2003 Pete 379 A/C

I've got a 03 379 with a 6nz C-15.
the a/c works great as long as the oil and water temps stay cool.

im pulling double belly dumps at 130,000lbs up 7 to 8% grades, the outside air temp is over 100.

when the oil gets to 205 and the water gets to 195 the a/c blows hot air, as soon as i get to the top of the hill it will cool back down to normal and the a/c will blow nice and cold again.

i run the engine fan all the time and when i wash the truck i pay close attention to spray out the condensor intercooler and radiatior.

the truck has a new condenser and a/c compresser.

any ideas??? Thanks...

 

thanks i'll try that.
also i had my buddy check the ac system and he said it was real low on freeon. he had to add a bunch to bring the levels up to good...