+- Rawze.com: Rawze's ISX Technical Discussion and more (http://rawze.com/forums)
+-- Forum: Big Truck Technical Discussion... (/forumdisplay.php?fid=1)
+--- Forum: International Trucks Related Help (/forumdisplay.php?fid=69)
+--- Thread: 2018 lt625 a/c troubleshooting checklist (/showthread.php?tid=10642)
2018 lt625 a/c troubleshooting checklist - Kw9006nz - 06-22-2026
Afternoon guys,
In Utah and it's hot.....a/c was freezing all morning, stop for a quick bite to eat (beaver taco, in beaver Utah get the shrimp burrito) came out and the check ac warning on the display flashed then disappeared. No codes no thing just warm air.
First thing I grabbed my gauges to see if I need a splash, the low and high side are reading 120 psi.
(Left my ohm meter at the house will be there tomorrow) what should be the next step?
Do I just replace the pressure sensors straight away as they're 8 yrs old
Then replace the thermistor? also assuming it's also 8 yrs old
Finally how to reset the bcm? I tried removing the fuse for 5 minutes while also shutting the truck lol thanks google ai
What else to check?
Last ih a/c I worked on was a good ol 97 9400 many more things I'm not familiar with
Thanks in advance
RE: 2018 lt625 a/c troubleshooting checklist - Kw9006nz - 06-22-2026
Next question does a 2018 lt625 even have a thermistor?
International stealership says it doesn't so I asked what it did have and his reply and I quote
"Idk but it doesn't list a thermistor"
Right.....thanks
RE: 2018 lt625 a/c troubleshooting checklist - Rawze - 06-23-2026
maybe this related info helps...
https://rawze.com/forums/showthread.php?tid=6106&pid=53176#pid53176
RE: 2018 lt625 a/c troubleshooting checklist - Kw9006nz - 06-26-2026
Thank you rawze for the info
To wrap this thread up I did get a 2609 fm 15 code on my scan gauge witch is a/c pressure low warning
Finally got a chance to work on it this morning, unhooked batteries for 30 min while puttering around changing the high and low pressure switches, hahaha ghey werent bad i found out. hooked everything back up check ac warning quit flashing and it ran the compressor along with a horrendous rattle and tick it would produce 55 psi on high side and 26 on low side
The compressor is failing, didnt find any shavings or chunks so on with a new compressor and back to cold days while it's 100 deg outside not counting humidity
Have a great 4th boys!!!
RE: 2018 lt625 a/c troubleshooting checklist - DVT873 - 06-27-2026
Post the last 8 of your VIN, and I can get you a copy of the 4000-plus-page technician manual for your truck and the circuit diagram manual. The manual will show you more than you may want to know! The new circuit diagrams are a struggle, at least for me. They are now "interactive." I have not had to use them more than 3 or 4 times. They are engineering-based and have a LOT of information, but for me are a bear to navigate. Rawze will probably navigate them with no problem!
A note on A/C. Think about replacing the belt and tensioner. Use OEM if possible. Over time, both wear and the belt starts to slip. Slippage builds heat in the clutch, changing the coil resistance, which changes the amperage going to the coil. The body computer watches this like a jealous bride, and if it goes out of a pretty narrow range, power to the clutch is shut off. This gives a code of something like "clutch current above/below spec" which can baffle the shi#t out of you if you've not run into it before.
FWIW, almost all OEM's have been using some variation of this for a long time.
RE: 2018 lt625 a/c troubleshooting checklist - Yauchout - 06-28-2026
(06-23-2026 )Rawze Wrote: maybe this related info helps...
https://rawze.com/forums/showthread.php?tid=6106&pid=53176#pid53176
I thought i would just add even though his problem is fixed the 2016 and up wont have that style of thermistors they did away with them they have a frost sensor directly on the evaporator for frost control instead. they can fail and cause the compressor to stop until replaced. it can also cause continual freezups of the evaporator. I am sure they can be checked in diamond logic if you have access
RE: 2018 lt625 a/c troubleshooting checklist - Kw9006nz - 06-29-2026
JN501654. And thank you for the tid bit about the thermistors lol I stared at the truck for a solid ten minutes while drinking a beer and saying I swear if I have to tear your whole dash out for anything to get me cool air I will but I ain't gonna like it, hahaha
Also as preventative maintenance any truck I aquire I change belts tensioners and idlers and throw the used ones under the bunk for just in case, and then regularly at year intervals, I've found long ago no matter how many belts you put on a bad idler will destroy it in short order, lesson learned not doing that again
RE: 2018 lt625 a/c troubleshooting checklist - DVT873 - 07-01-2026
Here you go, download the info ASAP because this link dies in 72 hours from posting. Posted at
2026070117:40
Rawze you might find the schematic format interesting. This is the only format for the newer trucks. Because I don't use it often, it is a struggle, and I usually need to look in the user guide. Sometimes it is very useful because it shows the harness location on the truck.
{post removed by Rawze, software file trading is not allowed on the forum unless it is from the equipment makers wwwsite directly. People can PM this user if they want the link instead}.
RE: 2018 lt625 a/c troubleshooting checklist - DVT873 - 07-02-2026
Rawze, it was manuals, not software, but I understand, FWIW, the wiring is on the International Public Body Builder website. Scroll down a little and it's there. The SI is different but shareable if I don't charge for it. Still, it could be a hassle, and I understand you wanting no part of that.
Wiring here https://www.international.com/products/resources/tem-body-builder/body-resources