I have a 99 Peterbilt 379 just replaced compressor. Never noticed but when the engine fan kicks on when high pressure reaches 325. The low side drops to 20 clutch turns off and turns on at 40 and so on until fan turns off then low side hovers around 30 on low side and high side goes up until fan kicks on again. Well what I'm trying to get at is this constant cycling on and off happening when going down the highway and is this normal? I'm trying to attach video but it's not letting me.
A/c cycling on and off
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by ran99, Apr 18, 2025.
Page 1 of 4
-
-
Trucking Jobs in 30 seconds
Every month 400 people find a job with the help of TruckersReport.
-
Have to use Lubetube or another video site and attach a link to the video in a post on here.
-
snowmantrucking101 and Diesel Dave Thank this.
-
Almost sounds like it could be overcharged.snowmantrucking101 and Star Rider Thank this. -
If it's cycling like that going down the road you either don't have enough air flow through the condenser (plugged with dirt) or you are way overcharged.
Oxbow, JB7, Diesel Dave and 1 other person Thank this. -
It's about 87 degrees in Florida and this is pressure with truck off and this is temp out of vents
Attached Files:
-
-
AModelCat Thanks this.
-
"Well what I'm trying to get at is this constant cycling on and off" Suppose to do that, depends on how fast it is doing it. Go back to post #5 from @ Star Rider. You can buy condenser cleaner at Home Depot etc. for $15 - $30 or order on internet. It is for home ac units but can be used on vehicles. Blow out with air first. Then use on the condenser, radiator, and charge air cooler.
Star Rider Thanks this. -
-
Trucking Jobs in 30 seconds
Every month 400 people find a job with the help of TruckersReport.
Page 1 of 4