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HVAC system inoperative after mechanic tries to fix air conditioning


Topic starter

I have a 2012 Toyota Camry LE, under 29,000 miles, automatic. Last summer my ac would not blow cold air. Adding refrigerant did not help. My mechanic told me it was probably a bad AC Compressor. Looking online I tried to replace AC Compressor Flow Sensor with a Dorman 926-818 but all I did was break my original AC Compressor Flow Sensor with parts of it still attached to the ac compressor. I figured this wasn't a huge issue since I figured I'd just need to replace the AC Compressor anyway.

I brought the car to my mechanic thinking he'd replace the bad AC Compressor, although I didn't tell him about the AC Compressor Flow Sensor I had broken since added the refrigerant and told me I'd need a new compressor. He then calls me and tells me he can't fix it and "worked on the car all day" but couldn't figure out what was wrong.

I get done with him and then realize now not only is my AC not blowing cold but I now don't have any ability to have air flow in my car. No heat, no ac, no fresh air flow, no ability to use the defroster, and the outside ambient temperature senor is reading E. He tried pretending I brought the car in like this but upon protesting he checked all the fuses and all of them seemed fine. Do you know what the problem might be? Also the lights to the temperature panel do come on normally when I turn the lights on so I'm pretty sure the panel itself is getting power.

Thank you.

5 Answers

Take it to a qualified automotive ac specialist and get your money back from the first guy.


It sounds like the module controlling the HVAC system, or the wiring to it, has been borked. You say fuses are OK so it's not going to be that simple. A professional-grade scan tool is needed to do bidirectional testing on the system.


I would scan it for codes to see what's the car unhappy about - I'd expect no communication or for the module to not show up...

But I agree with Chuck that it's probably wiring or control module related...

And with Doc that you should get you money back from that clown and go to a professional that knows what he's doing.

I wanted to thank everyone who took time to reply to me. He had brought up (by watching a YouTube video, no scan tool) that the problem could be the AC Control Module, looking on the internet it seems this same part is also called the AC Amplifier sometimes.

The reason I turned to the internet for help is I called 7 mechanics in my area, everything from a typical gas station mechanic, to the dealer, to a non dealer where people who have money to spend can go, ect... and whenever I mentioned them using a scan tool all of them told me they don't really use scan tools to diagnose HVAC problems, which left me dumbfounded as my own playing a mechanic on the internet showed me mechanics with good scan tools even being able to read what temperature the air is blowing at.

All of them were going on about removing refrigerant, checking for leaks, and not really using a scan tool. I don't know why they'd need to remove refrigerant and check for leaks in order for me to have the air flowing at the outside temperature and my defroster working again. Hopefully I can get this problem resolved soon and I will post a reply once that happens. Thank you all once again.

That’s the thing - with A/C issues you don’t scan for codes, with electronics issues (like no com with HVAC module) - yo do!


That’s because the car doesn’t know why the AC won’t cool, but it can give you context as to why there’s no fresh air and why it can’t display the outside temp.


I know an AC repair techs’ first reaction to any issue is trying to replace the refrigerant - but with issues like what you described thats rarely the solution.

What you described with E instead of temperature and no fresh air - probably has little to do with the mechanical aspect of the HVAC system (it can be, but I’d assume it’s not)


BTW, AC guys who know what they’re doing know electronics and use advanced diagnostics scan tools - cause a lot of AC issues on modern cars (especially euro cars) are not mechanical but electronics related.


If you want that fixed the dealer won't charge you until it's done, that's what I say to what can seem impossible

Topic starter
I finally was able to fix this problem and am replying to my own post so that if anyone else has this problem, they can try what I did.

It was the ac control module that had been shorted out. The part number for my 2012 Toyota Camry LE was 88650-06491. Since the cheapest dealer price was $438.28, I bought the part used off a wrecker from Ebay.

As soon as I replaced the part and plugged it in I once again had working heat, fresh air flow, my defroster worked again, and the outside ambient temperature sensor read as it should. I used this video to show me how to remove everything to access the ac control module.

In case links aren't allowed it's called "2013 Toyota Camry HVAC control Module location and removal" by Crowtown Auto. As the video mentions, unhook the battery, at least the negative terminal before removing and replacing the ac control module so you don't end up shorting your replacement part.



Afterward I went to a more reputable mechanic to replace my ac compressor and now I also have ac once again.
I wanted to thank everyone once again for answering my questions and I have to add I'm not surprised even in the slightest that it was the Scotty Kilmer Forum that answered my question correctly and the most quickly. Scotty is the best mechanic for anyone who wants to do it themselves without pretending everyone is going to spend hours a week and tens of thousands of dollars in equipment to maintain their car.