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93 Lincoln R12 Intermittent Cooling

Craig789 on Sat July 12, 2008 2:35 PM User is offline

Year: 1993
Make: Lincoln
Model: Continental
Engine Size: 3.8
Refrigerant Type: R12
Ambient Temp: 93
Pressure Low: 48
Pressure High: 330
Country of Origin: United States

While driving the 93 Lincoln, the air temp declines from 45 degrees to 38 degrees in about 15 minutes and then the clutch shuts off. Wait a while and the clutch will restart with the system working again, only to repeat the process. My theory is crud in the system was slowly plugging the orifice and causing a high pressure shut down. When the system shuts down, the backflow of the freon partially clears the orifice (or so I believed). Hooked up hoses to watch the pressure, but it works fine in the driveway (90 cooled to 55 degrees) Lo =48 Hi=330. Couldn't get it to go intermittent at idle RPM. Boosted RPM and the Hi side climbs dramatically to about 450 psi while the low side falls from 48 to 35 psi. Then smoke (not freon) from AC clutch and system won't come back on, even after cooling down. Clutch won't engage compressor now. Is there any chance this is just a clutch problem? If not, I will likely change the compressor/clutch, the condenser, the hoses to the firewall and the accumulator. Should I upgrade it to R134a? The R12 has been real cold.

Thanks,
Craig

Chick on Sat July 12, 2008 2:43 PM User is offlineView users profile

Check the clutch gap, should be about .02..If that is set correctly, then the cyling switch is supect..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Craig789 on Sun July 13, 2008 1:16 PM User is offline

Yes. Sounds like a good next step. Thanks. The clutch gap is wider than a business card thickness, so that would be too wide. Also the electric plug to the pressure switch needs cleaning. I pulled the clutch connector and established that it is seeing 13 volts, put it back on and (mysteriously) the system is running and cooling again (presumably still intermittent). I will post again in about a week when I have tightened up the clutch gap and cleaned the connectors. Anyone know the size of the clutch bolt on a 93 Lincoln? There is only an inch of clearance, so it looks like I need an ultra low profile socket and/or a very long wrench. Is there a "special tool"?

tony1963 on Sun July 13, 2008 5:56 PM User is offline

Nope. My diagnosis is a bad climate control panel and/or compressor relay. Once the circuit board heats up, the compressor stops working because of the micro air-gap between the solder connection and the pin on the board.

I've fixed a number of these. If you can feed 12v to the compressor and it kicks back in, check the climate control panel. You can buy rebuilt ones pretty cheap. If you are good with solder, you can take yours apart and check the connections.

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Grove Automotive Group, Inc.

An Alabama Corporation

Craig789 on Sun July 20, 2008 3:17 PM User is offline

Good idea Tony! I will be checking that. Do you think the high side pressure gradually rising to 330 psi in the driveway is cause for concern?

Dougflas on Sun July 20, 2008 4:56 PM User is offline

When you posted the high side, My first thought is airflow across condenser. That would account for high suction pressure. Spray yhe condenser with a water hose; if pressure drops dramatically, check fan clutch. Also if the high side drops, the low will drop also. Tell us the results. You may have two problems.

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