Carrier Air Con Pumps

[moosemanusa]

Hi everyone,

Have an issue that's been bugging me recently, I'm researched it and nothing really gives me the answer, so looking for real world knowledge.

We have a Carrier AC System (RM-40 is the exact model) its an R22 system with the correct 45PSIG pressure.

However when cooling and sometimes (yes only sometimes) in  re-circ mode the pump will surge..

I'll feel the surge through the bus and also my ears pick up the change in engine notes, its like the pump is bogging down every rotation or few.

The system has oil and cools very very well.

Any ideas? Am I just being to paranoid (wouldn't be the first time) its just the 05G compressors are super expensive.

I've though about adding more oil to the system as I have no idea whats currently in it but still unsure if thats the issue..

Thanks..