I hate to make another AC thread, but I couldn't find what I needed by searching. It's already really hot here in San Diego and I have to drive to Long Beach today, but with no AC. My compressor is not getting power, the system is charged, and the CCU is in good working order. What else could it be? Oh yeah, its on my 300sd.

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"spreading a trail of obnoxious where ever we go"
1981 300sd w/ 341,500 miles

http://www.wecrash.com/pics/ddda_banner.gif

Hmm, no takers. Does anyone know what pressure readings I should be getting out of the low pressure side when the compressor is not running?

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"spreading a trail of obnoxious where ever we go"
1981 300sd w/ 341,500 miles

http://www.wecrash.com/pics/ddda_banner.gif

Low pressure and high pressure should be the same without comp. running....the pressure will equalize...usually around 70-90 psi depending on ambient temp outside ....It is getting hot here in Central Ms. too....My brother moved to San Diego to escape the heat years ago.......
You could try putting +12 volts right on the compressor clutch terminal to see if compressor operates and read your high & low pressures with engine running to see if they are in the proper ranges...

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

There are also 2 pressure switches on the receiver drier. One for the aux fan, the other to engage the compressor assuming freon is enough. jumper the pressure switch. If you jumper the wrong one, the aux fan will come on!

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

The static pressure should be about 83 or 84 PSI on both low and high side. If it is less than that, the charge is low causing your problem. If the charge is indeed okay, then use a voltmeter at the clutch to see if there is voltage or jump 12V directly to the clutch with the engine off and listen for it to click. If it clicks then you don't have voltage to the clutch. Keep moving your voltmeter back through the circuit until you no longer get voltage and there is your problem.

The beginning basics of this troubleshooting process would be to check fuses and connections.

I don't know how to tell you to fix the a/c (though I can tell you how to replace the blower fan and module), but whatever you do, do it quick. Once the hot weather comes, you won't find any parts used if you want such things.

jeff

You could always move to the northeast..... gonna be cold up there again this weekend.

Check to make sure you have adequate pressure then try bypassing the low pressure safety switch on the receiver/dryer. My compressor seized last summer and two weeks later when I overhauled and fixed the system, it wouldn't engage because that switch wasn't working. I have it bypasses because I for darn sure wasn't going to open the system up again just for that. Now I just check the system whenever I think about it, maybe once a month or so to make sure its not leaking out. Its been good for about nine months now, knock on wood.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo