A/C problem 2011 Cascadia

High and low pressure switches at easy to check and replace.

Check with a jumper wire, no cost and no breaking sealed system. They are screwed on a schrader valve.

 

No, but should close circuit when pressure is ok, open when pressure is low or high.

They screw off and should not leak, has a valve just like a tire. If it is bad a good ac shop has a tool to change the core without draining Freon.

 

Almost certain that is the high pressure switch,had the same problem before and replaced the entire a/c system except for the evaporator.standig facing the truck,it should be on the passenger side all the way up under the firewall. Good luck

 

The problem could be to much pag oil.
Most new/rebuilt compressors come pre filled with pag oil from the factory.
if you add more oil on top of that the system could be overwhelmed with to much oil.
Freightliner should be able to tell you the amount of pag oil the system holds and the manufacturer of the compressor should be able to tell you if it was pre filled with oil.
Also there there should be a sticker on the truck telling you the exact amount of Freon the system holds.
You should never add more Freon then what is stated.

 

Let us know the final outcome please

 

In my 2010 and newer Coronado’s daycabs, they started using a Denso compressor, I’ve always been told to use Denso ND-8 oil. Not sure what’s special about it, just what I was told to use. According to my notes, there is usually 3 oz in the compressor, and 4oz added to clean system with compressor replacement. So 7 oz of oil in the total system. Our system charge is 3.13lbs of Freon. If you have a Denso compressor, Other than whether nd-8 oil is the same as PAG you seem to be close enough to work.
We’ve had a few trucks have issues kind of like yours, no order, just as I think of them....
#1usually the compressor fades out quickly, which will show in a high low side pressure 40-50psi at idle, but you’ve replaced that,
#2 if you don’t have strong air out of the vents, wash out your Evap, (I may look clean, but wash it anyway.) 1/4 air line adapted from a garden hose works well, remove fan to get to it.
#3 the blower motor has a speed sensor in it that can fail, if the computer doesn’t see speed, it assumes it’s froze up and kills the compressor,
# 4 low pressure switch
#5 fan switch not kicking fan in

Hope you have it fixed by now, if not hope this helps.

 

Just a shot in the dark, but does the outside air temperature display in your dash read correctly? The ECM will not allow the compressor to run if the outside air temp is too cold. If the sensor is bad or the harness is shorting that could cause your symptoms.