How hard does your a/c kick

[phill0072]

I am asking this because my a/c kicks hard when it cycles on. I mean when I am crusing any where between 60 and 70 mph light to no load cruise on, I can really feel the compressor come on, feels like the engine will miss real quick like 1 or 2 cylinders can even feel it when I am at idle dealer says this is normal some kick harder than others but it feels real hard on this one, never owned a truck or van that kicks this hard. it also fast cycles sometimes If I have not used it in 2 or 3 days it will fast cycle for like 5 minutes it cycles the compreessor on for like 30 seconds then of for 5 seconds "blowing warm air" then back on 30 seconds "blowing cold air" then off for 5 seconds and so on until it desides to just blow cold and cycle less when it cycles off for the 5 second and blows the warm air it makes a loud hissing sound then it goes away when it cycles back on dealer said it is just building pressure and some times it takes that long I have never owned a vehicle that does this they say the system is charged I don't know what to do please help

p.s. when it works its cold like it should be, and it will go thru the fast cycling with it in the max,regular and bi a/c modes it does not matter, the belt also chirps when it cycles on just a quick little chirp

[DieselMonk]

check if you have enough refigerant in your a/c. I think there is a bulletin for the a/c belt chirping... dunno maybe the belt is slipping too much...

[jbplock]

I..when I am crusing any where between 60 and 70 mph light to no load cruise on, I can really feel the compressor come on, feels like the engine will miss real quick like 1 or 2 cylinders can even feel it when I am at idle dealer says this is normal … it also fast cycles …the belt also chirps when it cycles on just a quick little chirp

Phil,

This in not normal (IMHO) , with my 03 the only time I can tell if the compressor cycles is at idle .. and that’s only if I’m listening carefully for a slight change in the engine sound .. like the difference between going from park to drive … cycling fast and loading down the engine as you’ve described indicates a problem .. Recommend you take it to a good AC tech ASAP … if the truck is still under warranty find another dealer.. good luck …

[torque]

I have never felt a thing in either my '02 LB7 or my '07 LBZ, when my AC cycles. Your's ain't normal.

[mark45678]

it may have "non-condensables" in it (air) creating high head pressure or it could be over charged , I would take it in for service and make sure you tell the tech what the issue is . all 3 of my duramax trucks you almost cant feel the ac on or off .

[Robyn]

I dont have a Dmax but Ac is AC and the compressor should cycle on and off with ease.
The pressures on a 134A system will be ON at about 40psi and off at about 18-25 psi depending.
The highside should be about 200PSI and this is at normal idle on a hot day.
The sucker should when first turned on just gradually drop the air vent temp from ambient down to about 40F at the vents depending on the ambient.
On a 90F day mine will blow 40F going down the road and will warm to 45 or so when idleing.

The compressor will cycle on and off quicker when the ambient temp is lower. (60-70) and even more when cooler. During the winter when the Pump is running in tandem with the defroster it wont run long at all due to the colder temps and if the outside is low enough wont even come on.

The cold warm cycle is not right. Get a set of gauges on it and see whats going on before you have serious issues.

Robyn