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6.0L Power Stroke Engine and Drivetrain Discussion of the 6.0L Power Stroke diesel engine and drivetrain in the 2003-Up Super Duties and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.0L Power Stroke engine.

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Old 06-13-2010, 03:34 PM   #1 (permalink)
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AC Pressure Readings

AC doesn/t seem to be as cool as it should. Need to check high/low pressure readings. What range should is normal
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Old 06-13-2010, 03:40 PM   #2 (permalink)
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Pressure Cutoff Switch a
Open status 2,999-3,275 kPa
(435-475 psi)
Closed status 1,586-1,999 kPa
(230-290 psi)
A/C Cycling Switch a
Open pressure 152-165 kPa (22-24 psi)
Close pressure 317 kPa (46 psi) maximum
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06/10 ARP studs, turbo back silverline, new head gaskets, new oil cooler, upgraded turbo drain, fuel pressure reg upgrade, coolant filter, high idle mod, harpoon mod, pre-pump spin on fuel filter,ELC coolant, 6.4 banjo bolts, CCV reroute.

Truck weight empty fueled up, 4440 Front, 3040 rear, 7480 gross. Hex VXCF4,
SCT w/customs tunes from Vivian at Quick Tricks and Matt @ gearhead
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Old 06-13-2010, 05:04 PM   #3 (permalink)
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Thanks for the quick come back
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Old 06-13-2010, 05:40 PM   #4 (permalink)
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these trucks have CCOT refrigerant system and pressures tell you little about low charge.
If you take an appropriate sized stick, pipe, a level, etc that can be inserted between seat and accel pedal and slide seat forward so that throttle is applied to get engine to 1300-1500 rpm. Set fan to one speed below high and use a thermometer (meat thermometer, etc that will read 30-100 degrees) inserted into center vent. Set control to MAX, if auto temp control set it to coldest temp and manually set fan speed as above.
A good gauge of charge level is to allow it to run in the conditions above and see if the large diameter line that runs down to compressor is as cold or nearly as cold as the large diameter line from evaporator case into the accumulator (aluminum canister in front of passenger side firewall case). If nothing is cold it is low or other problems exist. If the evap line is cold and the compressor is not then it is likely low and you can add R134a as a gas (can top up) for a minute and then shut off can valve. see if the compressor line is cold. If not repeat the gas adding phase and then monitor phase until the compressor line is cold. Better to go slow and monitor than to add liquid (can top down) and have it get overcharged or damage compressor from oil wash-out.
amb temp 80 L- ranges between 23-45 as compressor cycles
H 180-210

amb temp 90 L- lower 30's but should also range 23-45 after it cools down inside truck H 200-240

If the high side pressure is higher than the values listed you could have bad airflow from debris in condenser-rad-intercooler or fan clutch is not working properly or it has an obstruction in orifice.
Low side going rapidly to 23 psi and then the pressure on low side cycles rapidly between 23-45 with rapid compressor on-off can be low charge.
Low side being higher than what is listed above and high side being lower is usually faulty compressor having poor pumping-compressing capability.

Vent temp in the conditions as above after several minutes of running with windows up, doors closed should yield vent temps of 50F or a little below.
Debris on evaporator can cause everything to be OK pressure wise with vent temps not low enough. Heater door not fully closing can cause this too. Crimping heater hose shut and watching temps several minutes will tell you if it is heater door issue.
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2006 F450 CC Hauler bed 4x2 6.0 L Pstroke/Torqshift, Lariat, 4.30 r/a, SCT, 4in exhaust. 94 K
2006 F350 Lariat CC Dually 4X2, 6.0 TorqShift 4.10 LS, SCT, airbags, 4 in. exhaust. 147K
36 feet on the floor Elite/Outlaw LQ horse trailer.
36 foot double tandem axle flatbed trailer.
36 foot Sooner 6 horse large dressing/ mid tack.
2003 EB Expedition 141K
2004 Volvo V70R AWD-high miler in fleet, 205K

Last edited by jimmy; 06-13-2010 at 05:47 PM. Reason: additions
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Old 06-13-2010, 08:12 PM   #5 (permalink)
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Yes great post jimmy. I had my system charged recently after replacing condensor, drier and compressor. We put the wrong value in the charge machine, which meant I was about 6oz low on coolant.. the gauges still read fine, but it wouldn't cool very well until you got moving down the road.


An even better and safer way, take it to a shop, have it evacted and start over putting exactly what its supposed to have back in it.
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06 F-250 x/c 4X4 sb 17" alloy wheels. Tri-fold tonneau cover, weathertech vent visor,Ford floormats and splash guards. HarleyD headlights, Duplicolor bedliner coated bumpers, 08 rear bumper and taillights, herculiner rocker panels, XM radio, bosch wipers, Recon smoked cab lights, Edge Insight w/EGT probe, winter front.

06/10 ARP studs, turbo back silverline, new head gaskets, new oil cooler, upgraded turbo drain, fuel pressure reg upgrade, coolant filter, high idle mod, harpoon mod, pre-pump spin on fuel filter,ELC coolant, 6.4 banjo bolts, CCV reroute.

Truck weight empty fueled up, 4440 Front, 3040 rear, 7480 gross. Hex VXCF4,
SCT w/customs tunes from Vivian at Quick Tricks and Matt @ gearhead
http://www.fuelly.com/sig-us/59122.png
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Old 06-14-2010, 08:27 AM   #6 (permalink)
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Working on units that do not have a specified fill level, like limos, shuttle vans, customized vans, etc. you do not have the option of weight charging
If you set things up right and fill it incrementally you can get it right. Orifice tube units are easier to do this way than are expansion valve units with no sight glass.
When an OT system is full there is enough refrigerant at less than full cooling(fan speed set to less than full) that boiling is occurring in the suction line back to compressor. You want to add small amounts until you JUST reach this point. The only warning is that it needs to be warm, in the 80's or hotter for this to be used. If it is cool when you are partial charging then it will have boil going on in refrigerant line at way less than full charge.
The chill in the line to compressor is refrigerant that didn't have enough heat to boil it in evaporator. If you turn up fan to full that line will warm slightly since now there is enough heat to boil it in evaporator.
Automotive a/c units have to have some engine speed and working fans and clear air path through condenser for any diagnostics or partial charging to work. The compressor pulleys are sized to where the compressor pumping is below ideal at idle speeds so gauge readings will not be accurate and judging cooling won't work unless you take engine speed up a few hundred rpm.
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Don't tell my cattle I got leather seats!
2006 F450 CC Hauler bed 4x2 6.0 L Pstroke/Torqshift, Lariat, 4.30 r/a, SCT, 4in exhaust. 94 K
2006 F350 Lariat CC Dually 4X2, 6.0 TorqShift 4.10 LS, SCT, airbags, 4 in. exhaust. 147K
36 feet on the floor Elite/Outlaw LQ horse trailer.
36 foot double tandem axle flatbed trailer.
36 foot Sooner 6 horse large dressing/ mid tack.
2003 EB Expedition 141K
2004 Volvo V70R AWD-high miler in fleet, 205K
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