Last post on Nov 18, 2013 at 7:10 PM
You are in the Chevrolet Suburban & Tahoe
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Chevrolet Suburban, Chevrolet Tahoe, Chevrolet Tahoe Limited/Z71, SUV
#85 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [waltherchic]
Jul 21, 2008 (8:28 am)
You say ...A/C kicks just fine...why do they want to replace the compressor then?
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.
Aug 04, 2008 (12:19 pm)
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.
#87 of 372 Re: HELP [nflguy]
Aug 04, 2008 (2:03 pm)
Is it an automatic climate control system or is it manual?
Automatic system does change fan speed according to temperature reading inside the vehicle.
A sudden change in fan speed can happen for example if the driver's head is located too close to the air temperature "sampler" intake in the ceiling and suddenly changes distance to the sampler. Help for this issue is to set driver's seat lower so that head is not too close to the sampler intake at any time.
Sounds weird but drivers head being too close to this small "speaker looking" air intake can change air temperature entering inside the tube where temperature is measured. This happened to me and I had to lower my seat down from where I first wanted to have it.
Above assumes that the air temperature measurement is made to work the same way as in '04 Tahoe with automatic climate control.
If your system is a manual climate control and has fixed fan speeds and fan speed suddenly changes you have an issue, which must be fan or fan speed controller related.
#88 of 372 Re: HELP [arrie]
Aug 04, 2008 (8:37 pm)
I can have it set to manual or auto. We don't typically use the auto but when we do the same problems happen.
This is a VERY frustrating problem. I'm likely to be out of warranty by the time next summer rolls around so I wanna get this fixed asap.
They said nothing was wrong the first few times they checked it out. The problem got worse and worse until eventually the max air button would click off on it's own even though we were on manual setting. I brought it in again and they said the aspirator was bad (the thing above your head) so they replaced it. Now the max ac button no longer shuts off on it's own but the brief changes in fan speed have returned. I fear it's some kind of electrical issue with voltage problems on the blower resistor. The problem is that dealers rely on the vehicle computer system when deciding if replacing parts is needed. If there is a problem but the computer doesn't show it (via codes) then the dealer won't do anything to fix.
#89 of 372 Re: HELP [nflguy]
Aug 05, 2008 (1:31 am)
Just wait until your warranty is gone and your dealer will find all sorts of issues to repair on your vehicle.
GM is in so deep mess at the moment they cannot afford fixing vehicles on warranty unless they absolutely have to. Issue like yours, if not absolutely repeated at the dealer's service shop and you having witness with you will not be repaired on warranty but as your warranty goes out I can guarantee they will want to change all kinds of parts on it as it will be done on your dime.
I had to trouble shoot and fix my car myself after the first about 2000 miles when fuel consumption went from 18+ MPG to 13 MPG on highway driving. Dealer claimed there was nothing wrong as there were no trouble codes in computer. I found all sorts of problems the intake manifold leak being the biggest one...and whole bunch of improper electrical connections on wire harnesses...
Good luck with yours.
#90 of 372 Re: HELP [arrie]
Aug 05, 2008 (9:57 am)
What year Tahoe did you have the problem with???
#91 of 372 Re: HELP [nflguy]
Aug 05, 2008 (3:40 pm)
I have been buying "little used" 2 - 3 years old cars before as I am kind of a mechanic and fixing cars for me is easy unless it is a computer issue or something like that.
After years saving money I finally was able to consider buying a new vehicle and it sounded so good not needing to work on it. It cost almost $40 000 to get my hands on this Tahoe LT and then all but trouble. And chevy dealer does not do anything to fix it.
Tail pipe looks like it burns a gallon of oil between oil changes, but it did not and still does not burn any oil. It just sent unburned fuel thru tail pipe as engine was not working at the most effective way and biggest problem with this seemed to be intake manifold gasket leak. Believe or not but it has a lot to do with engine performance as leak changes MAP sensor reading, which is part of controlling ignition timing.
Leaking intake manifold gasket also caused rough or jerking idle.
I also soldered almost all wires to the pins at sensor harnesses. I believe the only one I have not done yet is the crank shaft position sensor wire harness and that is because it is not easy to get to. Starter motor has to be removed to gain access to it.
My Tahoe works quite well now and I still get about 18 MPG with 77 MPH speed on highway. I have 94 000 miles on it.
Last scare was coolant level dropping off but it seems to have fixed itself after I poured some Bar's leak fix in it.
#92 of 372 2007 Tahoe AC fan speed problems
Aug 12, 2008 (11:05 am)
Finally last week they said there was a problem. They told me my aspirator was bad and that was causing the blower speed to vary and the max ac to shut off. That fix lasted one day.
I dropped the tahoe off this morning and showed the tech guys how my ac fan speed will go up and down even when parked. They called and said they can't figure it out so they are gonna replace the control head. Well see if it works.
#93 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [arrie]
Aug 27, 2008 (6:53 pm)
Hey Arrie, I never heard anything back from the post you made on july 21st,I was wondering if your information helped the other two (Natale and Waltherchic) i have the same problem with my chevy tahoe...the a/c works fine but i have the same noise ...its not the tensioner...So I added 1 can of oil,...it didnt help me...i let out a bunch down to 35 and my ambient temp was 90...so 45-55 was my range..Right?..should i go lower then 35?....my a/c still blows cold....it seems a little better since i lowered to 35....but still does it sometimes when i rev the engine at idle...just wondering if i should ad oil from here or let more out first?...Whats your opinion? you have been a great help..I really apreciate your knowledge...thanks
#94 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [treedog]
Aug 28, 2008 (3:09 am)
Sorry it has been awhile for you to hear back from me i had two deaths in the family since july 21st. I have not tried what Arie suggested yet in regards to the problem i have with my Heat/AC. In a week or two i am going to be putting it in the shop to get it fixed. I have already changed the belt and tensioner and it still makes that noise i described in my first posting. I am willing to bet it is compressor. After i bring it in i will get back to everyone letting you know what they find.