alexkharden

I have a 2010 Honda Civic EX, automatic transmission.

My AC wasn't blowing cold, so I took it into the shop that have it checked and charged. It was about 5oz low, so they filled it, but when the tried to test it the compressor wouldn't come on.

They checked all of the fuses and relays, all good.

They rechecked the freon pressure, full.

They checked the codes, no codes.

They checked the computer, receiving and sending AC on/off signals correctly.

They turned the system on and jumpered the compressor, and it kicked on like it should.

So they tell me I need a new compressor because there's a switch down inside it that isn't kicking on when it receives the signal to go to "ON".

Does this sound right? The AC worked beautifully at the end of the warm season last year, but now suddenly does not. Is this switch a known or heard of issue? Am I getting scammed into buying a new compressor and having it installed?

Anyone have any thoughts or ideas? Thanks in advance!

Edit: Added additional info

jordan1794

Did they check at the compressor for power?
The computer might be sending, but the compressor might not be getting...
Wire could be eaten up by rodents and what-not. Connection could be corroded somewhere, etc.

I'm sure someone with more knowledge will be in soon to give a better insight.

ezone

Does NOT need a compressor (yet).

You need a shop with a competent tech that can diagnose the true problem.

If you think you want to try to tackle some of it yourself, I can try to help......

alexkharden

I assumed they did, but it was never actually said that they did.

The question I asked them was,"If this switch is bad, then how is it actuating at all - whether by jumpering or directly connected?"

They replied, "Normally the switch uses 8-10v, but when we jumpered it we were putting 12v on it. Apparently that was enough to force it to actuate."

Now, I'm not an electrical expert by any means, but it doesn't strike me a valid to assume that a switch that won't actuate at 10v will suddenly, magically, actuate at 12v.

Am I wrong?

alexkharden

I am definitely going to try to tackle some, or all of it myself - given that I don't have the $625 they quoted me to replace the compressor, nor do I have the cash to continue taking it to places and having them charge me to diagnose it. So yes, any help would totally be appreciated. I'm mechanically inclined, and have worked on my own cars for years, but have never delved into the a/c system at all. (This is actually the first car I've ever owned with an a/c that ever worked).

ezone

You have an electrical issue at the moment.

How many miles are on the car?


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Start the engine, turn on the AC system.

Does the AC indicator light on the HVAC panel light up?

Does the interior fan work?

Do the radiator fans come on?

Can you tell (visually or audibly) if the compressor clutch kicks on?




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Do you have a volt-ohm meter, and do you know how to use it?
12v test light?

Do you know how a relay works?
Do you know how to jumper (bypass) a relay socket?

alexkharden

The car has ~115k miles

Yes, the AC indicator light comes on.

Yes, the interior fan works

Yes, the radiator fans come on

No, the compressor clutch does not appear to come on (not to sound stupid, but the compressor clutch engaging would mean that the center of the pulley on the compressor starts spinning with the pulley, correct? If yes, then no, it's not spinning)

Yes, I have a 12v meter, no 12v test light

To my understanding, a relay is a switch that actuates another switch. Power comes in the control circuit, which activates a magnetic field that closes the load circuit. To jumper that I should need only know which two pins are for the load circuit, I assume.

ezone

K, K.

The system is attempting to operate. Control panel is ok, there is sufficient pressure in the system to make it engage, the PCM is receiving the AC request and is operating the radiator fans, and should be trying to turn on the compressor.....

Correct.

Yay, we are cooking with gas now!


Start the engine, turn on the AC system. Radiator fans should be running.

Locate the AC clutch relay in the engine compartment fuse box.
Hit it with the something like the handle of a screwdriver.
Does the compressor kick on?

Clutch relay is #1 in this diagram
(ignore the CRV part, it uses the same box)





If it kicked on when you tapped on it, the relay is bad. STOP!
Replace with updated MITSUBA version, and I can give you the Honda part number to ask for.



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If it did not kick on, then pull out the relay and test the terminals in the socket,

Micro relay diagram below: Terminals 1 and 2 are for the coil, 3 and 5 switch the load.


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Socket: Terminals 1 and 2 should test as a power and a ground (can be either way).

Terminals 3 and 5: One should have +12v battery power, the other should test as a ground (it will go to the AC clutch, and should measure around (GUESS) 3-4 ohms resistance as measured between the terminal and battery ground).

If you jumper 3 and 5, the clutch should click on.

alexkharden

You are a god. Seriously.

I tapped the relay and holy of holies, the compressor clutch kicked on. But no, I'd rather pay $625 for a new compressor. (sarcasm intended)


I tapped it twice and the compressor kicked on immediately. Got into the car and within seconds the air was ice cold. So it seems reasonable to me that all I need to do is get a new relay, correct?

Hopefully this is something I can pick up at autozone, or is this a special order/dealer item?

ezone

Not really, I just play one on TV.


Bingo! Gravy!
And that's probably for a crappy Four Seasons reman compressor ---- that will only last 4 seasons. Or less.

OR MAYBE they really did figure out the relay problem and would collect $625 to replace it, hoping you would never know if the compressor got replaced or not.
Or maybe replace the compressor then not figure out why it STILL doesn't work.
IDK.



You need a new shop. With people that actually fix cars on purpose, and bill accordingly.

Correct.

You can get cheapo relays at the parts store, but you may face more problems.
I'd spring $20 for the improved/updated relay from the dealer.

Tell the dealer parts department you need part number 39794-SDA-A05.
Brand name of the updated relay will be MITSUBA.
MSRP is $19.18. (If they price it higher, they may come down if you know the correct real price. If not, mail order is an option.)

Your original relay should say OMRON on it.


HTH

alexkharden

Awesome, thank you so much!