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
#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.
#95 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [natale]
Aug 28, 2008 (4:22 am)
We finally gave up. Fall is almost here and we won't need the AC shortly. We snapped 2 tensioners right from Chevy. They put them on, put on the belts, turned on the truck, turned on the AC, hit the gas the tensioner broke. Threw a piece right off. The only thing that anyone can come up with (and 3 guys have all come up with the same thing) is that the Compressor is gone and when we step on the gas, we're putting too much pressure or torque (it's early, and it's been awhile since it was explained to me) and that's snapping the tensioner.
Basically, we were looking at at least $1500 in repairs to possibly fix the issue on a truck that's worth $5000 and needs new plugs and wires and new tires. $3000 total. I just can't do that right now. So, DH can suffer his 2.5 mile commute w/o AC for a few more weeks.
Good luck figuring out the issue. I'll check back to see if anyone does find a resolution. The guy who did most of the work for me thinks the tensioner is a piece of crap and Chevy should have made it heavier. FWIW.
#96 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [waltherchic]
Aug 28, 2008 (4:45 am)
Unplug the compressor power wire. If the driver turns on the defroster in the fall/winter to defrost the windshield, that will turn on the compressor to get the humidity out....and you'll break another tensioner on the road somewhere.
#97 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [natale]
Aug 28, 2008 (6:04 am)
Natale, Sorry to hear of your losses,..You've had a tough Month. Hopefully i can figure it out for ya ,with Arries help,.. It did get better when i lowered the pressure to 35..Im gonna drive it today and see if the air stays cold and see if the noise comes back.ill let you know...Just waiting for arries advice on wether to lower further before adding oil and freon...Its definately not the tensioner, i put on a new one and it made the same noise right away, so i returned it to the parts store..Thanks
#98 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [treedog]
Aug 28, 2008 (1:56 pm)
Hi there treedog,
I had not heard back from anybody regarding the issue until today.
I am visiting in Europe and have not been able to connect to internet. This is the country with Autobahns and it feels kind of good driving 140 MPH in a car that is made for driving fast...but that is another topic.
If your A/C still blows cold I would let some more refrigerant out. You can do this until you see a drop in the A/C efficiency and then add some back until it works ok again. But before letting more out you might want to make sure you have enough oil in it as oil is lost when you let refrigerant out.
There is another thing to consider too, which I am thinking to do myself to my own Tahoe...replace the expansion valve.
Expansion valve can be a problem as it has a very fine mesh screen with it. Over time the compressor wears and all of the metal dust that it spits out is meant to be caught by this screen on the expansion valve. Well, if this screen gets plugged too much it starts to restrict coolant flow thru it and this could be causing some trouble.
The job includes vacuuming the A/C system before re-charging it.Vacuuming is possible to perform at home too. I have done this in the past a couple of times and it works fine.
For vacuuming the A/C system you need to purchase another charging hose and then cut off the end that screws to the refrigerant can. Then you find a vacuum connection in your car's intake manifold (there usually are plenty of those) and see what size hose you need to get to connect to one of these ports. Then you get a proper size hose and connect it to the charger hose end that you cut the refrigerator can connector off. Now you have tools to vacuum your A/C system before re-charge.
You turn off the A/C system (it should not run without refrigeranr anyway but to make sure turn it off) and start car and run it on idle. When idling the engine generates very high vacuum inside the intake manifold. Some cars over 24". When you connect the hand made hose to the A/C system service port and then the other end to the intake manifold port you will vacuum the A/C system very well. You have it "vacuuming" 15 minutes and it is pretty empty.
After about 15 minutes disconnect the hose from the service port before turning off the engine. Now you are ready to re-charge the A/C system. You will start with a can of oil charge. It will go inthe system without running the engine as the vacuum in the system will pull it in. Then you start with a can of refrigerant and when that stops going in you will need the help of the compressor, i.e. turn on the A/C system for max cooling. This probably will not start the compressor as the coolant level is still so low in the system. To make compressor run you need to short the two wires on the harness that connects to the pressure sensor that is mounted on the side of the dryer bottle.
A new expansion valve is very low cost item. Last one I bought for my Dodge Ram tryck cost $6 or something like that. Expansion valve is located inside the tubing where there is a union on the line just before that dryer bottle. If you run the A/C before the job you can feel the line for temperature as before the expansion valve it is hot and after the valve it is cold.
#99 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [arrie]
Aug 29, 2008 (5:29 pm)
Hey Arrie , Glad your having fun...I have a European friend that would love to bring his BMW back from Florida and drive it on the Autobahn...
O.k im at 35# refrigerant now, so should i drop it to 25 and add a can of oil and then some refrigerant if it needs it?..Or just put in some oil now at 35?..(My oil cans say they have 2 ounces of oil and 2 ounces of refrigerant)..Id like to try one of these options first before i vacuum the system .Right?.
It should have plenty of oil because before i drained it i added a can to see if it would help...then after it didnt help, i added another can..and it still didnt help...And then it was in the danger zone .(above 60)..so i had to let it out anyway...so i backed it down to 35..
Then what about the oil and freon going into the vacuum line of the intake.That wont hurt anything?.What about a regular shop vac adapted to fit the hose from the end i cut off?
If the air is ice cold at 35 with a ambient temp of 90 ..Then would you still think the expansion valve is restricted?..Seems like it would be noticably warmer if it was restricted since at 90 degrees it recomends 45-55.
I was told to use the 150 vicosity oil..And that the 100 was ford and 46 was dodge..Am i using the correct oil?..Thats what they said at Autozone anyhow..
Thanks for all your time. I really apreciate it
#100 of 372 Re: AC / Heat Noises 2002 Chevy Tahoe [treedog]
Aug 30, 2008 (4:50 am)
If you added two cans of oil at first then I think you can let some more refrigerant out and like I said you will see when you are too low as your cooling will start suffer.
As your compressor already is years old meaning it is not the tightest one I would use higher viscosity oil. It's like with old car engines. High mileage engines benefit from higher viscosity oil as fit between piston and cylinder is not that tight any more.
And make sure you run also the rear seat A/C as it works from the same compressor when you evaluate if it still blows cold or not..
Vacuuming the A/C system using a intake manifold port should not harm anything in the engine. I think the only component that could get harmed from the A/C system oil is the MAF sensor, but this sensor is mounted right after air box in the ambient pressure environment. The only sensors that are in the engine system that would see the A/C oil are the O2 sensors but they see engine oil anyway so I don't think A/C oil would hurt them especially because very little of it will be coming out from the system when you vacuum it.
Shop vac will not provide any real vacuum that would be sufficient for A/C system vacuuming. You either need to use a specially made A/C vacuum, like people working on home systems use (or car systems) or use the car engine vacuum. I have done this on a Lincoln that I had many times when I had problems with seal leaks and also with my Dodge RAM truck when I changed the expansion valve and dryer in its system.
Have you noticed any difference in fuel mileage after you dropped the A/C system pressure?
Why I mentioned the expansion valve as a possible problem is that it can cause it two ways. Either the screen of it can get plugged or the orifice wears out to too big opening.
If it gets plugged it can cause over pressure on the compressor output side and if the compressor is equipped with an over pressure port it can make noise when this port open up and re-circulates refrigerant back to intake side of the compressor. In my Dodge the over pressure valve spits the refrigerant out, which was a clear indication of my expansion valve being plugged, like it was when I finally changed it.
If expansion valve wears to too big opening it can let too much liquid refrigerant thru it on the intake side of the compressor, which is not good. Liquid does not compress so it can cause over pressure in the compressor and be the cause for the noise.