probably just find a shop).
You've misinterpreted your results. In the terminology of the shop manual on page 36-32-7, your low pressure reading is too high and your high pressure reading is too low. Possible cause: "Internal leak in compressor." This assumes the compressor is indeed spinning. If it isn't, your clutch or the wiring to it could have failed.

If your expansion valve were stuck even wide full open you would still have some movement of the refrigerant and you would see a greater pressure differential on the gauges.
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Re: Scorpio A/C Troubleshooting

Post by john keefe »

Ah, OK. Thanks Guys. One more thing to consider. In the middle of building an hydraulic e-brake for the 5.0LXR, so after that gets done and everything checked in panic stops... A little complicated because I'm trying to route the lines up to a f/r brake bias valve, but still be able to close it up with the stock arm rest, et al.
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Re: Scorpio A/C Troubleshooting

Post by Ed Lijewski »

I've been intrigued by John's high low side and low high side systen pressures and occasionally searched written and video mention of that condition but only today found these videos that directly consider it:

https://youtu.be/hILv3oOTWS8

https://youtu.be/8_lueV1Sp_E

YMMV
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Re: Scorpio A/C Troubleshooting

Post by john keefe »

Thanks Ed. Hope my AC problems aren't keeping you up at night looking for solutions. :) Only viewed both briefly, so I'm gonna have to view the two of them over and over before I "get it." The schematic/dynamic flow in the second one throws me off because I keep looking at the gauges to see the condition I'm dealing with, but the gauge never changes. Guess I'll have to actually start listening closely, something my wife says I need to do anyway... Go figure.

Stuck for the moment installing an hydraulic e-brake in the XR5.0, but I'll get around to this soon. May post photos of that install.
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Re: Scorpio A/C Troubleshooting

Post by brokencase »

John said it was knocking. Sounds like overcharge or too much oil?
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dimswits
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Re: Scorpio A/C Troubleshooting

Post by dimswits »

john keefe wrote: Sat Aug 20, 2022 1:35 pm Thanks Ed. Hope my AC problems aren't keeping you up at night looking for solutions. :) Only viewed both briefly, so I'm gonna have to view the two of them over and over before I "get it." The schematic/dynamic flow in the second one throws me off because I keep looking at the gauges to see the condition I'm dealing with, but the gauge never changes. Guess I'll have to actually start listening closely, something my wife says I need to do anyway... Go figure.
I'll say it again: You have zero circulation of refrigerant in this system. It is stuck in equilibrium. The primary cause of your problem is not an undercharge, not an overcharge, not too much or too little oil. It's not a failed expansion valve.

Your compressor is not working, and you need to figure out if it's due to the compressor itself, the clutch, the wiring, or the clutch control components. Everything else is just spinning your wheels.

I think people are getting confused because you are reading pressures in the system. All that means is that there is a charge present. Taken alone, it doesn't even indicate if the system is under or over charged.

In a closed, not operating system, the pressure will have a direct relationship with temperature. As I said before, your pressure readings are simply saying that there is refrigerant present in some quantity, and that at the time of measurement the temperature of the refrigerant in the system was around 88-90 degrees F.

Regarding the videos posted, those high and low side charts assume that the system is operating and that refrigerant is circulating.

Here's a static pressure/temperature chart: https://www.igasusa.com/pt-charts/R134A-PT-Chart.pdf
Dimitri in NYC
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Re: Scorpio A/C Troubleshooting

Post by john keefe »

Thanks dimswits, kinda' like churning water after the prop has fallen off. I'll be on it in a couple weeks when I get back, and will get back to you guys.
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Re: Scorpio A/C Troubleshooting

Post by Ed Lijewski »

This video with working gauge pressures exactly matches John's report and Dmitri's problem analysis:

https://youtu.be/6nNqocYgHc4

YMMV
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