What did you do to your OBS GMT400 Tahoe/Yukon Today?

[TheAutumnWind]

Out with the old in with the new.

Looks like these are unpainted plastic. Ive heard they go grey after awhile. Ill have to paint them at some point i guess. The whole truck needs paint tho so nbd

 

[96-2D-Hoe]

Replaced the orifice tube and charged up the AC. AC now not blowing cold enough to keep the car cool on just a warm day. From a couple searches for 'black sludge in orifice tube' seems I have 'black death/goo' in my AC system and it all needs replacing /or flushing. The HT6 compressor is leaking from the joint in the center and I'm guessing the previous owner, or the stealership, put some kind of leak sealer in the system that has deteriorated. On the plus side, all the UAC parts to replace everything except the evaporator coil, and a flush kit to clean the evap are only $350 delivered from RockAuto. Must fix it, but right now it's another job for another day.

 

[96-2D-Hoe]

Looks like these are unpainted plastic

Hard to tell form the pic but they look basically the same as my polished plastic OEM sport mirrors.

 

[TheAutumnWind]

Replaced the orifice tube and charged up the AC. AC now not blowing cold enough to keep the car cool on just a warm day. From a couple searches for 'black sludge in orifice tube' seems I have 'black death/goo' in my AC system and it all needs replacing /or flushing. The HT6 compressor is leaking from the joint in the center and I'm guessing the previous owner, or the stealership, put some kind of leak sealer in the system that has deteriorated. On the plus side, all the UAC parts to replace everything except the evaporator coil, and a flush kit to clean the evap are only $350 delivered from RockAuto. Must fix it, but right now it's another job for another day.

View attachment 220066 View attachment 220067 View attachment 220068

The next big hurdle i will have with this truck is getting the a.c. working. Gotta get that done before triple digits... I look forward to seeing more on your repair. Hope it goes smoothly

 

[96-2D-Hoe]

The next big hurdle i will have with this truck is getting the a.c. working

If your compressor clutch kicks in, even for just a second when you turn the AC on you're in good shape. Means there's still some refrigerant in the system and it probably just needs a charge up. The refrigerant shouldn't leak out at all but it often does. Where it leaks from it normally leaves oil as it is carried with the gas. If you lost gas check all the connections to see if you can see an oily mess on one of them and that will be the leak. You can verify it with soapy water, and look for bubbles.

Replacing all the parts is as simple as unbolting the old ones and putting the new ones in their place. But if you do that or have to open your system you're going to need a manifold gauge and a vacuum pump. If it's just opened up for a moment to swap out the orifice tube you can just purge it by letting some gas through to force out any air, which is what I did. You could also replace the parts you need and go to an AC shop to have them evacuate and charge the system for you. The refrigerant charge should be under the hood on a sticker, or on the drier if it's the original. Mine takes 3lbs refrigerant. Be glad to answer any questions I can if you have any.

I must do mine before it gets hot too. Been a bit sick lately and the maintenance jobs are backing up. When I do it I'll take pics as I go. Here's the parts list for my truck



PS
$350 is still a lot of money, but I was quoted almost $200 from a shop just for refrigerant recovery. Thankfully if I wait long enough mine will completely leak out from the compressor. At a guess you're probably looking at close to $1k for a shop to do a complete overhaul.

 

[liquify33]

Replaced the AC blower motor.

Delco works a ton better than the aftermarket one it replaced. It moves so much air my hair was blowing like a commercial, and I’m bald!

 

[Tonyrodz]

Replaced the AC blower motor.

Delco works a ton better than the aftermarket one it replaced. It moves so much air my hair was blowing like a commercial, and I’m bald!

 

[TheAutumnWind]

Had 45 mins to screw around today. Swapped in some 2" maxtrac lowering shackles. No more crazy rake. Grease zerks are nice. No poly bushing squeaks or anything.



Still definitely needs more low but this will do for now.

Got some better bulbs suggested by candlepowerforums. Drivers side has the new xtreme power one, previous basic 9006s look brand new. Not a huge difference, but noticeable. Hopefully relays(coming this weekend) help too. Eventually ill do the big 3 since im only ever seeing a max of 14v. Needs a better alt at some point too.

Cheapo Relay kits came in. Its 18g power wire lol. Im gonna swap the red side for some 10g ive got laying around. Not sure if ill swap all the grounds yet. Oh well worth it for making it easier on myself i guess. I needed the 9006 males and females and whatnot anyways.

 

[TheAutumnWind]

Couple little things today

"Big 2" upgrade. Battery to body ground (1/0 100% ofc) and alt to battery positive (2 gauge 100%ofc) so far. Noticeable voltage improvement at idle. Engine block to battery negative looks decent enough but maybe ill do that too. Looking for suggestions for the third part of the big 3 i guess.

Also put on one of those $25 tailgate led strips. I added the loom, would have happily pad a few dollars more for one that was already loomed. We'll see how long it lasts but it sure looks bright.

 

[TheAutumnWind]

Big 2 plus headlight relay plus philips xtreme 9006 seems to have made a noticeable difference in headlight output. Worth the efforts id say.Factory oem 94 headlamps.

Note: first pic actually has the new 9006 xtreme bulb on the drivers side already. Stock wiring. Original standard 9006 on the passenger side.

 

[Squirrelsmith]

Big 2 plus headlight relay plus philips xtreme 9006 seems to have made a noticeable difference in headlight output. Worth the efforts id say.

Note that the very first pic actually has the new 9006 xtreme bulb on the drivers side already. Stock wiring. Factory oem 94 headlamps. Original standard 9006 on the passenger side.

View attachment 221003 View attachment 221004 View attachment 221005

I've been thinking about doing something with the headlights. My wife asks if they are on every time haha

 

[TheAutumnWind]

I've been thinking about doing something with the headlights. My wife asks if they are on every time haha

From factory are pretty disappointing. Lighting is typically one of the first things i upgrade. Improving grounds and power wire in conjunction with adding a decent relay setup made a big difference for sure.

 

[liquify33]

From factory are pretty disappointing. Lighting is typically one of the first things i upgrade. Improving grounds and power wire in conjunction with adding a decent relay setup made a big difference for sure.

What did you change on the relays?

 

[TheAutumnWind]

What did you change on the relays?

Not sure exactly which part you are asking about so ill try and hit it all.

the stock setup is sad. Power goes from battery to switch in dash and back out to lights. Probably 20 feet of 18 gauge wire. Typically around 11 to 12v max at the bulbs. There is an exponential loss of lumens with voltage so dropping from 14.x volts rated output to lets say 12v is like a 50% lumens loss. Thats horrible.

Anyways i purchased a cheap relay kit which acts as a remote switch and provides power directly from the battery. In retrospect i would have gone another route. It was 18g wire, so I used the male and female 9006 plugs basically. I had hd relays, 12g inline blade fuse sockets and 10g wire laying around so i replaced all the positives on that relay setup with a minimum of 12g wherever possible. The grounds are short runs so i didnt bother. Its possible that could be improved.

Ill likely replace the sockets with nokita sc06 units which use a 14g wire and are not plastic but ceramic. Id be surprised to see a return on investment there but id get peace of mind i suppose.

 

[TheAutumnWind]

I've been thinking about doing something with the headlights. My wife asks if they are on every time haha

Do it. If you dont mind cutting your headlight wires you could accomplish this quite inexpensively and easily. Need a relay and relay harness. An inline fuse holder and a few feet of 14g wire atleast.

 

[liquify33]

Thanks for that write up. I’ll have to check my bulbs/wiring and voltage but no complaints here on visibility.

 

[TheAutumnWind]

If your compressor clutch kicks in, even for just a second when you turn the AC on you're in good shape. Means there's still some refrigerant in the system and it probably just needs a charge up. The refrigerant shouldn't leak out at all but it often does. Where it leaks from it normally leaves oil as it is carried with the gas. If you lost gas check all the connections to see if you can see an oily mess on one of them and that will be the leak. You can verify it with soapy water, and look for bubbles.

Replacing all the parts is as simple as unbolting the old ones and putting the new ones in their place. But if you do that or have to open your system you're going to need a manifold gauge and a vacuum pump. If it's just opened up for a moment to swap out the orifice tube you can just purge it by letting some gas through to force out any air, which is what I did. You could also replace the parts you need and go to an AC shop to have them evacuate and charge the system for you. The refrigerant charge should be under the hood on a sticker, or on the drier if it's the original. Mine takes 3lbs refrigerant. Be glad to answer any questions I can if you have any.

I must do mine before it gets hot too. Been a bit sick lately and the maintenance jobs are backing up. When I do it I'll take pics as I go. Here's the parts list for my truck

View attachment 220208

PS
$350 is still a lot of money, but I was quoted almost $200 from a shop just for refrigerant recovery. Thankfully if I wait long enough mine will completely leak out from the compressor. At a guess you're probably looking at close to $1k for a shop to do a complete overhaul.

Added some refrigerant. Compressor kicks on and off now. Seeing low pressure on the high side like 115 psi. Gotta find my leak.

 

[96-2D-Hoe]

Added some refrigerant. Compressor kicks on and off now. Seeing low pressure on the high side like 115 psi. Gotta find my leak.

If you've put plenty refrigerant in, like 2-3 lbs, and you're only getting 115psi on the high side your compressor has had it, and you should also be getting a high reading on the low side. Most likely cause of leak is the joint in the center of the compressor itself. The HT6 is known as a 'belly leaker' for that reason

 

[Squirrelsmith]

Hooked up a 4 prong for my trailer. I couldnt believe all the wires were the untouched after 20 years ziptied behind the bumper

 

[TheAutumnWind]

If you've put plenty refrigerant in, like 2-3 lbs, and you're only getting 115psi on the high side your compressor has had it, and you should also be getting a high reading on the low side. Most likely cause of leak is the joint in the center of the compressor itself. The HT6 is known as a 'belly leaker' for that reason

Damn. Im really hoping its a fitting or hose or something. Not seeing anything obvious though and its definitely leaking somewhere... Ill have to look closer at the compressor. I'm surprised to have this problem on such a low mileage truck despite its age. Its only got 65k miles...