What did you do to your NNBS GMT900 Tahoe/Yukon Today?

justchecking said:

I really don't think you needed to change that bad lifter. JUST kidding, read on. So, I was picking up my daughter a while back at the airport and as I pulled into the cell phone lot I see another 2011 WHITE Suburban LTZ just exactly like the twin of mine backed into a spot in the back row. So me being me I backed in right next to it on their drivers side. I see the driver dinking on her phone for a while, then I see the recognition as she sees my bumper and looks along the car and looks over at me. So I roll down my window and we had a very nice conversation about our Suburbans. They bought it new and have about 205,000 miles on it. No issues ever and change the oil whenever the oil monitor says to. Best car they ever had and going to keep it forever. Finally she gets a text from her husband that he is ready to be picked up. She fires up the Suburban - TICKYTICKYTACKTACKTACKYTICKYTACKTACKTACKTACK!!!! Then she gave me a friendly wave and off she went!
So changing lifters may be overrated. No pictures because I already was afraid she might think I was a Suburban stalker. I do wish I had a video though.

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Maybe it was a diesel, lol

Chevymec said:

20756891,GM0817558 Power Folding Door Mirror Motor Left/Right Compatible with 2007-2013 GMC Yukon Sierra, Chevrolet Tahoe Suburban Silverado, Cadillac Escalade Replace GM0817558,20756891 https://a.co/d/00DhuMff

$49. I was a few bucks off.

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How is it left/right compatible?

Cleaned up and hitting the road. Stock bulbs suck.

Ok you fart smellas, uh, I mean smart fellas, someone help a brutha out please.
That means u @randeez nuts….or anyone that knows anything about automotive a/c.

13 hoe lt with rear air and digital display. Never had a problem with a/c in this thing since new.
Warm air out of front and rear vents, kinda cool but not really. It was a slow decline in coolness, as in, i could tell the air wasn’t as cold as it used to be and now its to the point where its just warmish but not exactly hot.


So, about a month ago i was driving and i noticed some frost, haze, cloudiness coming out of the 2 vents above the radio… still cold tho, got in a few days later when my daughter was driving and noticed it wasnt as cold looked at the temp and she had it on 64 or 65 and medium fan speed so i dumped it down and i still thought it wasn’t as cold as it should be. (Im the only that uses auto in all my vehicles…. In my mind… set it and forget it.. you dont need to lower/raise fan speed or if you’re cold raise temp a few degrees or hot dump it down…)

Didn’t think about it for a week or 2 because temps went back to normal after being hell on earh here in NY for a week in mid June.

Got to look at it last weekend dumped it down to lowest setting, recycled air and fan speed on high doors open …. noticed the high side line past the large nut that goes into the evaporator next to the accumulator was all iced up. I heard compressor kick on then off so I figured i have a small leak (since compressor was coming on and it was still kinda cool). In my garage i had one of those autozone a/c single low side gauges from a buddy that gave me a few cans and some other stuff while cleaning his garage. I hooked it up and it said it was fine (no numbers, just green, blue, yellow and red.)
When compressor was on the gauge went to normal (blue i think) when it cycled off it shot up to red and cycled like that a few times. I have a real set of gauges in my basement but I was being me and being lazy so I haven’t broken them out yet.

This is when i noticed is was cycling quickly… as in every 30-45 seconds it would cycle on/off and then i realized the electric fans weren’t screaming at me like they normally do when its full on hell here and a/c is at its max.

Heres what ive done since then:

-Ordered and replaced the pressure switch
-Cycled the digital display from hot to cold
(on auto and separately for each side) a few times and heat works as it should
-blower motor fan speed is normal and all vents work as they should
-replaced cabin filter
-physically powered on rear seat controls, cycled them and everything works as is it should
-pulled the pigtail off the pressure switch and jumped it to try and get the compressor to go on and stay.. nothing but thats when the electric fans came on full blast…. and with that i gave it a check engine light with reduced engine power and stabilitrac and traction control off msgs but I’ve cleared that and code was something like signal wire bad reading or some crap like that so thats gone.
-and we are dripping condensate… either that or the evaporator is melting from being iced up

So this is where im at.

In a little bit im going to grab my gauges and see what kinda of pressures there are but im thinkn either the rear lines or compressor are starting to go and maybe something is clogging the orifice up by the high side line by the freezing nut..(lol) or something is going on with the e fans….. or maybe im completely off and its the digital control or blend door….
I don’t know… anyone with any insight please clue me in.

Thanks in advance…. Any and all ideas are appreciated

high side can't or at least shouldn't freeze without breaking laws of physics or something.


classic low on freon. like a lot low. if you have a high level scanner that can read havc data and codes, you can see all the pressure from there. fans are controlled by high side pressure, you're so low the high side can't come up to turn the fans on max.


add like 2 cans and start looking for leaks. compressor belly or, the high side valve most likely. gm can't make a high side valve seal to save it's life. brand new ones out of the bag leak. once replaced, I cap them, fill thru the low side and pray they hold. Just putting a gauge on them cause them to leak. it's very annoying.

j91z28d1 said:

high side can't or at least shouldn't freeze without breaking laws of physics or something.


classic low on freon. like a lot low. if you have a high level scanner that can read havc data and codes, you can see all the pressure from there. fans are controlled by high side pressure, you're so low the high side can't come up to turn the fans on max.


add like 2 cans and start looking for leaks. compressor belly or, the high side valve most likely. gm can't make a high side valve seal to save it's life. brand new ones out of the bag leak. once replaced, I cap them, fill thru the low side and pray they hold. Just putting a gauge on them cause them to leak. it's very annoying.

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Large line isnt the high side?

j91z28d1 said:

super interested in what you find if they let you see the lifter. you caught it so early. I wonder what they failure point is.

I don't remember, but I'm guessing it was a afm cyl? if it didn't hurt the cam, I'm guessing not the roller or the trays. it wasn't ticking loudly, so I feel like the afm part didn't release and get stuck. that kinda only leaves the normal plunger part of the lifter.

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1/5/7 are afm lifters (on bank 1), couldn't hear anything at idle only at around 1100rpm, 1500rpm+ no noise
when you could hear it, it sounded like 2-3 loose rods in tubes rattling around is the best way to explain it, but wasn't loud.
even though I drive like a crazy person and blast my music loud I pay attention to how my engine sounds, so if I start to hear something different I turn everything off and
listen, sometimes the best way to listen is to drive along a wall or barrier because it reflects the sound, like behind a shopping center or down a alley way
normally my vehicle is dead quiet so it's easy to tell when something is abnormal
sometimes I just pop the hood, start it up and listen to it for while, just because I know that I drive it beyond what most people do
funny though that in the last 30+ years this is the first time I have ever had a internal engine problem with a GM, broke plenty of other stuff but the engine has always held up
not counting knock sensors or water pumps, the worst I ever had was a timing gear wear out and jump timing on a old 350 in a 1980 trans am, the gear they used was coated with plastic and when that worn out the chain would be loose and in my case it slipped and jumped time, easy fix in general terms.

I don't have the same ac system, you'll have to trace the lines.. high side comes from the compressor to the condenser in the front, from condenser to the evaporator under the dash, there it gets cold, exit the evaporator then to back to the compressor again. normally you can end up with the line that exits the evap getting cold.


I mean now that I think thru it, I don't know where the orifice tube is located, since you have rear ac, I'd have to look up where it's at. in a weird case if it's right at the exit of the condenser, it could possibly get cold before making it to the evap inside. they normally the to keep the tube close to the evap so it doesn't take on under hood heat before making it inside.


what did you get for pressures with your gauges. I mean I guess it's possible being a auto system you've got enough temp sensors reading wrong that it thinks it's below 32 degs and is cycling the compressor to keep from freezing up. but I think all that would set some codes, and you cleared some non sensor codes.

definitely put your gauges on it and check, but I think you'll see it pulls down real quick on the low side, cuts compresor and repeat while not getting much pressure(heat) into the high side. slowly add a can and see if it says on longer and longer as dash Temps get colder.

if you can get the low side steady at 40psi with front and rear ac on max and the compressor not cycling. that's about the best you can hope for. most won't hit 40 without the windows rolled up driving.

Doubeleive said:

1/5/7 are afm lifters (on bank 1), couldn't hear anything at idle only at around 1100rpm, 1500rpm+ no noise
when you could hear it, it sounded like 2-3 loose rods in tubes rattling around is the best way to explain it, but wasn't loud.
even though I drive like a crazy person and blast my music loud I pay attention to how my engine sounds, so if I start to hear something different I turn everything off and
listen, sometimes the best way to listen is to drive along a wall or barrier because it reflects the sound, like behind a shopping center or down a alley way
normally my vehicle is dead quiet so it's easy to tell when something is abnormal
sometimes I just pop the hood, start it up and listen to it for while, just because I know that I drive it beyond what most people do
funny though that in the last 30+ years this is the first time I have ever had a internal engine problem with a GM, broke plenty of other stuff but the engine has always held up
not counting knock sensors or water pumps, the worst I ever had was a timing gear wear out and jump timing on a old 350 in a 1980 trans am, the gear they used was coated with plastic and when that worn out the chain would be loose and in my case it slipped and jumped time, easy fix in general terms.

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ready good you caught it early. I'm not sure I'd have picked that up.

when I first got mine it would idle at just the right rpm and sounds like a timing chain slap, I was like nope, not taking that apart till it gets much worse haha. turns out when I did the motor mount it went away, I can only guess it was sitting on the mounts cross pin and rattling just right. funny the noise reminded me of that same old sbc timing gear that was plastic. when I was a kid, my mom had a 76 Caprice, it died one day and got towed in the back yard. once I got older and into cars I ended up taking it apart and found that same thing. all the plastic teeth were gone. replaced that and it ran better than it ever did. that car always had a cough thru the carb if you hit the gas fast from a stop. after replacing the timing set that all went away. the good old days of easy to work on cars.


hopefully they get you fixed up for anyone 100k.

And thats that….. for now anyway…..def a leak but thats for another day... If my lazy butt would have went down to my bsmt to get the ‘correct tool’ i would not have posted a book earlier in this thread…. God im so lazy ….