2004 6.0 NV4500 Tahoe

[Dantheman1540]

Spent several hours last night tracing wires, pulled the entire harness out of it’s wrap, and yanked the fuse box. IIRC the high pressure sensor down by the compressor is not being sent the 5v it needs to function. I traced that all the way back up to the ECU pin 14 (red/blk wire). It’s almost impossible to get the probe into the ECU connector while plugged in so I striped a tiny bit of wire a few inches from the ECU and it’s not sending the 5v. This leads me to believe possibly the ECU has failed, or there is something not being sent to the ECU for it to then send the 5v out.

Going to try swapping ECUs later today but I’m really not all that hopeful it’s gonna do anything. A small part of me wants to hope the weird rich condition during the first minute after startup, the DBW problems this truck has had, and this AC issue might all be the ECU failing but I’m never that lucky.

Last note is the only obvious thing I’ve found is Stud#2* 30amp fuse was blown. Iirc this fuse has blown before and it has to do with trailer wiring, likely unconnected to the AC issues.

 

[Dantheman1540]

This makes no sense but today I spent another several hours messing with the AC and wiring. Finally I decided to revert to the “shake shit and see what happens method” had my laptop propped up on the engine, the engine in and was watching the AC sensor voltage channel as I harassed the wiring. It seemed as though maybe the connector for the high pressure switch was intermittent so I tried all sorts of stuff to get it to fully connect.

I finally gave up and decided to see if one of the other two sensors I had fit better. As soon as I popped the original sensor that was in the Tahoe for the last few months in the voltage jumped up to 4.5 on the channel! I swapped that sensor into the line and boom ac works. Not sure wtf is really the solution but it’s working right now so I call it a win. I have a lot of wire loom to repair tho.

 

[randeez]

This makes no sense but today I spent another several hours messing with the AC and wiring. Finally I decided to revert to the “shake shit and see what happens method” had my laptop propped up on the engine, the engine in and was watching the AC sensor voltage channel as I harassed the wiring. It seemed as though maybe the connector for the high pressure switch was intermittent so I tried all sorts of stuff to get it to fully connect.

I finally gave up and decided to see if one of the other two sensors I had fit better. As soon as I popped the original sensor that was in the Tahoe for the last few months in the voltage jumped up to 4.5 on the channel! I swapped that sensor into the line and boom ac works. Not sure wtf is really the solution but it’s working right now so I call it a win. I have a lot of wire loom to repair tho.

nioce

i ripped about my whole ac system back apart, orifice tube had a little bit of metal on it...maybe a teaspoon worth, wasnt completely blocked. didnt find shavings anywhere else. cleaned out the hoses, blew out the evap in the dash, condenser, chiller. waiting on new driers (cabin ac and chiller) and orifice tube, all to be delivered tomorrow.
i may grab a little more pag oil. no idea how much it needs but i put a couple oz in the compressor but want to add a little to everything when i put it back together

 

[Dantheman1540]

nioce

i ripped about my whole ac system back apart, orifice tube had a little bit of metal on it...maybe a teaspoon worth, wasnt completely blocked. didnt find shavings anywhere else. cleaned out the hoses, blew out the evap in the dash, condenser, chiller. waiting on new driers (cabin ac and chiller) and orifice tube, all to be delivered tomorrow.
i may grab a little more pag oil. no idea how much it needs but i put a couple oz in the compressor but want to add a little to everything when i put it back together

I could give you a load of phag oil for your tubes.

 

[Dantheman1540]

nioce

i ripped about my whole ac system back apart, orifice tube had a little bit of metal on it...maybe a teaspoon worth, wasnt completely blocked. didnt find shavings anywhere else. cleaned out the hoses, blew out the evap in the dash, condenser, chiller. waiting on new driers (cabin ac and chiller) and orifice tube, all to be delivered tomorrow.
i may grab a little more pag oil. no idea how much it needs but i put a couple oz in the compressor but want to add a little to everything when i put it back together

I really contemplated pulling my orifice tube but I’m sick of throwing money at the atmosphere so if it holds out for now it’s staying.

 

[randeez]

I could give you a load of phag oil for your tubes.

lmao

I really contemplated pulling my orifice tube but I’m sick of throwing money at the atmosphere so if it holds out for now it’s staying.

i dont think the metal in mine was the problem, my ac was working just not cooling consistently, pressures seemed high. to get vent temps below like 70* i had to have the compressor output pressure like 240psi+ when usually it would be icing the evaporator over with that much pressure. because of where the gauge ports are on mine - the chiller breaks off before on the high side and after on the low side so i cant really go by them. kind of just use them for reference. not sure what problems ruined driers would cause and they were both only like 10bux each so i grabbed both

 

[Dantheman1540]

lmao

i dont think the metal in mine was the problem, my ac was working just not cooling consistently, pressures seemed high. to get vent temps below like 70* i had to have the compressor output pressure like 240psi+ when usually it would be icing the evaporator over with that much pressure. because of where the gauge ports are on mine - the chiller breaks off before on the high side and after on the low side so i cant really go by them. kind of just use them for reference. not sure what problems ruined driers would cause and they were both only like 10bux each so i grabbed both

$10 for driers is a great price! Pretty sure mine is closer to $60. A clogged orifice tube could cause temps to spike, but if higher temps are what’s needed to cool that’s kinda strange I’d assume it was a compressor issue then.

Ruined driers/moisture in them, usually causes pressures to spike and no cooling to happen. That’s what the google has told me in all of my 12million google searches.

 

[randeez]

$10 for driers is a great price! Pretty sure mine is closer to $60. A clogged orifice tube could cause temps to spike, but if higher temps are what’s needed to cool that’s kinda strange I’d assume it was a compressor issue then.

Ruined driers/moisture in them, usually causes pressures to spike and no cooling to happen. That’s what the google has told me in all of my 12million google searches.

The drier for the cab had like 4oz of oil in it itself after I took it out. So not sure wtf is goin on.

 

[pwtr02ss]

not sure what problems ruined driers would cause and they were both only like 10bux each so i grabbed both

Before I realized what a dryer did, I left one off a camaro I used to have for about a month. Put that ****** back on there and was cruising along then BAM, shit started spraying all of the windshield and engine bay. The crystals in there had soaked up a bunch of moisture and they froze (according to the guy that does ac), pressure spiked and it blew the pop off valve. I replace them every time I have the system open.

 

[Dantheman1540]

The drier for the cab had like 4oz of oil in it itself after I took it out. So not sure wtf is goin on.

Huh that’s odd, if you were close I’d let you have some of my 64oz bottle of pag oil that I’ll never finish.

Before I realized what a dryer did, I left one off a camaro I used to have for about a month. Put that ****** back on there and was cruising along then BAM, shit started spraying all of the windshield and engine bay. The crystals in there had soaked up a bunch of moisture and they froze (according to the guy that does ac), pressure spiked and it blew the pop off valve. I replace them every time I have the system open.

That is terrifying! I’ve replaced it multiple times at this point, but been lucky the last few times that despite leaks the system isn’t 100% totally empty and isn’t exposed to moisture. Down here with our humidity I’d expect even just a half hour of exposure would be too much.

 

[Dantheman1540]

Interestingly enough I have yet to replace that 30amp #2 Stud fuse that supposedly controls the trailer wiring. Yet my trailer lights work fine, so maybe idk what it controls.

 

[pwtr02ss]

Interestingly enough I have yet to replace that 30amp #2 Stud fuse that supposedly controls the trailer wiring. Yet my trailer lights work fine, so maybe idk what it controls.

Thats the fuse for vibrator on the stick shifter....

 

[Fless]

Interestingly enough I have yet to replace that 30amp #2 Stud fuse that supposedly controls the trailer wiring. Yet my trailer lights work fine, so maybe idk what it controls.

That #2 stud is for the trailer brakes. You have separate fuses in the underhood fusebox for the lights.

Stud #1 is for auxiliary power (12v) to the trailer. Neither have anything to do with lights. I hope you're 'enlightened' now...

 

[Dantheman1540]

That #2 stud is for the trailer brakes. You have separate fuses in the underhood fusebox for the lights.

Stud #1 is for auxiliary power (12v) to the trailer. Neither have anything to do with lights. I hope you're 'enlightened' now...

I’m much smarter now! I wonder why that fuse burns out if I don’t have a trailer brake.

 

[Fless]

The four wires for the aftermarket trailer brake controller are all pre-wired and the pigtail/harness is up under the driver's side dash. You could look for the wire bundle around the left side of the steering column behind the knee bolster and see if something's attached or it's shorted. Two of the wires are fairly heavy: the red one is the feed from the fusebox stud and the blue one goes back to the trailer connector (7-blade). Check that red one. I don't recall what colors the other two are, but they're smaller wires.

Both the trailer aux power and the brake controller circuits are live full time - provided the fuses are good and in place!

 

[randeez]

you passed your bad ac luck onto me.

 

[Dantheman1540]

The four wires for the aftermarket trailer brake controller are all pre-wired and the pigtail/harness is up under the driver's side dash. You could look for the wire bundle around the left side of the steering column behind the knee bolster and see if something's attached or it's shorted. Two of the wires are fairly heavy: the red one is the feed from the fusebox stud and the blue one goes back to the trailer connector (7-blade). Check that red one. I don't recall what colors the other two are, but they're smaller wires.

Both the trailer aux power and the brake controller circuits are live full time - provided the fuses are good and in place!

I will have to keep this in mind because I have long considered getting a trailer brake controller and adding brakes to my big trailer, or upgrading to something beefier in the future. The limiting feature for this truck to tow more is 1000% the brakes. Even with the multiple brake upgrades there’s never enough stopping power with trailers.

you passed your bad ac luck onto me.

No pass backs!

What happened now?

 

[randeez]

Mostly my fault.

Also this was rushed because subaru decided to be cunty. Every light on dash, eyesight off, lane assist off, collision avoidance off, no abs, parking brake light on, and ******* power steering went out. I drove it about 40miles to get home yesterday cause **** that pos. Getting towed to shop this morning.

And cadillac is at cadillac for tranny shit. Would have been fine to drive but i assumedy subaru wouldnt shit the bed this week.

So the only reliable vehicle I have is the yukon.

Ordered wrong drier for chiller, looks exactly the same, threads are the same, but the fittings don't go into the shit.
Ran around about 5 auto parts stores they can't look shit up without a vehicle, the part number on the drier is from Australia can't cross reference the shit. It was either leave it out or reuse it...I vacd shit down for an hour and reused it. Still seems kinda ****** up. Ordered like 3 diff ones that should work.

The drier for the cab, Ordered new, worked fine, but it's for an r12 system so I have to put a r134 port adapter on it. Didnt remember to remove the shrader valve before putting the adapter on. Tried to put the adapter back off and the aluminum is so soft that it just ****** the threads up, ruined port, ruined adapter for the low side. After cussing it for a while, I really didn't want to reuse both driers but the cabin one had a second port. So I pulled the Schrader out of it, all I had was a highside (larger) adapter at this point so I put it on, vacuumed down using the highside hose on the low side with the lowside hose off. Was able to get some freon into it. And it all works but it's a ******* mess. Re Ordered everything again to fix it all right.

 

[pwtr02ss]

Mostly my fault.

Also this was rushed because subaru decided to be cunty. Every light on dash, eyesight off, lane assist off, collision avoidance off, no abs, parking brake light on, and ******* power steering went out. I drove it about 40miles to get home yesterday cause **** that pos. Getting towed to shop this morning.

And cadillac is at cadillac for tranny shit. Would have been fine to drive but i assumedy subaru wouldnt shit the bed this week.

So the only reliable vehicle I have is the yukon.

Ordered wrong drier for chiller, looks exactly the same, threads are the same, but the fittings don't go into the shit.
Ran around about 5 auto parts stores they can't look shit up without a vehicle, the part number on the drier is from Australia can't cross reference the shit. It was either leave it out or reuse it...I vacd shit down for an hour and reused it. Still seems kinda ****** up. Ordered like 3 diff ones that should work.

The drier for the cab, Ordered new, worked fine, but it's for an r12 system so I have to put a r134 port adapter on it. Didnt remember to remove the shrader valve before putting the adapter on. Tried to put the adapter back off and the aluminum is so soft that it just ****** the threads up, ruined port, ruined adapter for the low side. After cussing it for a while, I really didn't want to reuse both driers but the cabin one had a second port. So I pulled the Schrader out of it, all I had was a highside (larger) adapter at this point so I put it on, vacuumed down using the highside hose on the low side with the lowside hose off. Was able to get some freon into it. And it all works but it's a ******* mess. Re Ordered everything again to fix it all right.

The camera went out on Stephs car (Honda accord) that controls the forward collision and lane keep, it made a bunch of lights come on like that.

 

[randeez]

The camera went out on Stephs car (Honda accord) that controls the forward collision and lane keep, it made a bunch of lights come on like that.

towed to my buddys shop, only code that comes up is a speed sensor, so hes going to start there
yukon kicked ass today, 200+miles for sites today, AC was enough to keep comfortable but could still use some work - prob not going to touch it till new driers come