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Help w/ AC Diagnosis

I recently purchased a 1994 Crown Vic, and the AC is not working. If I check the system with the manifold gauges I'm getting the following readings:

With the system off, the low side is about 40 psi and the high side is

  1. With the pressure sensor jumped out so that the clutch will engage, the low side goes all the way down to -10 and the high side climbs to 85 psi. As soon as I pull the jumper the low side goes back to 40 and the high side to 0.

Can someone point me in the right direction as to where I might start to look?

Thanks!

Reply to
Jacob Burnetski
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Make sure your high side gauge is accurate. Add R-134a. Sounds like you will need 2-3 cans of it. With system off, both sides should equalize about 85-100 psi. Running the low should be around

30-38psi. High should be 190-265psi.
Reply to
Uncle Dodo

You're low on refridgerant. The low side should never be in vacuum. Low side should be about 30 psi and high side around 250 when the compressor is on. The needle should be steady, not wiggling. If it's wiggling, your compressor is in need of replacement. I would suggest that you fix the leak in your A/C system or the R134a that you put in will just leak out again.

-Bruce

Reply to
Bruce Chang

Reply to
Jacob Burnetski

You should have a decal under the hood with the proper charge weight. The charge weight is for an empty evacuated system and, does not matter if you are supplementing a system - you must rely on a good set of guages based on the temperature/pressure charts found in many service manuals. You may be able to find what you need at the local public library. Although I have never needed to go looking for it, I would assume this info is also available somewhere here on the net. Try a google search.

Reply to
lugnut

With the system off, both sides should quickly read exactly the same pressure and that pressure is only dependent on the ambient temperature of the system and the type of refrigerant inside the system. For R12, the pressure should be just about the F temperature, and for R134A, it should read about 10 psi higher. If this is not true, your gauges or hookup is faulty so fix that first. Since your static pressures don't make sense, you shouldn't trust the operating pressures to diagnose a problem. At

85F, R134A should read around 95 psi. > I recently purchased a 1994 Crown Vic, and the AC is not working. If
Reply to
Stan Kasperski

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