2003 Peterbilt 387 A/C issue...

could be an insulation problem does the floor of the cab next to the shifter gets hot?In that case inspect the exhaust pipe starting from the turbo all the way back to the end of the cab.You may have a hole leaking hot smoke there.

 

I have an 06 Pete and had issues with the AC working.... but not like it should be. It became increasingly noticible as the weather got really hot, it just couldn't keep the cab below 80f. It turned out to be all the hoses were disentegrating from the inside and sludging up the system. From what you describe it may be the same problem- especially if you've ruled out the basics. I had all new hoses made (it was cheaper than buying them pre fab) and installed. Every hose, it was not cheap, and Peterbilt did all the work, but they were also the only ones that figured it out. Hope this helps!

 

What is the temp coming out of the vents? MY 387 is 55* on a 90* day.

 

have you made sure the system is fully charged?

 

If ac working just fine and blows really nice cold air and than over some hour or two while you getting loaded it stops working good, than you drive to truckstop shut your truck get some to eat come back to your truck and boom it works fine again. So it means your ac is mechanically fine otherwise it would become inoperable permanently. I think and I know from my experience if I drive through humid weather during the summer my ac stops blowing. And I learned that it stops blowing because ice builds up on ac radiator inside your panel. Ice closes holes in radiator and you got warm air if it can go around radiator. In Volvo truck I hear fan spinning inside but air doesn't blow at all. No room to go around radiator. Same thing happening to sleeper ac but les likely cuz front radiator takes most of the humidity turns it to water and than to ice. But sleeper ac radiator only gets already dried air from the cab and recirculates it. Sleeper ac rad... Will freeze if you leave window open at least a littlebit. Ye I know how humid Florida is but don't worry solution is simple: just turn the ac button to off and keep the fans blowing at full speed for 10-15 minutes. Ac radiators become warm ice melts down and boom your ac is working perfect again. That's what's up when you come back to truck after lunch if you left truck shut of course. If it was running all the time and ac kept all that ice cold, it never melted and ac still wouldn't work. All right hope this helps. You can defrost you ac at any time while driving 10-15 min. Or you can shut your truck and wait inside the company while getting loaded. Trust me it has nothing to do with your trailer if it's loaded or not. Just coincidence. It's timing. I just bought my self a peterbilt 387. And I have issue with ac that I have no answer to, maybe some one could help me. My ac blows warm, compressor stops and goes, when I'm charging it pressure gauge goes up and down but never reaches green zone. Seems like my can of ac fluid doesn't want to get empty. Fluid is not going to system but connection is good cuz pressure goes smoothly up than smoothly down with same intervals.

 

John Family Farms... I know this is an old thread, but that happened to one of our 379's. It turned out to be a clogged orifice tube at the front cab Evaporator. 9First, recover all 9 refrigerant in the system. Second, Undo both high and low pressure lines of evaporator at firewall. Third , remove the orifice tube located just inside the high pressure line going into evaporator and replace with a new one of the same color ( but flush the evaporator if you can before reinstalling the new orifice tube. I found that even if I did vacuum the system, the AC would not work correctly because one side is plugged up with trash and not letting the refrigerant cycle correctly.