A/c cycling on and off

a/c unit runs great, but engine fan running constantly | TruckersReport.com Trucking Forum | #1 CDL Truck Driver Message Board
Diff truck but same concept with the fan. Post #6 explains.
Maybe @Goodysnap can get you the proper charge spec by oz and you can compare to what you put in.
At one point high side was down to 125psi which is low. In the middle of the video after the fan came on the low side jumps back and forth from 25 to 40 psi which is not normal.

 

Why was the compressor replaced?
Did you flush the system? Orifice tube replaced and installed in the correct flow direction? New dryer?

Evaporators and heater cores will also get plugged with dirt.

Sleeper 379 is usually 5 lbs. It’s never exact and it takes dialing in the amount for optimal performance.

share your ViN and I can double check the amount for you on Monday.

 

That was the clutch kicking in and out

 

Ok, still not normal to do it rapidly like the video shows. After the fan came on the pressure went up and right back down twice. Then there is a pause, maybe 5 seconds, and then did it 3 more times. Almost like a low charge would do but if low charge the rapid on and off would be consistent.

 

I would say it's perfectly normal with a low system.

High side rose slowly.
Fan engaged and high side dropped fast, low side drops till low pressure switch kicks out the clutch, pressure of course rises quickly and kicks the clutch back in, pressure drops, and consistently repeats the cycle.

But, I could be wrong.

Were it me, I would of put another can or two of freon in it two days ago and seen myself

 

OP never mentioned how many 12 oz cans he used.

 

"and consistently repeats the cycle." Middle of video: low side jumps from 25 to 40 and right back to 25 twice. Then stays steady for about 8 seconds. Then jumps from 25 to 40 and right back again 3 times. Then stays steady for about 24 seconds. Then starts jumping again before video ends with the fan running the whole time. Certainly not consistent.
Posts #7 and 12 recommend to recover the refrigerant and charge. #22 recommends to get spec for ounces to charge. OP can then see how close or far he is from spec. by comparing to how many ounces he put in. Posts 7 and 23 say 5 lbs which is 80oz or 6 2/3 cans, go with 7.
At this point OP needs to:
1 - Provide how many 12oz cans he charged the system with
2 - Provide his VIN # so the spec for his truck can be posted

 

Quit reading and put some freon in.

Good lord. The guy probably doesn't have recovery equipment, and has ALL the signs it's low on freon.

Hell, Ray Charles could watch the video and see it's most likely low.

Way too often folks overlook all the signs and trail off into rabbit holes that lead nowhere.

20$ and ten minutes and this guy can likely learn what is wrong, or he can sit here and read one post after another telling him different crap.

 

You said exactly what I wanted to say. The low side fluctuations are probably the compressor cycling. I can almost hear it clicking on and off. It’s barely cooling at 87 degrees outside. Most people quit adding when it seems to be working. They’re afraid of over charging the system. Works great till it gets real hot outside. Need that last can. It’s also needed to keep the compressor itself from running hot and prematurely failing. Slap a couple cans in it!! Lol.