Need help with ac

[chevman]

Have small leak added 1 16oz can last May worked great till yesterday checked pressure and it was low again so I added another can yesterday working great again but here is the question I checked the pressure with ac on high it is within the range on the gauge then I turned on the rear air and the pressure goes up into the alert zone so I'm confused what pressure to go by I don't know much about ac so any advice would be awesome I am including pictures of the pressure gauge lower reading is ac on high the higher reading is with front and rear ac on high. Thanks

 

[djthumper]

Is this an EXT or a SWB?

Your profile isn't complete so we don't have anything for reference.

 

[chevman]

Have small leak added 1 16oz can last May worked great till yesterday checked pressure and it was low again so I added another can yesterday working great again but here is the question I checked the pressure with ac on high it is within the range on the gauge then I turned on the rear air and the pressure goes up into the alert zone so I'm confused what pressure to go by I don't know much about ac so any advice would be awesome I am including pictures ofView attachment 77308 View attachment 77309 View attachment 77309 the pressure gauge lower reading is ac on high the higher reading is with front and rear ac on high. Thanks

sorry it is the 2005 ext Lt I didn't thank the swb had rear air?

 

[Blckshdw]

The acceptable range for our trucks is 36-56 psi on the low pressure side. 200-285 on the high pressure side. What you've got going on there is nothing to worry about.

 

[chevman]

cool just was wanting to make sure. why a 10-12 psi higher reading when I engage the rear air? also should I check with the rear air on or off?

 

[Blckshdw]

I also have an 05 EXT, and have been dealing with AC issues lately, I noticed the pressure fluctuate when the compressor engaged. I had both the front and back systems on high while I was tinkering under the hood, didn't think to engage the systems separately.

But when it would click on, the pressure would go from about 38, into the low 50's. And when it switched again, it would go back down. Next time you check it and notice the difference, see if your compressor is (dis)engaging as well.