DLB AC_High_Side_Pressure 6525.8 psi
05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #1
Tongue DLB AC_High_Side_Pressure 6525.8 psi
***SOLVED***

•Circuit for air conditioning
•Open circule roe re censor wiring
high side pressure sensor
on any wire, failed sensor, or
short to ground on the signal wire
•AC_High _Side_Pressure
•6525.8 PSI. No fault code is
generated by this condition

So i have no ac atm..i have been stupid and thrown parts at the system because i didn't have an understanding how read DLB info.. After research and digging through the wiring diagram to the best of my ability, it seems the issue is related to the high pressure switch being inaccurate. I have replaced both the high and low, i have replaced the hvac controller, sleeper blend door actuator, checked the charge. I have no power going to compressor. It will operate forcefully in DLB. I noticed the high pressure read -54°F and 6525.8 psi... clearly this seems to be the issue. Like i said, i replaced this high pressure sensor.

As far as i can tell, the 3 wires route to a big connector on the firewall. Wires appear to be decent in between. My question is had anybody had this issue before and after looking up the wiring diagram, there is a zero volt reference mentioned a couple times. WHERE IS THIS? And am i going in right direction? The 3 wires seem to be signal only wires and are 2 grey 1 lite green. I replaced body control module a couple years ago do to a derate in def issue and don't want to replace it again because of this other issue.

Sorry if this is scattered brained. I'm tired of no AC and love in Florida.
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05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #2
RE: DLB AC_High_Side_Pressure 6525.8 psi
What are the symptoms when not trying to fool it?.

After cranking the truck and turning on the A/C to max ...

Does it allow the A/C compressor to kick in for up to about 10 minutes or so after engine is cranked up?, and then dies?.

Does it not kick the compressor on at all?.

Is it commanding the engine fan to run all the time?.

Instead of throwing sensors at it randomly.. Has anyone bothered to purchase a brand new OEM thermistor from a certified stealers$it and measure its resistance across its 2 pins .. and then simply measure the ones installed at either side of the expansion valve to see if they read the roughly same thing at room temperature?.

Has anyone bothered to see what the ambient temp is reading in the engine ECM?.. because this indirectly effects the cab controller A/C system and how it operates, or if it wants to fail the system. Making sure it is not reading too far away from the actual temps outside?.

-== when did this issue start?...

Before replacing the cab module?.

after replacing the cab control module?

.. or was it working normally at one point and stopped?.



and what do you mean by ...
(05-24-2023 )Satch Wrote:  ... I replaced body control module a couple years ago do to a derate in def issue and don't want to replace it again because of this other issue.
...

That statement does not make much sense.- Derates or other problems due to the emissions systems on the engine are not related to the cab module. the cab module also does not have to be replaced, or re-programmed, if someone de-mandated (made a delete) to the engine... so your statement makes no sense to me.

also.. here is an older post that talks about about the A/C systems on navistar trucks...
http://rawze.com/forums/showthread.php?t...4#pid40694


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: Satch
05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #3
RE: DLB AC_High_Side_Pressure 6525.8 psi
This is one of MANY Dumb things Navistar has done.
AC_High_Side_Pressure
Location and pin 1600-B12

Open circuit for air conditioning
high side pressure sensor wiring
on any wire, failed sensor, or
short to ground on the signal wire
6525.8 PSI. No fault code is
generated by this condition

This is from a Navistar tech letter IK1900207. To see this part it has to be REV 10. This is on the last page or two. I found some copies online but can't find a high enough revision level. I can post a copy with Rawzes permission.

NAV apparently never set up a normal code for problems related to the high pressure circuit so this was the work around but it was YEARS before they bothered to tell anybody. And you only see it if you have DLB and are looking at that page.

I think I posted about this before but can't find it.
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05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #4
RE: DLB AC_High_Side_Pressure 6525.8 psi
(05-24-2023 )Rawze Wrote:  What are the symptoms when not trying to fool it?.

After cranking the truck and turning on the A/C to max ...

Does it allow the A/C compressor to kick in for up to about 10 minutes or so after engine is cranked up?, and then dies?.

Does it not kick the compressor on at all?.

Is it commanding the engine fan to run all the time?.

Instead of throwing sensors at it randomly.. Has anyone bothered to purchase a brand new OEM thermistor from a certified stealers$it and measure its resistance across its 2 pins .. and then simply measure the ones installed at either side of the expansion valve to see if they read the roughly same thing at room temperature?.

Has anyone bothered to see what the ambient temp is reading in the engine ECM?.. because this indirectly effects the cab controller A/C system and how it operates, or if it wants to fail the system. Making sure it is not reading too far away from the actual temps outside?.

-== when did this issue start?...

Before replacing the cab module?.

after replacing the cab control module?

.. or was it working normally at one point and stopped?.



and what do you mean by ...
(05-24-2023 )Satch Wrote:  ... I replaced body control module a couple years ago do to a derate in def issue and don't want to replace it again because of this other issue.
...

That statement does not make much sense.- Derates or other problems due to the emissions systems on the engine are not related to the cab module. the cab module also does not have to be replaced, or re-programmed, if someone de-mandated (made a delete) to the engine... so your statement makes no sense to me.

also.. here is an older post that talks about about the A/C systems on navistar trucks...
http://rawze.com/forums/showthread.php?t...4#pid40694
6

Truck is a 2015 model year. Correct me if I'm wrong, but i do not believe it has the thermistors like older prostars. Well not the ones easily accessible and known to fail ones that's popular.

The ac doesn't work at all. No power to ac compressor at all.
This started in January of this year. I was running up north a bit and didn't use ac much. I cannot say exactly when this problem started other than in January. The ac has worked fine for several years. Other than the clutch going out 4 years ago. The body control module was replaced like 2 or 3 years ago. And yes i agrees it doesn't make sense, but the international near Nashville is who did this... my codes showed def heater stuff, they said can controller and the truck worked fine after. Yes im sure i got raped. But i digress.

The dash says the ambient is very close to what Google says the temperature is.

This truck has NOT been demandated. It's still stock to my knowledge. Uses def.
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05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #5
RE: DLB AC_High_Side_Pressure 6525.8 psi
(05-24-2023 )DVT873 Wrote:  This is one of MANY Dumb things Navistar has done.
AC_High_Side_Pressure
Location and pin 1600-B12

Open circuit for air conditioning
high side pressure sensor wiring
on any wire, failed sensor, or
short to ground on the signal wire
6525.8 PSI. No fault code is
generated by this condition

This is from a Navistar tech letter IK1900207. To see this part it has to be REV 10. This is on the last page or two. I found some copies online but can't find a high enough revision level. I can post a copy with Rawzes permission.

NAV apparently never set up a normal code for problems related to the high pressure circuit so this was the work around but it was YEARS before they bothered to tell anybody. And you only see it if you have DLB and are looking at that page.

I think I posted about this before but can't find it.

IK1900207 shows me a pdf when Googled MC-10115482-9999.pdf

I doesnt seem to allow me to download that DLB session. I'll see what else I'd anything i can do that may help. The sessions is what i want aware of until recently.
replyreply
05-24-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #6
RE: DLB AC_High_Side_Pressure 6525.8 psi
If it is this, https://static.nhtsa.gov/odi/tsbs/2015/M...2-9999.pdf it only goes to page 7. Info is on page 10 on my copy. There are variations in the wiring. Post your VIN and I can look. Having been burned badly over the years by not being in the correct manual. I work from the build date and build codes if at all possible.
There are two thermistor versions of this system and then the latest was no thermistors. Do you have an orifice tube or thermostatic expansion valve system? With DLB I can do a get from history on your VIN and get your exact file/config. Might take me a few days, I have several wiring problems at the moment.

Connect your grey wires, (are they k99AA and K6DB?) at the transducer to a DC voltmeter. You should read 5 volts plus or minus a few tenths. If to don't get a reading at all something is wrong. The green wire is the signal going back the Body Controller (BC) . At this point DLB has told you about all you need. Until you get a correct pressure reading and correct temperatures for the thermistors the system isn't going to work.
ZVR is essentially a ground provided by the BC. It is also part of the thermistor circuit.
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 Thanks given by: Rawze , Satch
05-25-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #7
RE: DLB AC_High_Side_Pressure 6525.8 psi
I believe it's a expansion valve system. I'll check again when it stops raining
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05-30-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #8
RE: DLB AC_High_Side_Pressure 6525.8 psi
***Solved ***
If you don't have a power probe with a wire trace, go get one. Ect3000... found my broken wire in 10 minutes...

I had one broke grey wire from high pressure switch completely broken. The other two had exposed wires also. About 24" from the ac high pressure switch.

Thank you Rawze for this forum and knowledge base.
Thanks DVT873
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 Thanks given by: Nostalgic
05-30-2023, (Subject: DLB AC_High_Side_Pressure 6525.8 psi ) 
Post: #9
RE: DLB AC_High_Side_Pressure 6525.8 psi
(05-30-2023 )Satch Wrote:  ***Solved ***
If you don't have a power probe with a wire trace, go get one. Ect3000... found my broken wire in 10 minutes...

I had one broke grey wire from high pressure switch completely broken. The other two had exposed wires also. About 24" from the ac high pressure switch.

Thank you Rawze for this forum and knowledge base.
Thanks DVT873

Y’all can also jump on eBay and order a tone generator. They are 25-50$ depending on brand. They were used by telephone companies to find faulty wires and work great.
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 Thanks given by: Nostalgic




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