2009 Honda Civic A/C won’t work after replacing compressor

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Edited by: Francisco Diez Video & Photography

[@MarketingCoachKen]

2009 Civic is a fan favorite. Good to see an a/c repair on one of the most popular cars on the road.

[@israelperez-sg8er]

Congratulations, great job! You´re a very patient man in your work, viewing from Guatemala, C.A.

[@chuckvoss9344]

Good job. Your using the scan tool to step through the process saved you a lot of time.

[@OzMechanics]

Thanks for stopping by and watching. Hope all is well

[@JesseAutoDiag]

If I was yor typical mechanic at the Dealership, I would replace the AC Compressor, PCM/ECM, BCM & AC Amplifier/ Module, Head Unit, and Engine Harness, and if that dont fix it, I may throw in a Transmission + TCM or even a fuel pump at no charge and depending if any leaks maybe even a power steering pump and hoses, and on a good day an alternator. but It'll have cold air on the way out for $6,500 + tax.... Thanx for the great Diag Videos Mr Oz... :)

[@DuaneDonaldson]

AC Systems are a major problem for many Techs to understand the actual LOGIC within the HVAC Head Control Unit mixed in with the PCM and possible BCM for many vehicles. Not all scan tools will show 100% of all sensors involved and we also do not know all the sensors involved, hence the problem many of us have of not fully understanding the entire system, especially when the scanner is not informing us of EVERYTHING we need to see. Most of us do not care to read up on the Service Info to be better educated on the system and different makers use different LOGIC increasing the difficulty of becoming HVAC professionals. Some scanners do not show the EVAP Temp Sensor PID, if it is not working properly the LOGIC in the Head Unit will not allow the PCM to turn on the Compressor, not because the PCM blocks the signal, but because the Head Unit does not send a signal to the PCM. Many Techs can see that this output from the Head Unit is missing, but they don't know why, so they swap in a new/used Head Unit when the actual problem is a sensor that the Scanner does not have a PID for. There may be an Ambient Temp Sensor in an outside mirror assy that is bad, how many Techs know to look for this, it's all about proper training on all makes which can take years to learn on such a seemingly simple system. On some late-model cars, the HVAC is now affecting other systems that are totally unrelated, & shutting them down, it's getting crazy. The Engineers are forcing people back to the Dealer to get repairs because the HVAC is shutting down the ABS and TRAC, etc. Why hook up gauges this early, the pressure switch or transducer will give you the proper PID data, either the switch is on or pressure is within limits, and deeper diag comes later if you don't trust the scanner readings. HIGH & LOW AC pressures are about equal so the system has evened out static, pressures are trustworthy at this point. There you go, AC pressure transducer 500PSI, way too high to allow the system to turn on based on proper LOGIC in the Head Unit. AC Pressure Sensor almost 5V, also too high. We need to spend more time creating our own Custom PID Data Listings per vehicle so we know what a normal hot day AC Pressure Sensor Static reading ought to be but in this case, the 500PSI is a dead giveaway. After watching 10s of thousands of KZbin videos Bro, the code readings need to be around the 1-minute mark on average of your video, here you are 8 minutes in, some systems will not allow the system to operate based on codes being present, not saying this is the case but, #1 verify customers complaint/symptoms, #2 scan for codes. We all have our own set of rules to follow, the real-world problem is when we throw out our own rules and don't follow our own tried and true proven set of rules step by step. Also in the real world, if we charge for the first hour of diag, at least this job can be diagnosed in one hour. Thank you for verifying the 2.5V (correct V ??) is a BIAS, using a test light as a load is another test to pull down the BIAS. I wish that you would have retested the 2.5V BIAS with a good Head Unit. I wish you would have tested the missing voltage not going into the connector of the Head Unit and maybe jumped it in at that location. This follows what I mentioned missing LOGIC not allowing the system on signal being sent to the PCM. Thank you for showing that the AC Pressure Transducer Voltage is Proportional to the system pressure output, as pressure increases, the voltage increases. We love to see all tests showing a bad system are then retested to show a good system so we know what to look for mainly for the younger troops. WHO is paying you, the owner who should be getting warranty work, or the shop is paying you to cover the warranty? Not a real problem but I notice that not many techs frequently recheck for new codes once in a while during maintenance. Sometimes this matters. I love your channel Bro, wish you could post many more videos, you are located a ways down my listing mainly based on the number of videos per year but your overall rating of usefulness to an experienced tech is 65% which is good but quantity out-weighs usefulness in my library. I dont care for DIY type stuff and tool reviews, need to have some of the 4 S's, scanner scope schematics and service info. Thank you for all that you do. To give you some data, I just dropped Rainman Ray to your level as he was #1 but he does a lot of regular maintenance and no deep diag. I also have you one level above Super Mario and SD because they don't upload much anymore, too sad. You did not average 2 videos per month in 2023, can you increase it to 1 per week, it would really help your ratings to all viewers, I am sure, cheers.

[@randyf929RR]

Actual constructive criticism. 🙏 Completion on both ends; This is what makes the world go round! 🙏

[@billrimmer5596]

Very nice diag!!! The debris was evidence that the compressor failed and that in turn plugged the condenser. I recently did an Accord of the same year. The desiccant bag on the side of the condenser failed and plugged at least half the condenser with a million little balls. Before replacing the condenser my high side gauge wasn’t reading high at all. Remember, the pressure switch/transducer is downstream of the condenser. Also, the high side pressure access port is also downstream of the condenser. BEFORE I replaced the condenser and flushed the rest of the system the high side gauge read low pressure and the pressure relief blow off valve was venting the high pressure. That was scary!! POW, pow. New condenser and flush fixed the system. Works fine now. That pressure relief valve is super important. Years ago a Chrysler blew the compressor to smitherines while I was sitting in the driver seat after charging it. It had a bad expansion valve. The explosion scared my wife who was in the house about 100 feet from my shop. Refrigerant oil was everywhere!! What a scary mess that was.

[@artiemejia3695]

Great work! I’m having a similar issue with a 2010 civic.

[@orinmangar2333]

Could it have been a faulty head unit in the beginning? If so, changing out the ac compressor and other parts were expensive and possibly unnecessary. It is important to get you to diagnose b4 replacing parts. Great job Oz.

[@faroukkhan6777]

Thanks Oz keep up with all your great work,, 👌

[@edwardthayer9386]

I HIGHLY doubt they flushed it!🤦‍♂️ OZ you are a great technician and you are really good at these videos! Your attitude is everything!👑 people think I'm weird when I get so excited about fixing things! I laugh also when you get hype!

[@bartscave]

Thanks for sharing! Excellent diagnosis and video.

[@OzMechanics]

Thanks for stopping by and watching

[@JimmyMakingitwork]

It can confuse many mechanics when the sensor and pressure port are far away from each other. ;) Always check codes guys on any modern car before hooking up the AC machine. Nice work!

[@nightwolf29]

Good job on the diagnostic! Great video as always!

[@OzMechanics]

Thanks for stopping by nightwolf

[@mmichaeldonavon]

Very nice diag. Had several problems - you found them. Good job.

[@OzMechanics]

Thanks. This one was for sure a fun one to fix and film

[@advancedleveldiagnostics]

Great job, thanks for sharing! The only thing I would have done differently, which you probably did off camera is check the ground for the controls.

[@OzMechanics]

Yea, that shot was actually recorded but with no audio that’s why I put that transition point with the black screen. And just put customer agreed

[@user-dl2ef8bw9f]

Oz mechanic good job, thank you

[@borgsimpson935]

Diag great info. Excellent tutorial

[@OzMechanics]

Thanks borg. This was a fun one to film

[@GkbjlgGkbgljg-my8jc]

Thanks for you vidéo 😉👍

[@AdrianGonzalez-eh9im]

Goodjob amigo

[@mikechiodetti4482]

I think you diagnosed it correctly. Ya the clutch would engage with your diagnosis tool, but the false reading of over 400 psi was one problem. Then comes the test. Surprise! Bad dash switch. No one knew that switch was bad, so you diagnosed that part properly! Overall....GOOD JOB! On to the next one.

[@luismarty1685]

Fantastic bro.

[@edwinmartinez1756]

excellent diag skills my bro!

[@OzMechanics]

Thanks for watching Edwin

[@fredsalter1915]

So close to 100k!!! PS- Ivan would have opened the HVAC head unit ;-) Rock on, Oz!!!!

[@OzMechanics]

Actually got to hang out with Ivan 2 weeks ago. Pretty cool guy

[@fredsalter1915]

@@OzMechanics You got to meet the rock star?!? You lucky!!! God bless, Oz!!

[@scientist100]

Unfortunately with these; they are microchips and not mechanical switches that provides continuity. They are ground driven as he shows. The module recognizes the button push and toggles on or off as it is pressed. Holding it down does nothing but change the status on or off.

[@shaunblakemore7150]

Great job 👍

[@OzMechanics]

Thanks for watching Shaun

[@russellhltn1396]

Interesting. Given the scanner status for the "A/C switch" changed when you grounded it, it suggests it's not really a computer input, but rather a voltage measurement at that point.

[@themechanic6117]

Nice work

[@OzMechanics]

Thanks. This one was a fun one

[@oldbiker9739]

nice work .

[@OzMechanics]

Thank you for stopping by

[@scientist100]

You should have tested the input integrity of the switch head unit. There are two inputs and outputs for this. One to illuminate the button itself and the other to the hvac module. These cars are complex and im glad it wasnt a wiring issue. One thing i also learned, some cars are crazy where you dont know what else the modules are monitoring prior enabling the switch to request ac compressor on; not easy if tech info is not available.

[@jar6588]

Well this vid made me subscribe ,great job bro✌️🍺🇺🇸

[@OzMechanics]

New one coming out in a bit

[@jar6588]

@@OzMechanics 👍 Orale

[@mike-yp1uk]

Good fix

[@ebrahimsadeghi5883]

Awesome 👏 ❤

[@joserivera6523]

That's why is good to do a dionostic always good one oz

[@jordysandino6577]

Bonito vídeo como siempre primo . Una pregunta ¿ donde compra los conectores de pruebas ? Muchísimas gracias primo

[@OzMechanics]

Tengo los connectors en mi tienda de Amazon. Lo tengo en el comentario número uno.

[@jordysandino6577]

Muchísimas gracias primo

[@aaronkoivu]

93psi when ac compressor is off, that the same ambient temperature 93F….is this a quick check that the sensor wiring is good? Good ground? Good computer? Chrysler technology teacher show this test to the class when this transducer 3wire system was installed on the LH(300M) plate form back in 1998

[@aymenmohamed1134]

Awesome

[@martinarrieta248]

Grasias

[@OzMechanics]

Gracias a ti. Por pasar

[@davidgriffin14]

You and Eric need to do another video together.

[@OzMechanics]

We need to get in Eric’s KZbin page and push this

[@aaronkoivu]

4.98volts is that open circuit or 5.0 volts

[@edwardthayer9386]

NO NO NO NO!!!! Your skills are why you are there!!!!

[@swav100]

What kind of suitcase is that

[@Tacosauce22]

I think the shop loaded up the parts canon without a real diagnosis. The old compressor was probably good and nothing wrong with it. Good fix dude.

[@OzMechanics]

The metal residual shows that compressor damage did happen but I’m not sure if this was from an old issue

[@rrmech11]

Hey Oz. Your from Houston right? I went to school in Bellaire TX. I was in the autoshop class.

[@OzMechanics]

Yes sr. I’m on the southeast side. Awesome

[@rrmech11]

@@OzMechanics I lived in sharptown

[@lindseywhite7852]

Check the radiator fluid it will not blow cold if it is low had 2008 the dealer replaced everything it would not get cold until it checked and filled the radiator

[@jameslewis1175]

The control is a known issue in these but also i have had several aftermarket compressors with a bad sensor. I always just swap with the original

[@The_Touring_Jedi]

I have 9th Gen European model 1.8iVtec Civic. I did changed fluid and in the shop they told no leakage...but. I have a feeling that on outside ambient temp of 23-25°C it needs some time to blow really cold. it's 2014 model low mileage. Looks almost brand new. I have checked behaviour of compressor. If set to blow low at 17°c the compresor switch on/off in like 5 seconds delay. But if I turn auto on 17°C the compressor stay on whole time and it switches on cabine circulation only. I had newer car model with latest generation of refrigirant like VW and Mercedes has they blew really cold in just seconds. Civic has old refrigirant R134 do I guess it needs some time to blow really cold air.

[@renj6531]

you have the part number for the control unit. I think mines is bad because I replaced the blend door actuator and when I press the floor and defrost button the motor dosnt move I bench tested the motor and it worked which tells me its a control issue

[@OzMechanics]

Honestly I forgot. But if you call the dealership and give them your vin they will give you the proper part. It’s not crazy expensive

[@user-te3pn4pb4u]

i would say they were guessing cause they should have caught the pressure transducer hi pressure after they replaced it. so that tells me they did not check the original one as well ,cause they would have caught that to if it was hi or correct, i always gather the data before and after a repair cause you are always looking for a difference in data after a repair, if it does not change then you did not find your issue. that's why i say they were guessing

[@davidche554]

Hello I had a question why did you replace the ac switch without test the circuit of the switch?

[@OzMechanics]

I recorded that part but had no audio and scrapped that part. That’s why on the transition I just put a black screen and said customer agreed on the ac unit. Hope this answers your question

[@GraditelMacedonia]

Probably that sensor is good, but are opposed, for other system type.

[@sheerwillsurvival2064]

The rockets 🤠

[@OzMechanics]

Heck yea. I had basketball shorts and crocs on this video

[@sheerwillsurvival2064]

@@OzMechanics 👊🏻🤠

[@H8HotWeather]

I have a 2003 rsx I turn on the ac and it blows cold for a minute and then it blows hot. Any idea what this could mean?

[@The_Touring_Jedi]

Compressor sensor or high low pressure valve.

[@porky7753]

Great job Mr Oz, you deserve a ticket on the tequila train.

[@OzMechanics]

You know what porky. I’m down for another tequila trip

[@jonesy4588]

just normal for them

[@gautorepair]

chinesium strikes again bro! lol.

[@OzMechanics]

For sure. I think the aftermarket one was 18 and oem ran 96

[@gautorepair]

@@OzMechanics yeah thats the detail right there. The aftermarket prices are way too appealing. But when you get a bad one it all goes down the crapper. Has happened to me several times. It seems to me the pandemic made it worse.

[@hilariomartinez8220]

You should ask your customers what shops they did take there vehicle to become then you could make a list to show your viewers where not to take there vehicles because they don't have technicians that are worthy of calling themselves technicians I find it so hard to understand how people pay so much money on diagnostics just to have your vehicle returned in the same position or worse

[@OzMechanics]

This car came from another shop so I never really spoke to the customer. And I think this is the reason we as shops need to charge accordingly when it comes to performing a diagnostics.

[@nickayivor8432]

Enjoy your weekend with all your family around you, Oz Mechanics 👍 SHREWD, Oz Mechanics From Nick Ayivor from London England UK 🇬🇧 ⏰️ 23:52pm good night 😴 🥱

[@OzMechanics]

Thanks for stopping by Nick. Hope you are your family are doing great

[@larrystephens7437]

And the original problem was? Parts cannon.... Well done diag...

[@OzMechanics]

Lmao 🤣 parts canon booooom

[@Really658]

Aftermarket. Been there.

[@OzMechanics]

Yea. I’ve seen a lot of crazy stuff when it comes to aftermarket

[@avenger1888]

Oz I think the head unit was fine. The problem with the air conditioner is thaf someone dies kniw how to use it. I watched your video and not sure if others noticed but on the original head unit the air circulating button was high lighted not the air vents ( windshield vents or the cabin air vents. ) When you replace the head unit the compartment air circulating button was off and the air vents was turned on. If Im correct for the air conditioner to work you need to select the air vent NOT the circulation button. So I think everyone overlooked that and put parts and time into something that was simple just switching the control from circulating to cabin air vent.

[@OzMechanics]

That is wrong circulation button will not effect the a/c being on or off. You can try that on your vehicle. Hope this answers your question

[@edwardthayer9386]

Im willing to bet it never needed a compressor!🤦‍♂️