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Seville STS 2001, Eldorado 1997
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Discussion Starter #1
My STS 2001 had low freon pressure last year and I was able to successfully charge freon last year since the clutch was working when AC was turned on. This year it is different. The clutch is not turning on when AC is turned on (the car RPM remains same when AC is turned on or off). I guess the problem is low freon pressure. I checked clutch fuse, it is ok. I understand to turn the clutch on for charging freon, I need to short circuit the low pressure switch. Does anyone know the location of low pressure switch. Also I will appreciate the procedure of charging freon please.

Thanks
John
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,270 Posts
Re: Freon charging procedure - seville STS 2001

My STS 2001 had low freon pressure last year and I was able to successfully charge freon last year since the clutch was working when AC was turned on. This year it is different. The clutch is not turning on when AC is turned on (the car RPM remains same when AC is turned on or off). I guess the problem is low freon pressure. I checked clutch fuse, it is ok. I understand to turn the clutch on for charging freon, I need to short circuit the low pressure switch. Does anyone know the location of low pressure switch. Also I will appreciate the procedure of charging freon please.

Thanks
John
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I understand to turn the clutch on for charging freon,
I need to short circuit the low pressure switch.

no need to jump the low pressure switch -
just clear the LOW FREON code -

Does anyone know the location of low pressure switch.
yes - in the LOW PRESSURE line - near the orifice tube -

I will appreciate the procedure of charging freon please.
OK - the PROPER procedure:

since the AC system is a sealed system -
and freon does not get old - or weak -
it does not require periodic maintenance -

if the system is low on freon - there IS a leak -

so - the proper procedure is to locate and fix the leak -

then evacuate the system for a MINIMUM of 1 hour -
longer is even better -

add the correct - specific - 2.2 pounds of freon -

verify the high and low pressures are within the proper range -
depending on ambient temp - and relative humidity -

test the output air temp at the center vents -
37* is about as good as it gets -
39 to 42* is acceptable -
assuming 80 to 85 ambient -
50 to 75 humidity -

---------------

how DIYers try to do it -

screw the mickeymouse can/gauge onto the fitting -

jump the low side switch -

dump in an unknown amount of freon -
probably with some stop-leak in it -

put your hand in front of the vent -
if cold = DONE -
but add just a little more freon - just in case -

if not cold -
add more freon -

if cold = DONE
but add just a little more freon - just in case -

if not cold -
add more freon -

if cold = DONE -
but add just a little more freon - just in case -

if not cold -
add more freon..................................
 

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White Diamond '03 DHS (with DTS floor shift)
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86,783 Posts
You do not need to jump any switches to enable the clutch. Just clear the low refrigerant code.

Are you sure the clutch is not engaging? Look at it and get a visual. Don't go by RPM. Radial compressors are not as big of a load on the engine as the old piston type AND the PCM should compensate for the load and keep the RPM constant anyway.

Rather than checking the vent temperature with your hand, I'd compare the A/C pipes on the firewall. When you have enough refrigerant in the system, both pipes should be cold and the same temperature.
 
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