Tahoe 2011 A/C problem

Hi guys,I need help. I have a 2011 Tahoe with an A/C problem. Let me tell you what happens.When the car is cold and I turn on the A/C, everything works fine. After 20 to 25 minutes, the problem starts: the compressor clutch starts disengaging and then engaging again. Because it only stays engaged for a short time, the A/C doesn't cool very well.I checked the pressure, evaporator, ambient, and coolant temperature sensors, and all of them are reading normal.Can anyone help me with this?

What are your High and Low pressures doing when the compressor cycles?

First of all thank you for your reply.
When it's normal the high is 250 psi and low around 40 psi. But when the problem comes it's reach 200 psi the high and around 70 psi the low. And the compressor will disengaged and it repeated.
The compressor, condansor and the orifice are new.

I'm a little unclear on what the cycle is. What are the pressures when the compressor shuts off? How long does the compressor stay off for? What are the pressures when the compressor kicks back on?

After the Compressor and Condenser were replaced, how much oil was added to each component? 

I am wondering if, maybe, you have moisture in the system. How humid was it when the system was open? Was the system properly evacuated with a vacuum pump? How long did you keep the system under vacuum? 

Does this vehicle have Rear AC?  

Okey let me tell you what I get

1. When A/C is Off:
   • Pressure: Low 115 psi / High 110 psi it sames low Refragent (but my Q is why the problem happen)
2. Under Normal Operation (A/C On):
   • Pressure: Low 30 psi / High 200 psi
   • Status: Excellent (Compressor engaged continuously)
3. When the Problem Occurs:
   • Cut-off Pressure: Low 48 psi / High 240 psi → Compressor disengages 
   • Re-engagement Pressure: Low 70 psi / High 150 psi → Compressor re-engages
     
     Thank you for your help
      

Batdrest wrote:

Okey let me tell you what I get

1. When A/C is Off:
   • Pressure: Low 115 psi / High 110 psi it sames low Refragent (but my Q is why the problem happen)
2. Under Normal Operation (A/C On):
   • Pressure: Low 30 psi / High 200 psi
   • Status: Excellent (Compressor engaged continuously)
3. When the Problem Occurs:
   • Cut-off Pressure: Low 48 psi / High 240 psi → Compressor disengages 
   • Re-engagement Pressure: Low 70 psi / High 150 psi → Compressor re-engages
     
     Thank you for your help
     

Thanks for the additional info! I'm not really seeing any red flags in your pressure readings. The ECM won't disengage the compressor clutch until the high side pressure gets closer to 400 PSI. What was your ambient temperature during testing?

What scan tool do you have available? There should be 'A/C Compressor Disengaged History' PIDs in the Engine Control Module. It keeps track of the last eight reasons why the compressor clutch was disengaged. Does the A/C Pressure Sensor agree with your gauge set?

With your pressures, I'd suggest having another look at the evaporator temperature sensor reading when the problem occurs. Or, let the vehicle sit overnight and compare the evaporator temperature to ambient. Do they agree?

Thank you for following up on my issue. Let me give you the history of the problem based on the customer’s description.The vehicle was operating normally. One day, the customer was driving on the highway for a long period of time when he noticed that the evaporator was freezing up. He had to turn off the A/C until the evaporator thawed, and then he would turn the A/C back on.After that, he noticed that the cooling performance had become poor. He took the vehicle to a repair shop, where the problem was diagnosed as a faulty compressor that needed to be replaced.Accordingly, the compressor, condenser, and orifice tube were replaced. However, the problem was still present, so he brought the vehicle to our workshop to have the issue diagnosed and resolved.I do not know whether the correct amount of compressor oil was measured or not, nor whether the refrigerant charge is correct.According to the customer, the refrigerant was replaced three times, but the problem was never resolved.

Answering your Qs
Q1:What was your ambient temperature during testing?
Around 38C

Q2:There should be 'A/C Compressor Disengaged History' PIDs in the Engine Control Module.
RPM unstable
Battery Voltage
and its repeated

Does the A/C Pressure Sensor agree with your gauge set?
there was different around 50psi

I'd suggest having another look at the evaporator temperature sensor reading when the problem occurs. Or, let the vehicle sit overnight and compare the evaporator temperature to ambient. Do they agree?
I remmber the evaporator temp. sensor ready normal with the problem. I will compere it with the ambient. and see is there diff.

THNAK YOU