2003 Buick reagal air conditioner

Possibly a blend actuator fault. If an overtravel occurs, it is usually a symptom that the system will default to a full position, hot or cold. It will usually set a fault ode, but you need a scan tool that will access body systems, not just a powertrain code reader. Another concern is whether the compressor is engaging. If it is dual zone, and both sides are warm, or ambient, make sure the compressor is coming on when requested.

When the ac quits workin it blows warm air on both sides. Seems that once it is working it works fine but you shut the car off and the next time you start the car nothing but warm air. Seems like the compressor works one time and then the not the next time. I will look to see if the compressor is working next time it quits

Also if there is a fault code wouldn't it set off a service engine light?

Not if there are faults in the HVAC system, there is no visual indication to the driver. There can be powertrain faults that disable compressor operation, most of which illuminate the check engine light.

Friend of mine is a snap on tool guy. So i have access to most scanners. You recommend a specific one?

I am a dealer technician, have no product knowledge of other scan tools. If you can procure one that will access other body systems, that should be sufficient.

ok thanks for all your help.