AC problem and engine service request: connected?

[Cozz]

Hi everyone, totally new here so need a bit of advice...
Two issues that I think are related.
1. The AC started pumping out warmish air so thought it needed regasing. Took it to a garage far from my local garage where it was found the AC was not working. All the lights on, all cables connected with power but no function. Still air came through.
They regased and it didn't work, told me to come back so they could investigate....
2. Since then the " engine requires a sevice" message has appeared and will not go. Took it to my local, who tried just about everything including emptying the oil and refilling but to no avail.

I'm at my wits end so any suggestions greatly appreciated...

[jlh3rd]

it helps to know what year car and mileage. Also, you need to try and be more specific as to symptoms .Troubleshooting a/c over the internet can lead to a twilight zone of time and money spent with no fix. What is the static pressure of the system, car off. Pressure gauges need to be connected to find out. Are the radiator fans working. Do you know if the blend/ mixing doors are sequencing properly. In other words, when you select ,vents, defrost, or heat, does the airflow get directed as it should? Are you getting a voltage signal to the compressor? ...Have you checked to see if the compressor belt is intact? These are just basic questions that need to be answered , then you can begin to do more troubleshooting as there are low,and sometimes, high pressure switches that need to be checked. Are you saying one day it worked properly and the next day it didn't? ....
Is your check engine light on? If so, have you scanned for codes? Do you have vida/dice? ...or does your local guy have it? It's needed for proper diagnosis.....