09 prostar a/c replaced everything still not working

Thank you very much justtrucking2, i will try the ambient temp sensor hopefully i can dig it out. thanks again

 

Sorry to tell you, but you are completely wrong about the ambient temp sensor. I have see you post this a few times and bite my lip every time and I can't let it go any longer. The ambient temp sensor is only for the LCD display in the cluster. It has absolutely nothing to do with AC operation. The wire harness you dug the sensor out of is famous for rubbing through within itself and shorting out on other wires. You probably just separated wires for the pressure sensor that were shorted on another wire and got lucky. Trust me, it has nothing to do with a/c operation. Further more, the ambient temp sensor is wired to the cluster, it doesn't even go to the body controller.

Air Conditioning Compressor Operation

The following interlocks must be meet for the A/C compressor to transition states from off to on:

• Ignition and Accessory voltage at body controller (Checkmarks at A1 and A16 at 1602 of B/C)
• Air conditioning request from HVAC control head to B/C (Checkmark at 1600_A2)
• Engine running signal (Engine_Running)
• Engine speed above 300 RPM (Engine_Speed)
• Low pressure input is grounded (Checkmark at 1600_B5)
• Freeze Probe Thermistor input is ≥ 38° F ( HVAC_Freeze_Protect_Raw above 2.4976 volts 1600_B13)
• A/C high side pressure is greater that 35 psi, but less then 218 psi (AC_High_Side_PSI) - Pressures may change due to programmable parameters. See table below.
• No HVAC fault codes active

 

Heavy is correct. Ambient temp. sensor was used in early Freightliner Cascadia's, not any other OEM, to help regulate A/C operation. Freightliner has stopped using ambient air temp. for a/c the last couple model years. I do not recall which year they stopped.

 

heavyd, on a earlier post you mentioned about body controller not sending signal to ecm for the engine fan to turn on, i think i have that problem getting code spn:2609 fmi:16. my fan is not turning on for a/c, which i think it gives me high pressure. what should i look for in parameters in the ecm. and what do you think should be changed. thanks

 

If you have a Cummins, under Features and Parameters

Fan Control - set to ENABLE
Air conditioning pressure switch - DISABLE
Fan control switch - DISABLE
Fan type - ON/OFF

SAE J1939 Multiplexing should be ENABLED
Air conditioning pressure switch - DISABLED
Fan control switch - ENABLED
Source address - 33 BODY CONTROLLER

 

Thank you very much I’ll check those parameters when I get home, thank you

 

Another thought is that sometimes the high pressure code is due to a failed sensor or wiring problem constantly, and so the body controller sees high pressure even when the system isn't running. You can see this at key on if you have access to Diamond logic builder software. If the engine is in-fact programmed wrong, if you have a fan override switch, it won't work either.

 

i will recheck the high pressure sensor,wiring when my truck gets back. one thing i did noticed in insite is no SAE J1939 Multiplexing ecm value,should it be like that? like i cant enable or disable, its just blank. and fan control switch disable. ill try to change those too. thank you very much for your help.

 

If you are able to expand the little + sign and open up that column, then it is enabled. Is this a screen shot from your truck? If so, the fan control switch is not set up correctly. Once you enable that, you can click the little + sign next to the fan control toolbox, which open the little toolbox and more options will become available. This is where you set the parameter to Body controller 33. This tells the ECM to accept fan control commands from the body controller through the data link.

 

cool so i do have multiplexing enable. yea thats a screen shot from my truck. when i go back to the truck on thursday, i'll enable fan control switch and make sure source address= 33 body controller. im thinking this has been my problem all along. thank you