I have been having trouble with the auto ac system on this northstar for a while when system is turned the compressor keep cycleing on and off. the dryer line starts frosting over. need help to get the system to work correctly.

Do you have gauges? Need to check pressures.

Do you have a cabin air filter? If the fan isn't drawing off enough of the cold air through the evaporator, then the a/c will just cycle. Usually because the cabin filter is clogged.

. . . on?

. . . off?

. . . etc.?

yes i have a set of gauges.

when the ac and system is turned off.

no the hvac is turned off.

Let'* try this once again. What are the pressures at idle? Ambient temperature?

I don't have the car at this time. I put in the shop and the tech is pulling his hair out. I understand the hvac system but when the system is turned off the compressor shouldn't be still cycleing the clutch on the compressor.

If your in defrost mode it'll cycle when off.