Can you download a Thermo King or Carrier unit on your phone?
Ask Google and you'll get a flat no. That answer is correct — and it's answering the wrong question.
WinTrac and TRU-Tech are Windows programs. They need a laptop, an install, and a cable. You cannot run either one on a phone, and no amount of wishing changes that. Every forum, every search result, every service manager will tell you the same thing, and they're all right.
But here's what that answer quietly assumes: that the software is the download.
It isn't. The unit writes the download file itself. Put a USB stick in a Thermo King and run a ServiceWatch download and the controller writes a .wtd file to that stick with no PC involved at all. That file is a record of your unit, on your customer's trailer, containing your fleet's data. WinTrac is simply one program that knows how to read it.
So: can you get unit data on your phone? Yes. Not by running WinTrac on it — that's impossible. By reading the file the unit already wrote.
What actually works, honestly
| Method | Phone? | Notes |
|---|---|---|
USB stick → .wtd file | Yes — any phone, iPhone included | Unit writes it. Open it in your browser. |
| WinTrac CSV export | Yes | If someone already pulled it with a laptop. |
Carrier .dcx from TRU-Tech | Yes | Same idea — read the file, not the app. |
| Cable straight off the unit — Thermo King and Carrier | Yes on Android Chrome. Desktop Chrome/Edge too. Not iPhone/iPad. | No WinTrac, no TRU-Tech. In beta — see below. |
| WinTrac or TRU-Tech itself | No. Never. | Windows applications. Correct answer to the wrong question. |
The USB stick route, start to finish
- Put a USB stick in the unit and run a ServiceWatch download from the controller.
- Pull the stick. You now have a
.wtdfile — no laptop, no WinTrac, no licence. - Open Reefer Tech Pro on your phone, tap Choose log file, pick the
.wtd. - You get temperatures, setpoints, defrost events, both zones on a multi-temp, alarms, and a plain-English AI summary of what went wrong.
That works on an iPhone in a yard with one bar of signal. It works on Android. It works on a laptop. It's just a file and a browser.
No USB stick? Pull it straight off the unit with a cable
You don't have to wait for the unit to write a file. Plug a USB–serial cable into the unit and the app talks to the controller directly — Thermo King over DataPac, Carrier over Zenith — and pulls the download itself. In a browser. With no WinTrac and no TRU-Tech installed anywhere.
This is the part people tell you is impossible, and it's the part we're proudest of. Both protocols were recovered from real captures and rebuilt from scratch, right down to the CRC.
It's in beta and we say so in the app. The protocols are right, but baud rates and download paging still vary between controllers, and we're tuning it against real units in the field. If it doesn't reply first time, try Auto-detect baud. When it works, it's the fastest route there is; when it doesn't, the USB stick always works.
Why the cable download won't work on your iPhone
Pulling a download over a USB–serial cable needs a browser feature called Web Serial. Apple has never implemented it and has formally objected to the standard on privacy grounds. And because Apple requires every browser on iOS and iPadOS to use its own engine underneath, installing Chrome on your iPhone doesn't help — that Chrome is Safari wearing a different icon.
So cable downloads need desktop Chrome or Edge, or Android Chrome. On an iPhone or iPad, use the USB stick. We'd rather tell you that up front than have you stand at a trailer wondering why the button does nothing.
"But my boss says it can't be done"
He's right about WinTrac. He's assuming the file and the software are the same thing, which is a fair assumption if you've spent twenty years with a laptop bag over your shoulder.
We decoded the download format and wrote our own reader for it, then checked it against WinTrac's own output until every reading matched — not close, identical. On the last single-temp unit we validated, all 1,047 readings matched byte for byte. On a multi-temp, 4,542 of 4,542 on Zone 1 and 4,162 of 4,162 on Zone 2. If our numbers ever disagreed with WinTrac's, we'd have a bug, and we'd want to know.
Being straight about the limits: alarms aren't decoded yet on the newer single-temp controllers — the app tells you that rather than showing a blank. On long logs, times of day are exact but older dates can drift. We label all of it in the app. Guidance is advisory: always verify against the manufacturer's official procedures before servicing.
Try it on the next unit you touch
Free to sign up, works in any browser, nothing to install.
Running a fleet and want your whole team on it? Email us and we'll quote it.