1993 300D: what should the low side pressure and high side pressure be with compressor running? mine is at 40 low side (blue hose) and 225 psi (red hose) on high side? is this normal?

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2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
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Semper Fidelis
USMC 1973-1976

What was the ambient temperature? that will be the most important defining factor.
If you do a google search for Refrigerant Temperature Pressure charts I'm sure you'll find something.
Also:
Was the engine at idle or 1500 rpm as recommended?
Did you have the auxilliary fan running?

Danny

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1984 300SD Turbo Diesel 150,000 miles

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yes the aux fan was running, engine at idle thanks

__________________
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

There's a chart here:

http://www.ackits.com/index.cfm?fuseaction=Chart

The pressure should come close to matching the outside air temperature.

What temperature were you getting out of the vents?

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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It needs to run at that high idle at least 10 minutes to get things stabilized and moved around in the system... for accurate readings...

This may sound silly but I'm still reading on A/C recharging, I'd assume Low side will increase accordingly to High side? So if my High side is correct my Low side should also (all else being equal)?

Also, what's the best way to monitor ambient temps outside?

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

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That's true to a point. without getting too technical these systems are designed with a specific charge to achieve the desired pressures. So yes, If your charge is good then your high and low sides will be right.
Of course other things can come into play that can cause innefficiency.

This is right from the chart link I gave you:
R-134a PressureTemperature Relationship Pressures shown in the charts are provided as a general guide and may not represent your exact readings. Ambient temperature is measured 2 inches in front of the condenser.
Go to the nearest hardware store and buy a $2.00 dial thermometer.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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Uh, you might try using a thermometer.

You should be measuring ambient within a few inches of the condensor.

Parameters necessary for system evaluation. First run at 1500 RPM with a/c max and fan high.

Low side
High side
Ambient temp
Vent temp

With this information and access to the p/t chart FOR YOUR MODEL CAR, the system performance can usually be analyzed.

Have a great day,