I have Acura RDX 2007 and the AC does not work. I took it to dealership/mechanics and they saw that the outside air temp sensor somehow banged condenser and had to replace the condenser. The diagnostic tool says B1227, I checked the outside air temperature sensor with a multimeter and it looks good. Could it be the connector? how to test them.

I tried self-diagnostics (holding "Off" key and clicking defogger key 5 times) but it does not show any error (it was supposed to show "C and Auto" for the same DTC shown in Diagnostic tool. )

Everything else was checked out by dealership mechanic and now it has become too expensive for the worth of the car. I am thinking it could be wiring or connectors, can anyone help with how does the signal flow and to where? like does outside temp air sensor signals the climate control unit first or can it be bypassed?

Command from HDS engages the AC clutch and it works, so the circuitry looks good (still not sure about the harness that goes from outside temp sensor to climate control unit)

  • Welcome to Motor Vehicle Maintenance & Repair! My son experienced the same kind of issue with his BMW. The outside temp sensor was reading -40°F (by the dash indicator) even after putting in a new sensor. He found when it isn't reading correctly or not at all, affects how the A/C runs. He was able to replug the sensor in and now the A/C is working flawlessly. My suggestion is, since yours is showing an "open" fault, the computer isn't reading the outside air temp sensor. You need to trace the wiring and find where the wire is broken or not connected. Jul 27, 2021 at 20:59
  • Thanks for the reply, I was about to do it, the thing is - i live in an apartment and we are not allowed to do any type of mechanic work on cars on the parking lot, this leaves me one choice - to go to a friends place and I can probably only do it once, so wanted to make sure I get all of the checklists of things to look for before giving that a try and possibly fix it in one go. just glancing over from outside - wiring looks good but have to open it up to make sure Jul 27, 2021 at 21:59
  • Well, get the wiring diagram for your car and make sure you know what goes where.
    – Solar Mike
    Jul 28, 2021 at 6:24

1 Answer 1


With virtually every vehicle in the USA since 1996 requiring emissions controls with on-board monitoring (OBDI or OBDII) while the engine runs. manufacturers incorporated many programs to monitor almost everything else with electronics; abs/tc/esc, airbags, electronically controlled xmission, hvac and engine. Error codes are generated for anyone having generic or better reader/scantools to decode these errors. B1227, if I'm not mistaken, is an error code that won't be read by generic readers.

Here's one site describing B1227 for your '07 Acura RDX; https://www.dtcdecode.com/Acura/B1227

  • I understand what the DTC number means, just that I wanted to understand the flow of the signal and the circuit before even I open up everything apart, it would be nice to have some visuals of the wiring harness with regards to the sensor and climate control unit. I am that person who does more research first so that I have to do less trial and error method mainly due to other constraints. Jul 28, 2021 at 4:06
  • Unless you can seach for free service manual info online, access to alldata from your local library, alternatives are buying used factory manuals, subscribing to all data.diy or Mitchell for online access to service manuals equal to factory manuals for accurate info. This includes error codes, diagnostics and troubleshooting as if a dealer mechanic or technician.
    – F Dryer
    Jul 29, 2021 at 4:33

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