A/C problems 08 Pacifica
 

Long time searcher, first time poster. I've learned a lot from reading threads here and I'm hoping someone can help me out this time.
Had an AC leak diagnosed by a shop as coming from the condenser. Husband replaced condenser, took it back to the shop so they could vacuum, replenish oil and recharge. They tell us now that the compressor needs to be replaced because the high pressure valve keeps releasing the refrigerant.
I'm not convinced.
We don't have gauges to check the pressures ourselves so I know I'm behind the ball there in terms of narrowing down the issue. When the car is on and AC is running, the compressor does engage, fans turn on high, rpms surge slightly (700-900) every 5 seconds or so and you can hear the pressure releasing.
I'm wondering if the high pressure is somehow related to the condenser replacement. We didn't have this issue before the condenser was replaced.
Please help me figure this out!

with the high side reading would show if there is a blockage in the system and cause the pop off valve to release the freon.

I'm planning on getting some gauges today so I can see exactly what the readings are myself. Any specific places that are common for a blockage after replacing the condenser?