Ac Pressure

[cracker]

can anyone tell me what the low and high pressures should be when the ac compressor is on and do you need to re-calibrate the digital climate control when replaced? thanks in advance

[Carl Eagle]

can anyone tell me what the low and high pressures should be when the ac compressor is on and do you need to re-calibrate the digital climate control when replaced? thanks in advance

 

This was posted by Cracker on another forum, just a little more detail to help with the answer to his problem.

 

i changed the dryer, orfice tube, and pulled vacuum for 45 minutes, started charging emptied first can and clutch engaged but still cycling, started second can until cluch would stay engaged around 20 psi stopped charging to check temp. it was cooling but not as cold as it should be. started charging more up to 30-35 when it went warm and clutch would not stay engaged for any longer than 20 second intervals. thats it

 

What would cause the clutch to cycle on and off? I know a low charge would cause it but at 30 to 35 it shouldnt cycle should it?

Edited August 6, 2010 by Carls LQ9 SS (see edit history)

[wody]

what is the high pressure at?

[kcsilveradoss]

sounds like a bad low pressure cycling switch. tap it with a wrench (located on accumulator)

[wody]

sounds like a bad low pressure cycling switch. tap it with a wrench (located on accumulator)

 

could always jump it, and if problem still exists then you know there is another issue.

[cracker]

thanks for everyones help, i dropped the pressure to 20 and re-calibrated the mix doors or what ever they are called and all seems to be well except for when i stop and it starts to warm up again. i do have the fan shroud off maybe not enough air across coils was planning on putting e-fans on from FF DYNAMICS anyone ever try these?

[wody]

that is why i asked what the high pressure was, because i had a suspicion about air movement over the condenser. i'd say you have the right idea with the e fan swap.

 

keep it in the family:

 

http://www.silveradoss.com/forums/index.php?showtopic=57183

[blackbeast ss]

thanks for everyones help, i dropped the pressure to 20 and re-calibrated the mix doors or what ever they are called and all seems to be well except for when i stop and it starts to warm up again. i do have the fan shroud off maybe not enough air across coils was planning on putting e-fans on from FF DYNAMICS anyone ever try these?

thats normal when its very hot outside and you come to a complete stop, anytime your rpm is below 2k your pressures are gonna drop because the compressor pumps to its full capacity over 2k rpm.so anytime its very hot outside and you come to a complete stop your low pressure drops to about 20 to 35 psi moving your boiling temp and having a wide superheat causing less efficient cooling.thats why on CARs the best way of charging the ac is weigh in the charge.i seen alot of cars that are over charged because they charge the ac system till it starts blowing cold when its in park......wrong way to do it!!! the compressor will fail prematurely due to being overcharged........trust me my trucks ac is charged and running to factory spec and when i come to a stop and its very hot outside it will blow not as cold compared to when im driving....i recommend recovering the refrigerant and weigh in the charge!!!

Edited August 7, 2010 by blackbeast ss (see edit history)