Ac works some times
HI. Here is a complete check list that will help you trouble shot thsi issue. You will find the problem in one or more of these areas stated below.
1. Check Drive Belts - The air conditioner utilizes a drive belt that supplies power to rotate the compressor, which is basically a refrigerant pump. If the belt fails the compressor has nothing to drive it, inspect and replace as needed to restore operation. If belt is intact proceed to the next step.
2. Check for Compressor Clutch Engagement - Turn the air conditioner to the "on" position and set controls to the coldest setting. Start the engine and allow to idle. Then open the hood and inspect the clutch at the front of the compressor, is it turning? "Engaged" if so, the system has enough refrigerant to activate. If the system is low on refrigerant it will not work properly. In this case an air conditioner recharge kit is needed to recharge the system. If the system is low on refrigerant it could cycle on and off, making a ticking noise. If the compressor clutch is not turning proceed to next step.
3. Inspect for Refrigerant Leaks - If the system has a large leak and no refrigerant remains it will not activate. First test system for a static pressure charge, with the engine off attach an ac gauge to the low side pressure port and check the state of charge. Depending on outside temperature there should be between 50 psi and 80 psi. (Cool and warm). A refrigerant leak detector is needed to inspect for leak, but if you do not have a leak detector there is an alternative method. The air conditioner system is designed to run with oil suspended in the refrigerant to lubricate the system. Check for oily residue outside the system by inspecting all hoses, compressor, condenser, evaporator or receiver drier and replace any component that has failed.
4. Inspect Fuses - Check under dash panel and under hood power distribution center. Replace failed fuses as needed, recheck system. If the new fuse fails when reinstalled a short circuit is present and requires diagnosing with a wiring schematic, follow circuits to locate short, repair as needed and recheck system.
5. Check Temperature Control Vents - The vents inside your car are controlled by a cable, electrical servo or vacuum servo. If the temperature blend door is not functioning properly it will cause warm air from the heater to exit the vents. To check this start the car and allow the engine idle, next turn the blower motor speed on low, switch the temperature control from warm to cold while your ear is close to the vents. You should hear the door move inside the heater box as it swings from open to close. If not, insect for a vacuum leak or a shorted motor in the servo, repair the leak or replace the servo motor...
Apr 20, 2009 |
2001 GMC Sierra C/K3500