06 3500 with newly rebuilt transmission, new clutch fan, new coolant temp sensor overheats to 220 at idle at intersections and stop and go traffic. Cools to 190 at highway speed under load. We haul cargo trailers on a 53' trailer. Fan seems to engage sporadically, under no specific conditions.

 

Does your airconditioning blow cold air? Sometimes the condensor will get plugged up with junk and severly diminish your airflow across the radiator which would explain your low speed overheating and it would also explain why your a/c wont blow cold air. Just my two cents, but I have to use a commercial refrigeration condensor cleaner and degreaser to clean my condensor out about once a year or I start to get the problem your describing.

 

Thanks for the reply....
There are some a/c issues, does not always blow cold and sometimes seems to freeze up? We had new fan clutch, new fan blade and new serpentine belt done...now low idle problem seems to be gone but truck is getting hot under load. Up to 220 yesterday. Comes back down but think that's too high or at least higher than it used to run. Load is about 12 - 14K pounds, what we usually haul.

Is there any other a/c fixes that may be involved? I did read somewhere that a/c pressure may effect it?

 

how does the coolant look> ? you did not mix coolants and turn them into mud did you ? tried a new t stat?

 

Don't think coolants mixed...different brands make mud??? Have put in new t stat and new coolant temp sensor as well.

 

I'd be looking at the air flow over your condenser and radiator. When I first had my truck the A/C didn't work very well at all. The hose between the radiator and overflow bottle had a bad connection, and plugged my radiator, reducing airflow through the cooling package.

 

Thanks for that input..checking connections, etc is something that we really haven't done yet. We have 400k+ on the truck, rebuilt engine and trans this year but some things may be original. Radiator is probably original...any thoughts on replacing and what kind of costs?

 

My 01 did this last summer going to VA. It would be fine idling, but under load get hot, and A/C wouldn't blow cold. Turned out everything was clogged between the radiator and intercooler. Cummins shop in VA steam cleaned it and it was perfect after that, no problems on the 12 hour ride home.

 

An 06 has the same puke bottle? I guess the one's i've seen have already been removed.
Those puke bottles sure will stop one up in a hurry though! Seen lots of trucks with literal inches of road grime and oil on the inner side!
If the coolant hasnt ever been changed you might do a combustion gas test on the cooling system just to verify there's no contamination.
PS, looks like the cooling system has been apart and although these trucks are not know for air bubbles causing cooling system issues, I would still consider taking it back to the shop and asking them if they vacuum filled your cooling system, and if not ask what efforts were made to eliminate air in the cooling system ...for instance a coolant funnel

 

Okay, so I'm confused. Is there a trap or something that can be removed and cleaned out? Or was there on 2001 but not 2006? We have added coolant several times (finally found out radiator petcock was leaky) and did so without funnel. Sounds like we MAY have air in system, but I'm still convinced overeating has something to do with air conditioner?