Cummins N14 Overheating and ac problems

Have a 2001 Sterling with an N14 cummins. The fan doesn’t kick on at idle which causes overheating. It doesn’t kick on while driving until the engine gets to about 215 degrees and only comes on for a short burst, not enough to even cool it down. At the same time I’ve been trying to get the AC to work so I have replaced many parts that should go hand in hand with the fan. I’ve replaced both the high and low side ac pressure sensors. I have replaced the fan clutch air solenoid as well. I have taken a temp reading off the radiator hose and it seems to check out with the dash gauge so that leads me to believe the temp sensor is good. The ac holds charge and only blows cold while moving and still doesn’t feel like what it used to be. Every now and then while driving there will be colder bursts. I figured the pressure switch replacement would have fixed it but no prevail. Even when I unplug the fan solenoid and the fan constantly runs at idle, the ac still turns hot. The truck runs like a dog with the fan is constantly on so I want to get this fixed. Do I have two separate problems or am I missing something here?

 

I put the machine back on it and after charging and running it, low side pressure is at about 90psi so almost equalized with high side. Going to check to see if there’s an orfice tube. Only thing I can think of is it’s overfilled with oil.

 

Alright I’ve been able to work on this a little more recently. Here’s where the project is at today.

New Parts:
Ac high and low side pressure switch evaporator
ac pump
fan clutch solenoid
Orifice tube

Using 100 ester oil

Charged and recycled at multiple ranges from 2.4 oz to 3.2 oz. Same thing happens every time low side pressure slowly equalizes with the high side and stops around 190 psi. So the fan runs for a little bit then the fan cuts out, doesn’t start back up and truck overheats. I have gone through the system multiple times no leaks, electric looks good. Ac only blows cold when the truck is moving then gets hot at idle then truck overheats. Only thing I haven’t touched as of recent is the condenser and evaporator.