Free Car Repair Advice by Professional Mechanics
Troubleshooting
/ Air Conditioner
Air Conditioner Not Working
Troubleshooting Procedure
Air conditioning facilitates the removal of heat from inside the vehicle. The
principle applied is that the heat is removed by the method of conduction and convection.
An evaporator which is cold absorbs the heat from the air that is passed through
it and then cold air is forced out through the vents inside the car by the
blower motor.
This is done by pressurizing refrigerant (134a) with a compressor and then releasing
refrigerant (134a) inside the air conditioner evaporator. There are many reasons
your air conditioner can blow warm air. A basic
a/c gauge and
test light is needed
to help diagnose most air conditioner problems. Always use caution when inspecting
an
air conditioner system, a/c systems contain high pressure gas that when released
can cause personal injury. Use all safety precautions.
WARNING! Before air conditioner repair work can be performed the system must be
evacuated of all
refrigerant or personal injury can occur.
Basic Checks and Information
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.
Air Conditioner Compressor
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).
Air Conditioner Pressure Gauge
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.
Leaking Air Conditioner Hose
NOTE: Before you replace any a/c component you must evacuate
the a/c system of any remaining refrigerant. Replace failed parts as required,
vacuum system with a vacuum pump and recharge using an
air conditioner recharge
kit. If system has sufficient refrigerant (134a) proceed to next step.
Air Conditioner System (appearance may very)
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.
NOTE: Regular Air Conditioner Maintenance Service your a/c system about every two
years. Activate your air conditioner system periodically to keep components lubricated.
An
air conditioner
service removes all moisture from the system by creating a vacuum that should be
held for at least 30
minutes. Internal system moisture is a leading cause of air conditioner system failure.
For exact specific repair procedures for any of the steps above visit our
online repair
manual page.
Troubleshooting
/
Air
Conditioner
Check Manufacturer Specific Air Conditioner
Questions and Answers
Related Subjects
Got a Car Repair Question
we will answer it for FREE!
GET A
REPAIR MANUAL
FOR YOUR CAR. Get instant access to your vehicles drive belt routing, wiring
diagrams, trouble code information and other available updates and factory bulletins.
| 
