Ac not cold am told there is a compressor cut off when the radiator fluid is low. how do I reset?

Probably the refridgerant has escaped through a leak. Take it to a garage that charges aircons for investigation.
The usual culprits are the service valves and the condenser rots out.

first off learn how AC works, for sure this, set of hard logic, in the system for self preservation.
and if you had used the OBD2 SCAN TOOl first after fuses checked
you'd already know this.

1. high/low, R134 pressure switch tripped saving the full destruction of the compressor. a volt meter finds this truth also.
2. the controller AC also cuts AC if engine overheats or the sensor lies.
3. the control AC cuts AC at wide open throttle.WOT
4. AC cuts AC if engine IN gross DTC errors, or in limp-home mode to protect it and the driver, so more power is on tap from engine.
5. evap core sensor , sees freeze up and icing, Ice can do damage so it cut the compressor dead(means clutch off line)
6. the controller detects ambient temps WAY to low and cuts AC.
7. The dash controller AC is failing, but manual AC? not really if it's lamp glows for AC , the main controller is BCM on most cars.
8. the dash HVAC blower must not be dead or AC stay off line

Cooling radiator may need cleaning and the system may need topping up or new fluid entirely. Any work needs to be done by proper air technitians as it contains dangerous stuff.

go with the ac guy
there are systems that prevent the ac compressor working
high pressure switch which cuts the ac clutch if the head pressure goes too high
low pressure switch which cuts power to the ac compressor if there
is no gas in the system
climate control systems which cut power when the ac is not required
fuses to the ac system
get a better explanation or seek advice from other ac mechanics

Low Freon does those symptoms too. Too low to start the A/C system.

you can run the compressor for a few minutes to see if you get cold air with the low pressure switch crossed out. if you don't have cold air after about 5 minutes then you still have a leak somewhere.

If the car was retro fitted with R134a this was a common problem. There was a low side pressure sensor that needs to be changed. R134a runs different pressures than the r12.. When you go down the road the condenser cools off the system and the pressure drops below the minimum pressure. You need to make sure that the system is fully charged, not just cold to the feel. Both pipes coming out of the firewall need to be the same temp. this makes sure that the evaporator is flooded.
I hope this helped. Re-post if you need more info. Have a nice day and good luck.

If it actually is freezing up,the low pressure switch is the likely cause.It is screwed into the large ac line near the firewall,witch is the cold line.If it is not there it is in the dryer,near the firewall,or under the air filter box.Follow the ac line(large ac line/hoses)from the ac compressor untill you come to the switch,that is the easy way to locate it.This low pressure switch causes the ac compressor to cycle on and odd according to the pressure sensed from the ac low side line.When it gets really cold the pressure is lowered,and there for it will cut off,and when the pressure rises,it cuts the ac compressor back on.It would be a really good idea to check the freon in the vehicle first.If the ac system is low on freon,it will freeze up on some vehicles.

I dont belived having bigger radiator make your ac unit run better although radiator has nothing to do with ac beside colling your engine. If that was an issue to all cases, i think GM would have recall all of their envoy due to cooling issue, that's not so. If the car has been running fine since it was band new and now it started to have this cooling problems, I dont understand how can one come up with and idea that the radiator is too small, that dont make sense to me. Your eveporator sit in front of your radiator it may not have good flow of air movement to cool down the hot gases in the evaporator, maybe fan clutch is not working properly keeping the fan run at constant speed. The unit mabe also low on feon and not having enough feon in the systems causing your systems not to run properly. Low pressure or low feon will cause the unit also to run poorly and will caused the pressure switch to cut compressor on and off more frequent. Have the pressure tested and filled if need first. being 2003, if with high miles; its it good time to also have your thermostat replace if you never have it done. Hope that help some

HI, giving the compressor 12v directly is not the way to go as you are bypassing the entire fail safe cercuit. it seem to me that your ac gas is low(can be checked via ac pressure gauges) wich means you have a system leak sumwhere. as soon as your hi/low pressure switch(depending on system) detect inferior pressure to the spesified pressure ,the ac compressor voltage is cut in order to protect the pump from seizure.

Or perhaps your evaporator(small radiator like unit behind dash) can get freezed up caused by either too mutch system gas(check pressure) or poor opperation of the expantion valve. the evaporator then has a sensor(themometer) wich measures evap. temp and if the value drops below spec (usially round about7degrees) the ac compressor will be cut once again(fail safe)

Maybe your ac compressor overheats due to inferior system oil/oil capasity, also note that only some systems incorperate the function of measuring ac pump temp. then again temp to high= fail safe=no12v to ac pump.

Good luck.
gk