A/C problem!!!
03-11-08, 06:12 PM
#1
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Location: Nevada
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A/C problem!!!
Hey guys. I live in Vegas and today my A/C just quit blowing! It is starting to heat up out here so I need to get this fixed now... Everything looks like its working but no air blows out. The compressor kicks on but no air. A friend said that its probably a relay. Anybody experience this before? Let me know.
Thanks guys,
Gary
Thanks guys,
Gary
03-11-08, 07:31 PM
#2
You can start with these:
If a system does not blow sufficient air, check for obstructions of the
fresh air intake or body exhauster vents outside the vehicle.
• Restricted (clogged) fresh air filter behind glove box needs replacement.
• The expansion valve may fail in the open mode as a result of debris
in the system (perhaps from a past malfunction). The expansion
valve can also seize in the closed position due to a loss of lubricant.
Apparent expansion valve failure may simply be a case of the
capillary tube (sensing bulb) not being in contact with the
evaporator outlet line.
• Paper, leaves and mud can clog the condenser fins. This reduces
system performance and can cause overheating and a blown fusible
plug or relief valve. The debris can often be blown out with
compressed air or a water hose. If necessary, special combs are
available to straighten bent condenser fins.
Clearing
Condenser
Obstructions
Bugs or dirt will increase
system pressures and
reduce cooling efficiency.
• A system which does not produce cool air or blows a visible mist
(even though the fan works) may have one of two malfunctions:*
1. An iced evaporator. This can be caused by using MAX cooling
with a low fan speed or a failure in the thermistor/amplifier unit
(to be discussed in A/C controls).
2. The evaporator drain hose may be clogged with leaves or mud
which will cause the evaporator housing to fill with ice and
water. This will restrict airflow. A wet carpet is one symptom of
a clogged evaporator drainline.
* Some mist or fog can normally occur on humid days when the
system is first switched ON.
• A simple way to check the operation of the electric fan system is to
unplug the coolant temperature switch or refrigerant pressure
switch while the ignition is ON. This will result in the fans running
at HIGH speed.
Troubleshooting,
Service and
Repair Tips
• Every system will slowly lose refrigerant through the front
compressor seal, especially if the system is unused for long periods
and the lip seal dries out. It is not unusual to lose half a pound each
year. At this rate, the system will lose its effectiveness in two to
three years. This slow leak will not be apparent during normal
maintenance and is too small to be detected with a leak checker.
• A system that loses more than half a pound per year has a real
leak. Leaking front seals may be easy to diagnose due to the oil
stains on the clutch and in front of the compressor. The seal is
easily replaced and on some models it can be done without
removing the compressor. When handling the front seal, always
coat your fingers in oil to prevent body oils and acids from etching
the delicate sealing surface.
Then try these:
A complete check of the mechanics and performance of the A/C system
will quickly reveal areas in need of attention. You can perform simple
and easy-to-do sight, sound and touch checks before starting the
vehicle or attempting to run the A/C system. These include:
1. Verify outlet temperature (35°/ 45° F) with a Performance Test (see
Performance Testing in this section).
2. Coolant Level. An overheated engine will not achieve full cooling
performance.
3. Compressor drive belt tension . At full load, the compressor
requires high drive torque to drive the belt. The Vehicle Repair
Manual specifies the correct tension.
A blinking A/C light indicates a possible compressor lockup situation.
After making any necessary adjustments, carefully observe what
happens right after starting the engine and switching ON the A/C.
4. Listen for the loud click that indicates the compressor clutch has
engaged (energized). Observe any unusual compressor noises.
Confirm that the electric fans immediately run at low speed.
5. Look into the sight glass (on receiver-drier, if available):
• It should appear clear, as liquid refrigerant with a few bubbles of
vapor flowing out of the receiver-drier (an almost empty system
will also appear clear).
• Excessive bubbles may indicate an undercharged system.
• A cloudy flow indicates the desiccant has escaped from its bag
container or there is moisture in the system.
• If there is no movement visible, just cloudy streaks, the system is
empty.
6. Carefully touch accessible refrigerant lines to confirm system
operation:
• Low-pressure lines should feel cold to the touch. In humid
weather, moisture may condense on these lines.
• High-pressure lines should be hot to the touch.
• A high-pressure line that feels cold indicates a pressure drop due
to an obstruction in the system such as a clogged fitting or a
crushed refrigerant line.
If a system does not blow sufficient air, check for obstructions of the
fresh air intake or body exhauster vents outside the vehicle.
• Restricted (clogged) fresh air filter behind glove box needs replacement.
• The expansion valve may fail in the open mode as a result of debris
in the system (perhaps from a past malfunction). The expansion
valve can also seize in the closed position due to a loss of lubricant.
Apparent expansion valve failure may simply be a case of the
capillary tube (sensing bulb) not being in contact with the
evaporator outlet line.
• Paper, leaves and mud can clog the condenser fins. This reduces
system performance and can cause overheating and a blown fusible
plug or relief valve. The debris can often be blown out with
compressed air or a water hose. If necessary, special combs are
available to straighten bent condenser fins.
Clearing
Condenser
Obstructions
Bugs or dirt will increase
system pressures and
reduce cooling efficiency.
• A system which does not produce cool air or blows a visible mist
(even though the fan works) may have one of two malfunctions:*
1. An iced evaporator. This can be caused by using MAX cooling
with a low fan speed or a failure in the thermistor/amplifier unit
(to be discussed in A/C controls).
2. The evaporator drain hose may be clogged with leaves or mud
which will cause the evaporator housing to fill with ice and
water. This will restrict airflow. A wet carpet is one symptom of
a clogged evaporator drainline.
* Some mist or fog can normally occur on humid days when the
system is first switched ON.
• A simple way to check the operation of the electric fan system is to
unplug the coolant temperature switch or refrigerant pressure
switch while the ignition is ON. This will result in the fans running
at HIGH speed.
Troubleshooting,
Service and
Repair Tips
• Every system will slowly lose refrigerant through the front
compressor seal, especially if the system is unused for long periods
and the lip seal dries out. It is not unusual to lose half a pound each
year. At this rate, the system will lose its effectiveness in two to
three years. This slow leak will not be apparent during normal
maintenance and is too small to be detected with a leak checker.
• A system that loses more than half a pound per year has a real
leak. Leaking front seals may be easy to diagnose due to the oil
stains on the clutch and in front of the compressor. The seal is
easily replaced and on some models it can be done without
removing the compressor. When handling the front seal, always
coat your fingers in oil to prevent body oils and acids from etching
the delicate sealing surface.
Then try these:
A complete check of the mechanics and performance of the A/C system
will quickly reveal areas in need of attention. You can perform simple
and easy-to-do sight, sound and touch checks before starting the
vehicle or attempting to run the A/C system. These include:
1. Verify outlet temperature (35°/ 45° F) with a Performance Test (see
Performance Testing in this section).
2. Coolant Level. An overheated engine will not achieve full cooling
performance.
3. Compressor drive belt tension . At full load, the compressor
requires high drive torque to drive the belt. The Vehicle Repair
Manual specifies the correct tension.
A blinking A/C light indicates a possible compressor lockup situation.
After making any necessary adjustments, carefully observe what
happens right after starting the engine and switching ON the A/C.
4. Listen for the loud click that indicates the compressor clutch has
engaged (energized). Observe any unusual compressor noises.
Confirm that the electric fans immediately run at low speed.
5. Look into the sight glass (on receiver-drier, if available):
• It should appear clear, as liquid refrigerant with a few bubbles of
vapor flowing out of the receiver-drier (an almost empty system
will also appear clear).
• Excessive bubbles may indicate an undercharged system.
• A cloudy flow indicates the desiccant has escaped from its bag
container or there is moisture in the system.
• If there is no movement visible, just cloudy streaks, the system is
empty.
6. Carefully touch accessible refrigerant lines to confirm system
operation:
• Low-pressure lines should feel cold to the touch. In humid
weather, moisture may condense on these lines.
• High-pressure lines should be hot to the touch.
• A high-pressure line that feels cold indicates a pressure drop due
to an obstruction in the system such as a clogged fitting or a
crushed refrigerant line.
03-12-08, 09:37 AM
#6
Driver
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Join Date: May 2003
Location: Nevada
Posts: 123
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Get this!
So today I start my car and now the A/C is working! Any thoughts on this? I guess everytime I get in my car I have a 50/50 shot on "weather" or not I will have A/C. Thanks for everyones help,
Gary
Gary
03-12-08, 11:00 AM
#7
Instructor
My guess is this has nothing to do with your A/C and everything to do with the ventilation motor system.
Sometimes, when the fan blower motor stops working, a good bump on the road will have it working, I have been known to smack my dash to get things going.
This maybe only a temp solution, the motor will eventually fail it could be tomorrow or it could be next year or longer.
Verify a bad motor, wait till it stops working again, apply 12volts directly to the motor to see if it works. If it does, then the problem is one of the other components in the system
Brushes inside the motor will wear out over time, much like brushes in the alternator.
The solution would be to rebuild the blower motor or just simply replacing it.
Easyer said than done, access to the motor is under the dash somewhere...
Sometimes, when the fan blower motor stops working, a good bump on the road will have it working, I have been known to smack my dash to get things going.
This maybe only a temp solution, the motor will eventually fail it could be tomorrow or it could be next year or longer.
Verify a bad motor, wait till it stops working again, apply 12volts directly to the motor to see if it works. If it does, then the problem is one of the other components in the system
Brushes inside the motor will wear out over time, much like brushes in the alternator.
The solution would be to rebuild the blower motor or just simply replacing it.
Easyer said than done, access to the motor is under the dash somewhere...
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