99 Peterbilt A/c cycling on and off

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.

 

Have to use Lubetube or another video site and attach a link to the video in a post on here.

 

Are you sure the system has enough freon? The only sure way to know is to drain it and recharge it.

 

Normally with low refrigerant the low side pressure drops off quick and the high side doesn't build up.

Almost sounds like it could be overcharged.

 

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.

 

It's about 87 degrees in Florida and this is pressure with truck off and this is temp out of vents

 

I have a 2000 379, I can't remember but I want to say it takes 5lbs. I would start by having it drained and recharged. A/C systems in 379 work well and blow cold when working properly

 

Did you replace the compressor or did a shop? Compressors are not plug and play. Did the compressor blow chunks? If so should flush and install a filter. There is also an adjustment for the refrigerant oil. Was the system evacuated before being charged after the compressor replacement?

"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.

 

I did myself I did flush vacuum replaced condenser compressor orfice tube and filter can

 

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