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Old 08-19-2005, 09:24 PM   #1
nicpon
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Ac works but doesn't work

Hey all,
I have problem with ac in Jetta 99(body 99-04) 2.0 manual.
When i push the AC button on the ac light comes up but temperature of the air doesn't change until i start driving or rpm will go above 2500. When the car is in motion it blows cold air like it supposed to but as soon as the car stopps it doesn't blow cold anymore. The fan is working fine no matter if the car is in motion it blows same way.

Another thing i have noticed is that when the ac is on then every minute or so the rpm drop a little(maybe 100 or 200). Moreover everytime it happens it makes a quick not very loud sound, kind of like when you stick in a piece of metal inside the fan and take it out right after the fan blades hit it.

Like i said before this second issue happens only when the ac is on.
Can you somebody guide me in direction of troubleshooting this problem ?? If its somethign very complicated I won't attempt to fix by myself but I would like to know whats going on more less before I go to the mechanic.
Thanks
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Old 08-19-2005, 09:27 PM   #2
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who knows... send a message 2 ChrizV! (he knows errr, a lot.)
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Old 08-19-2005, 09:28 PM   #3
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Quote:
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who knows... send a message 2 ChrizV! (he knows errr, a lot.)

Jesus there are a lot of other people on here that know a lot too
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Old 08-19-2005, 10:15 PM   #4
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watever...
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Old 08-19-2005, 10:49 PM   #5
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Quote:
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watever...
Just take a quick look through this section (Repairs and Maintaince) and you'll see the majority of the people who help out are not ChrisV. I'm with Steven (99integra) on this one, theres plenty of helpful people.
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Old 08-20-2005, 01:19 AM   #6
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Check your gas charge.
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Old 08-20-2005, 01:24 AM   #7
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This seems to be a problem with alot of European cars. My fathers Alfa Romeo 164L does the same thing. Its just the way their air conditioning systems are engineered, but, I would check the freon charge just to be safe.
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Old 08-20-2005, 01:47 AM   #8
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well the rpm drop and the clicking you here is your a/c compressor clutch cycling onn and off, you probably have a small leak in the system and over time you have lost enough r134 to give poor performance, try not to use it iff possible till it's checked out, when you start losing enough pag oil your compressor is gunna get loud and eventually sieze,then you need major a/c overhaul because of the metal particles in the system, just save yourself some cash and get er checked, a good a/c shop will know exactly what they are doing and looking for.
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Old 08-20-2005, 02:05 AM   #9
nicpon
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I guess I will have to go and get that thing fixed. I also checked the freon and the preasure is at the good level according to the little tool i had. I wouldn't bother if the same thing would happpen to all jetta's but i have couple friends and theirs is blowing cold all the time. Now that i think of, they have different engines so maybe it works different with different engines.
Anyway I thought it was a common problem that most of jettas have but i guess its not.
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Old 08-20-2005, 02:13 AM   #10
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i would say that is not the normal operation of the system, what kind of little tester did u use and what did you hook it to?
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Old 08-20-2005, 03:10 AM   #11
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Are you ready for a book!!! I'll get you cool as a cucumber quick!!!

You said "The fan is working fine no matter if the car is in motion it blows the same way." Are you talking about the inside vent fan or the fan/s under the hood by the radiator. Does that car have a belt driven fan or an electric? If electric, does it have one or two fans? Not cooling at idle and cooling while driving is usually an indicator of an airflow problem over the condensor (by the radiator). First check to make sure that it is not dirty (clogged up with bugs, leaves, dirt etc.). If it is a belt driven fan then the belt could be slipping or the fan's clutch could be bad. If it has an electric fan the motor could be getting weak. On alot of cars with two electric fans the ac will send a signal for the second fan to come on when the ac is engaged. Make sure the underhood fan's are working. A quick test to tell you if you have an aiflow problem over the condensor is to start the car and ac. Then if it is not cooling at idle like you said then have someone take a hose and spray a mist of water on the condensor and see if the vent air goes cold. If it goes cold then you likely have a fan problem. If it doesn't, then the problem is elsewhere. Remember, just cause a fan is turning doesn't mean it is turning the right rpm.. Your statment "temperature of the air doesn't change until i start driving or rpm will go above 2500" leads me in two different directions. The "temperature of the air doesn't change until i start driving" part tends to make me think its is an airflow over the condensor problem.
On the other hand, the "temperature of the air doesn't change until rpm will go above 2500" part tells me it might be a compressor belt slipping or a compressor clutch air gap problem. The compressor clutch air gap is the space between the clutch plate and the hub on the compressor. If the space is too wide the compressor clutch might never engage or it might only slightly engage (and make a metal sound like you said), and slip. If the gap is too little the clutch can engage even with the ac off and make a metal sound. This gap does change with temperature. For example, if the gap is slightly too wide and the car is in the shade with the engine off the clutch might not engage. Then, when you start the engine and go down the road the heat from the sun, engine etc. causes the metal components to expand and presto, the clutch engages. This space is gapped similar to what you do on spark plugs. The process of gapping it is usually done by adding or removing shims (basically different size washers). If you find this to be your problem then you will likely need to remove or reduce the size of one or more shims. This is common on compressors that have some miles on them. The clutch air gap should roughly be the thickness of a credit card (although all compressors have their own specifications). A good way to test the clutch air gap is as follows. Start car and ac. If at idle the air is not cold go look at the clutch on the compressor. If it is turning the the problem is elsewhere (make sure it is the clutch turning, not just the hub). If it is not turning, then take an object (stick etc.) and carefully tap in on the clutch. If it engages then the air gap is likely too wide and needs to be adjusted (by removing shims). Note: be careful doing this test cause of belts, fans etc..

The comment about the rpm dropping and the metal sound could be one of the following. It could be either the compressor belt or the clutch repeatedly slipping and grabbing. The compressor clutch is basically two round plates of metal that slam together when the ac is engaged. If the belt looses it's grip and then suddenly gains its grip (rpms lower) it could temporarily make the ac clutch slip (metal sound). Or it could be a problem with the compressor, but I don't think so. If the compressor had a problem it would likely make the noise continuously.

So, the following is what you should check:
(1) Clean condensor and do water test.
(2) Make sure under hood fan/s are working.
(3) Check compressor belt for tightness. Don't make it too tight as this can
wear out the compressor bearing (maybe about 1/4" of deflection).
(4) Check compressor clutch gap.

The refrigerant in an AC system carries the compressor oil through the system. If there is a leak eventually the oil does not circulate through the compressor and trashes it. For this reason there is a low pressure cut out switch. This is so that if there is a leak the system will shut down before it harms the compressor. The cut out switch deactivates the ac system when the refrigerant pressure lowers to a certain psi.. The pressure of the refrigerant changes according to the temperature it is subjected to. The higher the temperature, the higher the pressure and vica versa. The point I'm getting at here is that you could have a very slow leak and the refrigerant level could be low. Just low enough to activate the cut out switch. In other words, when you first start the car and ac, the refrigerant pressure is below the cut out switch's limit and the ac does not come on. Then, as everything gets hot from the engine (and even the sun) the refrigerant pressure rises and the cut out switch deactivates and the ac come on. A quick half-ass way to check the refrigerant level is to look at the accumulator/receiver/drier which ever your car has. This will be a metal cylinder looking can. On it there should be a little siteglass about the size of a dime. With the engine on and ac running look at the siteglass and you will see the refrigerant flowing by. If you see alot of bubbles flowing by then the system is likely low on charge. If you see only a few then you should be alright. The better method to check the charge level is with a set of gauges. If the air is cold when your ac does work and you don't see many bubbles then your charge level is likely alright and the problem is more likely one of the ones mentioned above. If the vent air is warmer than it used to be and you see alot of bubbles then it could be the charge level.
Do you own or have access to a set of gauges?

Post back what you come up with and we'll get you fixed up!!
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Old 08-20-2005, 05:08 PM   #12
nicpon
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Thanks for your replay.
The fan I was referring to was inside vent and is electric. I donít have to car in the garage at this time but I will have later on. I told my wife not to take and she forgot. Anyway I will perform these tests as soon as she gets back and then I will post the results.
For testing the pressure, I used one of those kits to recharge the ac. The one I used had the gauge(with levels drawn on it to let me know if I need to charge the ac or not) and as soon as i hooked it up the gauge was showing high pressure and that I donít need to recharge it at all.

I have to say something more about the sound I was talking about before. This sound doesn't sound like when you start the ac, when you can hear it kick in. Actually when I start the ac there is no sound all. The sound i was talking about is more like there would a piece of metal somewhere and it gets in a way with something else(it sounds to me like a fan but it can be something completely else).
I will take a deeper look and will let you guys knows.
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Old 08-20-2005, 09:41 PM   #13
nicpon
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This is what Iíve done:
I couldn't find the condensor even though I know it looks like small radiator so I had someone sprayed water on the grill and the air hasn't changed (still warm).


I have two electric fans on the radiator, when i turn on the engine and ac is off the fans are off too. When I turn the ac, the fans stay off(no movement at all). If I add some gas the fans kick in (but not every time) and they run pretty fast. As I was doing that I was looking at the ac compressor and on the side of the compressor on the wheel there is a triangle (attached pictures) that triangle makes the sound every time it tries to start and thatís the sound I was talking about before. This triangle will start and move for a little bit or it will make two spins and stop. The will itself moves pretty smooth without any problems and i have noticed any slipping I have made a short movie, here is the link http://www.nicpon.net/jetta/MVI_2580.AVI its about 20 MB sorry didnít have any tools to convert it to something else.
Attached Images
File Type: gif IMG_2582.gif (87.6 KB, 9 views)
File Type: gif IMG_2586.gif (97.5 KB, 7 views)
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Old 08-21-2005, 05:04 AM   #14
Macc
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After seeing the video I now tend to think that the problem might be one of the following: a weak clutch coil, a bad cut out switch, or the system is either under or over charged. To to figure out which and get closer to the problem answer the following questions and perform two tests:

(1) (Before you added refrigerant) When the ac was working (you said it did driving down the road), what would you say the air was; warm, cool, cold, or really cold. Also, did the temperature feel the same as it used to before this problem?

(2) When you hooked the gauge to it was the engine running (and ac on) when you saw the high pressure? Also, was this before or after you added the refrigerant. Note; don't add any more refrigerant until we get things figured out. Doing so could cause more damage.

(3) Before you added the refrigerant did the clutch (triangle thing) ever spin at all when not driving (at idle). Is the video of the compressor before you added refrigerant or after?

(4) How much refrigerant did you add? Have you ever added refrigerant to it before? If so how much and when? Also, has anyone else added any to it in the past? If so how long ago?

(5) It's kind of hard to tell from the video but it appears that the compressor (clutch) is cycling on and off pretty rapidly. When it is turning how long does it last? When it is not turning how long does it last?

(6) After adding refrigerant did you take it for a drive and run the ac. If so how did it work? Any problems?

(7) Do you have access to a manifold gauge set or atleast a single gauge that has numerical values (this would really help in diagnosing the problem quicker).

Here are two tests that you can do:

To test the clutch coil, unhook the electrical connector that goes to the compressor. It should have two wires. Determine which is the positive and which is the negative. Then prepare a length of wire to go directly from the positive battery terminal to the positive on the compressor connector. Route the wire so that it doesn't get caught in anything. Attach the wire to the compressor's positive connector. Then, start the engine, turn the ac on, and set the vent fan to high. Then, as you watch the clutch, have someone touch the jumper wire to the positive battery terminal. Only jump it for a couple of minutes for reasons I won't go into now. Watch carefully to determine if it spins contiuously during this time and anything else it does.

To test the cut out switch you need to locate it. I'm not sure where it is on your car because all vehicles are different. Often it is on or near the accumulator/receiver/drier (which ever your car has). Anyway, here is how to find it. Start at the firewall with the larger line (the low pressure line) and follow the routing of the system until you come across it. It will look like an electrical connector that is screwed into the system. It will only have two wires. If you come across one with anymore than two wires don't mess with it. Once you find it unhook the connector. What you are going to do is jump the connector with a paper clip or something (the two terminals). Don't jump the switch side of the connection, jump the other half. When you are ready, start the engine, turn the ac on with vent fan on high, and have someone jump the connector as you watch the clutch. Once again, take note as to what the clutch does and only jump it for a couple of minutes.
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Old 08-21-2005, 06:00 AM   #15
nicpon
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I have never added the refrigerant. I was going to but never did once the gauge was showing that the pressure is high. While the car is in motion the ac works fine, blows very cold and it has been like this forever. This car has only 48k miles and i got it during the winter time and I forgot to check if the ac is working. It was about O degrees outside so i didnít bother plus at that time if put fan to cold it blow cold from outside.

1)So like I said I donít know if ac was charged before i got the car but since the day I turn the ac on it's been very cold while the car is motion.
2) When I hooked up the gauge the engine was in motion and the ac was on. I didnít add any refrigerant because the pressure was high (I don't recall how much was it but i could get that gauge again and check it)
3) The video of the compressor I took today.
4) I answered this question before
5) Yes the clutch is cycling on and off without a pattern. For example, it will try to start few times with one spin and then it will spin for 10 seconds and this only happens when I add gas. Without gas it wonít even try to start.
6) Iíve never added any
7) I will try to check the pressure again and remember the numbers.

I will do these tests tomorrow morning because itís a little late now.
Does the clutch supposed to be spinning all the time ??
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