naharra

Had the A/C charged on my 05 today at a local automotive shop and while the machine was hooked up the high side guage showed over 470 psi ............is that normal on these trucks?

kloppk

470 is too high... (unless it's ~130 degrees F outside)

At 70 degrees F ambient air temp it should be 150-250 psi
At 80 degrees F ambient air temp it should be 200-300 psi
At 90 degrees F ambient air temp it should be 250-350 psi
At 100 degrees F ambient air temp it should be 290-390 psi
At 110 degrees F ambient air temp it should be 350-430 psi
.................................................. .................................................. ....
If...
The low side pressure is
normal or slightly high, and
the high side pressure is too
high.
Then...
1. Condenser air flow
restricted.
1. Check the A/C condenser for damaged fins,
foreign objects obstructing air flow through the
condenser fins, and missing or improperly
installed air seals. Refer to Cooling for more
information on air seals. Clean, repair, or replace
components as required.

2. Inoperative cooling fan.
2. Refer to Cooling for more information. Test the
cooling fan and replace, if required.

3. Refrigerant system
overcharged.
3. See Refrigerant System Charge in this group.
Recover the refrigerant from the refrigerant
system. Charge the refrigerant system to the
proper level, if required.

4. Air in the refrigerant
system.
4. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.

5. Engine overheating. 5. Refer to Cooling for more information. Test the
cooling system and repair, if required.


.................................................. .................................................. ....

If...
The low side pressure is too
low, and the high side
pressure is too high.

Then...
1. Restricted refrigerant flow
through the refrigerant lines.
1. See Liquid, Suction, and Discharge Line in this
group. Inspect the refrigerant lines for kinks, tight
bends or improper routing. Correct the routing or
replace the refrigerant line, if required.

2. Restricted refrigerant flow
through the fixed orifice tube.
2. See A/C Orifice Tube in this group. Replace
the liquid line, if required.

3. Restricted refrigerant flow
through the condenser.
3. See A/C Condenser in this group. Replace the
restricted condenser, if required.

naharra

Good info.......will have a closer look..........thanks!

Zeus1987

what was the low side at ?

naharra

I changed the AC pressure sensor on the discharge line today and took it back to the automotive shop to hook it back up the the AC charge machine.
It spiked to 500psi and briefly spit out of the high pressure relief on the back of the compressor, then the pressure dropped to the 220-250 range on the high side and 23 - 33 psi on the low side.....we ran it for quite a while and it seemed to stay in that range.
I don't know what could have caused the 500 psi spike on the high side but it sure works well now.

Zeus1987

you could have too much oil in the system or your expansion valve could be ready to go.

500 psi .... dang that's high, we test our systems at 150 psi.