What did you do to your NBS GMT800 Tahoe/Yukon Today?

[mattbta]

I tried my hand at fine tuning the A/C charge now that temps have approached 90 degrees here in Texas. I can't seem to figure out the best way to gauge how much refrigerant I should add (I know, I should be measuring by weight but we're long past that unless I want to evacuate, vaccum, and recharge from scratch which I'd like to avoid). Should the fan be blowing on high, or on low when I'm reading pressures? Should I have a shop fan blowing across the condenser, or spraying with a hose, or leave it completely alone and let the vehicle pull air across it, unassisted?

I can't seem to get it much colder than 50 degrees from the vent with ambient temps around 75 and humidity around 70%. I think the old girl is capable of better cooling, but maybe based on her age it's time for a new condenser since I'm sure after a quarter million miles, the OEM is likely not as efficient as it used to be.

Curious to see where you get. Mine had both ports replaced (within a week of each other) last summer which required evac/vac/refill 2x. I'm skeptical because prior to this, it would push 40* all the time. Now it barely breaks 50* after sitting in the sun and driving 20 min or so. I brought it back to the shop and they inspected and didn't observe a leak but I wanted to know the levels. They wanted to charge me a service fee to evac and refill again but I declined as it may need further work later.

Do you have gauges for checking pressure? Might need to drop by once we get more info on the "how". .

 

[clandr1]

Curious to see where you get. Mine had both ports replaced (within a week of each other) last summer which required evac/vac/refill 2x. I'm skeptical because prior to this, it would push 40* all the time. Now it barely breaks 50* after sitting in the sun and driving 20 min or so. I brought it back to the shop and they inspected and didn't observe a leak but I wanted to know the levels. They wanted to charge me a service fee to evac and refill again but I declined as it may need further work later.

Do you have gauges for checking pressure? Might need to drop by once we get more info on the "how". .

Haha, yep - bought these back in 2015. Will be happy to share lessons learned if/when I figure this out.

MOUNTAIN 8205 R-134a Brass Manifold Gauge Set with Couplers https://a.co/d/87JBRRm

 

[Sam Harris]

Haha, yep - bought these back in 2015. Will be happy to share lessons learned if/when I figure this out.

MOUNTAIN 8205 R-134a Brass Manifold Gauge Set with Couplers https://a.co/d/87JBRRm

Swiped up.. thanks for helping me spend money.

I’ll have to use my thermometer later, to see what kind of temps I’m getting, for comparison.

 

[Tonyrodz]

Swiped up.. thanks for helping me spend money.

I’ll have to use my thermometer later, to see what kind of temps I’m getting, for comparison.

You should get this too Sam.
https://a.co/d/ereUoFL

 

[Sam Harris]

Just picked up the kiddo from school.
Ambient Temperature: 78°
Relative Humidity: 70%

I read between 49 starting the drive from a parked idle (in garage), to a low while cruising of 40.6, but wasn’t able to get a picture while driving. Lol
Around 41-43 while idling at a stoplight:

I wish my home A/C worked that well! It’s around 49 at about a mid-house vent.

 

[clandr1]

You should get this too Sam.
https://a.co/d/ereUoFL

I usually "rent" them from AutoZone or O'Reilly Auto Parts (rent = buy, then return for full refund when I'm done).

 

[mattbta]

Just picked up the kiddo from school.
Ambient Temperature: 78°
Relative Humidity: 70%

I read between 49 starting the drive from a parked idle (in garage), to a low while cruising of 40.6, but wasn’t able to get a picture while driving. Lol
Around 41-43 while idling at a stoplight:

I wish my home A/C worked that well! It’s around 49 at about a mid-house vent.

I haven't used my IR, yet. The shop did and claimed 38* but I didn't see it. I have one of those old man thermometers stuffed in the vent. THIS PIC IS BEFORE MY LEAK/VALVE REPLACEMENT. Best I've seen lately is 42* but that's after pulling out of the garage. Usually around 50*

 

[Sam Harris]

I haven't used my IR, yet. The shop did and claimed 38* but I didn't see it. I have one of those old man thermometers stuffed in the vent. THIS PIC IS BEFORE MY LEAK/VALVE REPLACEMENT. Best I've seen lately is 42* but that's after pulling out of the garage. Usually around 50*
View attachment 399489

Lol. I’ve got several of those, and initially, looking at my home temps, I was using my ThermPro, which is super accurate. But I got lazy, standing there with my arm in the air.. so decided to go with the IR.

 

[Sam Harris]

I haven't used my IR, yet. The shop did and claimed 38* but I didn't see it. I have one of those old man thermometers stuffed in the vent. THIS PIC IS BEFORE MY LEAK/VALVE REPLACEMENT. Best I've seen lately is 42* but that's after pulling out of the garage. Usually around 50*
View attachment 399489

Brrr!! Damn, that’s frosty!

 

[ncalvo]

Brought my ac low side pressure up to 55# while it was 88deg outside and she's blowing ice cold again I am happy. My leak test was good to go last time I did major work on the system but it seems I still have to add half a can to a full can of 134 yearly.

 

[ncalvo]

I tried my hand at fine tuning the A/C charge now that temps have approached 90 degrees here in Texas. I can't seem to figure out the best way to gauge how much refrigerant I should add (I know, I should be measuring by weight but we're long past that unless I want to evacuate, vaccum, and recharge from scratch which I'd like to avoid). Should the fan be blowing on high, or on low when I'm reading pressures? Should I have a shop fan blowing across the condenser, or spraying with a hose, or leave it completely alone and let the vehicle pull air across it, unassisted?

I can't seem to get it much colder than 50 degrees from the vent with ambient temps around 75 and humidity around 70%. I think the old girl is capable of better cooling, but maybe based on her age it's time for a new condenser since I'm sure after a quarter million miles, the OEM is likely not as efficient as it used to be.

Maybe this will help you if you haven't peaked inside at your evaporator. Try cleaning it up, the gunk and growth and fouling could severely restrict the heat exchange. Then grab some evap foaming cleaner.

03 Tahoe Cabin Air Filter Retrofit + Clean Evap

Last september I replaced my ac compressor, all easily accessible hoses and lines, the orifice, dryer, sensors, pulley, belt and clutch fan. System was working well through the mild florida winter. Spring comes around and continues to get hot and humid and I easily can tell my system is not...

www.tahoeyukonforum.com

I do not think changing your condenser will help but I could be wrong. The way I charge my AC is just with a low side gauge/can, front and rear ac on full blast while parked.

 

[Keviebear86]

Since we are on the subject of AC work, how many people have tackled replacing the rear evaporator core and lines? I just ordered a kit from autocoolingsolutions.com and I want to know if its a one day job or am I breaking out the top shelf whisky and spending a weekend in the garage?

 

[RAMurphy]

@Rocket Man tackled some significant AC work back there. Pretty involved. It's in his build thread.

 

[Sam Harris]

Since we are on the subject of AC work, how many people have tackled replacing the rear evaporator core and lines? I just ordered a kit from autocoolingsolutions.com and I want to know if its a one day job or am I breaking out the top shelf whisky and spending a weekend in the garage?

Seems like a royal PITA. I’ve previously taken the rear clamshell apart, to replace a flapper, but the numerous parts inside all came out of alignment, causing it to be impossible to reassemble while in the vehicle. I later purchased a new clamshell assembly, to make my life easier, but it’s sitting in a box untouched. Not an enjoyable job… I may even buy the block off plate and be done with it.. we will see. Having these new puppies, I’ll probably want the rear A/C fully functional.

 

[Keviebear86]

Seems like a royal PITA. I’ve previously taken the rear clamshell apart, to replace a flapper, but the numerous parts inside all came out of alignment, causing it to be impossible to reassemble while in the vehicle. I later purchased a new clamshell assembly, to make my life easier, but it’s sitting in a box untouched. Not an enjoyable job… I may even buy the block off plate and be done with it.. we will see. Having these new puppies, I’ll probably want the rear A/C fully functional.

The Mrs. wants the kids to be comfortable on long road trips. Thinking that might be the deciding factor for me. I believe I have the know how to do it, hopefully it doesn't "hurt locker" me.

 

[latvius]

I've done it, its not that bad. The EASIEST way is to take the whole assy out then take the shell apart. I took the top part off of the shell while it was in and it was a real PITA trying to get to all the clamps that hold the two shell pieces together. You will have to disconnect the A/C lines as well and you will need to vacuum and put in the freon after. If it was me doing it I would buy a new clamshell as it comes with a new blend door. I also am in the South so I had no problems with rusted together parts.

 

[Rocket Man]

Since we are on the subject of AC work, how many people have tackled replacing the rear evaporator core and lines? I just ordered a kit from autocoolingsolutions.com and I want to know if its a one day job or am I breaking out the top shelf whisky and spending a weekend in the garage?

I did it on my 02 recently. One thing I found out is even here in the PNW where we don’t use salt on the roads, there’s no way those rear AC lines will come off. Mine were seized onto the evaporator core. Plan on breaking or cutting them off. Also, the quick connects for the heater lines- you won’t find OEM ones and they’re 90* angles. I ended up buying Dorman ones. The lines themselves are fairly easy. I cut the old ones out in pieces, and the flex lines went right back into the same clips that held the old ones. I know they say you can just tie strap the new onto the old, but nah. Here’s a link to the place in my build thread where I decided to not block the rear off and replace the parts instead. You’ll want the expansion valve also.
Edit: and yes, remove the rear assembly completely to replace the parts inside.

Rocket Man's 02 Denali Build Thread AKA "THE BEAST"

Mr @randeez left us…. That tool…;) :happy175: :happy175: :happy175::happy175::happy175::happy175::lol2: Yeah he got sick of this tinkering sht and jumped ship, bought a new truck.

www.tahoeyukonforum.com

 

[Keviebear86]

So now the next question is...To remove the factory fender flares or not? After fixing all the rust and the body looks much better, I'm questioning keeping the textured fender flares.

 

[Sam Harris]

So now the next question is...To remove the factory fender flares or not? After fixing all the rust and the body looks much better, I'm questioning keeping the textured fender flares.

Hard to offer an opinion without pics..

 

[mwilson62000]

GMT900. Ordered all ACDelco parts for 2008 Yukon XL from Rockauto today.

Parts starting to arrive!