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.