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.