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SUVs Chevrolet Suburban & Tahoe Chevrolet Suburban and Tahoe AC and Climate Control Questions
136 messages, Last post on Nov 05, 2009 at 9:24 AM
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Replying to: krmarshall05 (Jun 27, 2008 6:53 pm) |
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Replying to: natale (Jun 29, 2008 4:38 am) |
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Replying to: natale (Jun 29, 2008 4:38 am) I understand that you have found out that the noise comes from the AC compressor? So, if you turn the whole heating / cooling system OFF you do not hear it? In some cars, like in my '04 Tahoe, AC compressor runs almost always regardless if you are heating or cooling. Even in heating mode some systems use AC compressor to dry the air so your windows do not fog over. That is why compressor typically runs if you select the wind shield operation. If the noise really comes from the compressor, like I believe it does based on what you say, there is one very simple and inexpensive thing to do to see if it helps. Go to any auto part store and buy a can of oil charge for the AC system. Your car is 6 years old and possibly has never had this done. Just like in any oil lubricated system the oil loses its lubricating properties over time and this can lead to wear and ultimately burning of your AC compressor. To charge your AC system requires a charging hose, which should not cost more than $10. Anyway, the can of oil charge and the hose will cost less than $20. If you don't have a handy man at home to do the job I would think someone at parts store might do the job for you but you will need to buy the can and the hose. The job is very easy and you probably can do it yourself too. You first make sure the needle valve on the charging hose is turned all the way open. This ensures the needle on the valve does not pierce the can when you screw the can in the valve. Then you unscrew the plastic cap from the low pressure service port in the cars AC system. This is the port right close the AC dryer canister (aluminum bottle at passenger side on fire wall). This line is also the one that is cool to touch (when AC system is running). When feeling the line do it next to the service port because the same line is HOT if you touch it on high pressure side of the expansion valve. In my car the expansion valve is just about 10 inches before the service port in this same line so the same line has hot and cold parts to it. You will connect the charging hose to the low pressure service port (the fitting on the hose will not fit in the other ports if you have purchased correct charging hose) while the engine is running on idle with AC on max cooling. Then holding the can upside down you will turn the needle valve on the charging hose to full closed. This will pierce the can. After this you open the valve holding it upside down and the ac system will suck the contents in the system. You will need to shake the can before you do all this and they instruct to shake it while it is flowing in too. It only takes about 30 seconds for the oil charge to flow in the system. If oil charge gets rid of the noise you should be fine as you say the air coming out of the vents is ice cold. If oil charge does not help at all you might have a bearing problem with the compressor. Bearing problem can be such that when you accelerate the extra force from acceleration can cause the bearing to make noise but when you drive constant speed or do just moderate acceleration during driving noise is not generated as acceleration force is not big enough to cause problem. If it is bearing issue you could try lubricating the bearing but it is very difficult to do and probably requires removal of the clutch and pulley that turns the compressor. $500 is not bad for AC compressor change as just the part for my car costs almost that. I guess the mechanic was talking about the cost for the compressor, not it installed. For the job you need to re-charge the system and to do that correctly the system must be vacuumed first after compressor change. And if you are to have compressor changed you probably want to replace expansion valve and the AC dryer canister too. At least that is what I would do if I had to replace my compressor. With all this work and parts you might be looking a bill around $800 instead of $500 so please do yourself a favor. Try the oil charge first as if the compressor is just running little dry it might save you that $800! Arrie
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| The rear air doesn't work on my '02 tahoe. I checked the fuses in the box but couldn't find any that where blown, any ideas? | |
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Replying to: dwalton1 (Jun 09, 2008 12:11 pm) |
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Replying to: arrie (Jul 12, 2008 8:55 am) Good Morning! Thanks for getting back to me. Yes when i shut everything down, Heat/Ac and drive the truck it runs normally, no sound no nothing. I am going to try and charge the system as you suggested. I will let you know how it turns out. Thanks for the detailed instructions it was very helpful. I hope this works. I would really have to go through changing the compressor and having to spend $800.00. Best Regards, Natale
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Replying to: natale (Jul 14, 2008 3:15 am) please post back wether it helps or not. This way it helps others in this forum too. Thanks, Arrie |
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Replying to: krmarshall05 (Jun 27, 2008 6:53 pm) I looked up the service bulletins on this truck and 01139B is the exact issue. Doing some more research, I found that it's a down problem where slugs of liquid refrigerant are being pushed into the compressor. They clog a tube which then blows the tensioner. Ugh. I'm pissed because the AC kicks just fine. It's cold and the fan works. It's just noisy as all getout and sounds like the belt is going to go flying. This wasn't happening prior to them replacing the belt or the tensioner. I'm wondering if they could have reinstalled something wrong and caused the problem. The shop quoted me $1300 to replace the compressor, tube, tensioner, etc. I just don't want to put that money into this truck right now. I'm having a hard time believing that this is the issue, if it was, it would have done this before the new belt. Right?
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Replying to: waltherchic (Jul 21, 2008 6:52 am) If the issue is that ...slugs of liquid refrigerant are being pushed into the compressor... then the fix for that is very simple...let some refrigerant out from the system. This is very easy to do. Just have a refrigerant charge hose connected to the low pressure side service port and let some refrigerant out. Have hose spraying in a container or something covering it with paper towels or something else so the refrigerant does not get on painted surfaces. It could hurt the paint. If you let out big amount of refrigerant you might want to add an oil charge after that to make sure you don't drain the system from lubricating oil that the compressor needs. If your compressor runs well and works, i.e. cools the air then if the compressor itself is quiet there is no need to replace it. And if it makes noise oil charge can fix that too. The tensioner breaking right after new one is installed does not make sense. The tensioner simply is a pulley mounted in the end of an arm that is spring loaded against the belt. The way tensioner normally fails is that the bearing of the tensioner pulley wears out. Very seldom the spring breaks but is possible. Almost sounds like the shop that fixed your tensioner installed the old broken tensioner back in and then tell you you need to replace $1300 worth of parts to fix it. I say this because I see so much scam amongst the car repair shops and it is getting much worse in a hurry. And it seems dealer service shops are amongst the worst ones with this. I don't know if you are a hands-on person but a belt tensioner is not very difficult to fix/replace. In these vehicles I think you need to get under the car to do it though so you need to have vehicle elevated on ramps or at shop. Here are steps I would take before costly compressor replacement: 1. Go to car parts store and buy A/C charging hose, pressure gauge, 2 cans of oil charge and 1 can of refrigerant. All this for about $30-$35. 2. Start car and turn A/C ON at max cooling. 3. Let run for a few minutes and then connect pressure gauge to the low pressure side service port. Record pressure reading. The pressure is ambient temperature dependent but the pressure gauge should have an area marked with green where the pressure reading should be at. 4. Use one of the oil charges, i.e. charge the A/C system with oil. 5. See if the oil charge helps any. One of the ways the noise from tensioner occurs is that the compressor could be hard to turn, i.e. low oil lubrication could cause the compressor run a little bit tight and at each piston compression stroke could cause drive belt tension change and start bouncing the tensioner that then causes the noise. 6. If problem does not get better let some refrigerant out. This would be necessary if slugs of liquid refrigerant enters in the compressor. No liquid should enter the compressor as liquids do not compress. Let out fairly big amount of refrigerant checking pressure at times and see if it helps. If the belt tensioner is broken you might need to have it fixed before you can definitely tell if your noise problem has improved but even with broken tensioner you should hear a difference. After letting all that refrigerant out add the other oil charge in the system to make sure you have enough oil charge in it. If you happen to drain the system low enough so that the cooling performance goes bad then use the can of refrigerant to re-charge the system to point where cooling is good again. If oil charge and lowering refrigerant level in the cooling system do not help you might be facing that $1300 repair cost. But, for making sure you are not spending all that money just because your compressor is running on low lubrication or the system is over charged (liquid entering compressor) the above explained less than $40 trouble shooting procedure might pay off. There is another lower than $1300 cost repair to try before replacing the compressor if the above explains oiling/charging does not help, the expansion valve replacement. Cooling system working principle is as follows: Compressor increases gas refrigerant pressure to a very high level. With this the temperature of the high pressure refrigerant also gets very high. When this high pressure and high temperature gas enters the condenser (at the radiator at front of car) it turns into liquid form when the heat is removed (air flow cools it down). Now at liquid form and still under high pressure the refrigerant flows thru expansion valve. This valve simply is a fixed size hole in the tubing and it separates (like the compressor) the high and low pressure sides of the cooling system. The liquid refrigerant turns in gas form after the expansion valve and causes cooling in the evaporator element, which the air is blown thru inside the car. If the orifice of the expansion valve would wear out and be too large it could let too much flow thru it and cause some liquid form refrigerant to appear in the low pressure side of the system. The expansion valve is very low coast item. I have bought 3 of them in the past for some older cars I had and the most expensive of them was $7 + tax. It could cost perhaps even $20 now. Anyway, the problem is not the cost of the part, it is the work to have it replaced because the whole A/C system must be drained. Expansion valve is located inside the A/C tubing right at the break point in line before that low pressure side service port. While A/C is running you can feel this in temperature of the line as the high pressure side of the expansion valve is hot while the low pressure side is cold. The problem with this work is not the replacement of the expansion valve. It is the re-charging the refrigerant because before that you need to vacuum the system. Vacuuming is necessary because air in the system causes poor performance as air is incondensible gas, i.e. when compressor compresses air it does go to high pressure with high temperature but it does not turn in liquid form in the condenser but remains in gas form and circulates back to compressor taking room from the refrigerant to be compressed. But, you could change the expansion valve and then take the car in an A/C shop just for vacuum and charge. Arrie
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Is there not anyone else with the same problem on a newer model Tahoe? Our 2007 Tahoe has fluctuating fan speed on the ac. It seems especially worse on the middle speed settings. I will be driving along (or sitting at an intersection) and the speed will suddenly go up or down for a few seconds. NOBODY else has this issue? I took it in twice to the dealer and each time they said the system was fine. I took it back a third time and they said the aspirator was bad. However the problem continues.
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