gmc sierra ac cycling help

[gtc4d]

hello, I have a 04 gmc sierra, the ac compressor is cycling on and off about every 5 seconds. at first it was cycling and the high side was going to 400psi and cycling down. I removed some r134a and now i am cycling 50 to 75 low side and 75 to 100 high side. it is about 75deg outside. I have posted before this is the first chance i have had to look at the guages. when the low side goes low the high side goes high.
I am going to remove all refridgerant and replace the dryer but would like some advice if i need to check anything else while i have the system open. I will pull a vacuum and weigh in new cans, but i did this earlier in the year and it did not seem to help.

thanks,
Todd

[zz28zz]

IMHO, The 400 psi high-side press is likely due to one of 3 things.
1. Significantly over-charged system
2. Refrigerant blockage
3. Condenser airflow

Measuring refrigerant weight going back in will rule out #1.
Orfice tube inspection/replacement will help with item #2.
Inspect/clean the condenser and verify radiator cooling fan/s are OK for item #3.

While sys is empty, I'd definitely pull out and inspect orfice tube for black goo and shiny metallic particles..

[Tim]

Reclaim refrigerant, pull a vacuum, recharge to specs. Get baseline readings and start troubleshooting from there.