R34 GTT AC not working - compressor not starting

[GoHashiriya]

Hi all, 

I noticed last week that the AC stopped working, we've just come out of winter and it is most noticeable now. That said, how long it has been non-functional for is beyond me - last summer it worked fine.  I didn't notice any issues up until December, then the car was rarely used over the winter.

When I say not working, the green AC light illuminates but the compressor doesn't start. Blowers are fine.

I've ran through the diagnostic procedure, nothing under step 2, I just get 20. No issues under step 3. Under step 4, it cycles through the different outputs, just no actual AC. 

I checked the the cabin air temp sensor next to the steering wheel, just in case I disconnected it when installing the alarm recently - it's fine.

All fuses have been checked.

I have tested the relay, it's fine - there is 12v to pin 1 and (I think) 3. However, the relay does not click when the AC button is pressed. Also, from prodding the compressor wire, there seems to be no 12V under any state. I'm guessing the ECU is not grounding the relay.

My question is, what are the likely causes for this - no gas (unfortunately this is something I can't check until next w/e), or sensor? A little direction would help a lot. Japan is getting hot AF.     

[GoHashiriya]

I should mention that there is no change in engine RPM when the AC button has been pressed.

I will try bridging the pressure switch if necessary once the gas status has been confirmed. 

Edited April 10, 2022 by GoHashiriya

[BK]

Maybe stuffed relay then ? Test the relay external to car first.

[GoHashiriya]

On 4/10/2022 at 6:59 PM, BK said:

Maybe stuffed relay then ? Test the relay external to car first.

Ordered a relay today (also arrives today 😀), along with a new pressure switch - it was cheap okay.

Did the bypass-the-relay trick this morning and compressor fired up, had cold air, ran it for a couple minutes then shut it off just in case any damage would be caused.

I did not notice the usual high-rpm adjustment, but it can be tricky given that the car was warming-up and I run an Auto ECU on a manual that's kind of all over the place around idle.

Mechanic will switch out the pressure switch and re-gas the AC system this weekend. Im under the assumption pulling the pressure switch will release gas. Then we'll go from there.

I bottled-it when it came to bridging the pressure switch as there were 3-pins and I didn't know which to bridge. Pin 1 was earth and then the other two went to the ECU. 

[GoHashiriya]

Sorry, I should have mentioned the relay has been tested (out of the car) and it seemed fine. However, I did read a post by someone in an earlier thread mentioning they tested relays, they tested okay, then tried a relay from another car which solved the problem. 

[BK]

On 11/04/2022 at 3:55 PM, GoHashiriya said:

However, I did read a post by someone in an earlier thread mentioning they tested relays, they tested okay

Crap - A relay works or it doesn't. The contacts are good or they're not. When you say tested out of car, you mean you put 12v on the coil to activate then tested for 0 ohm across contacts right ?

[trel]

If there's no gas or very low it won't kick on at all hence no change in revs. Check gas first.

[BK]

On 11/04/2022 at 5:06 PM, trel said:

If there's no gas or very low it won't kick on at all hence no change in revs. Check gas first.

That's right - pressure switch has to be activated or relay won't work.

[joshuaho96]

If it is low on refrigerant definitely do not just recharge and keep going. Leaks let moisture into the system which is a good way to saturate the receiver/drier with water and start damaging the compressor and other components with internal corrosion.

[GoHashiriya]

On 4/11/2022 at 4:27 PM, BK said:

Crap - A relay works or it doesn't. The contacts are good or they're not. When you say tested out of car, you mean you put 12v on the coil to activate then tested for 0 ohm across contacts right ?

No, not that specific. I mean I applied 12v to it and listened to it click. Well, good to know I should be doing it that way for future reference.

Just picked up the new relay from Nissan so the relay will get replaced anyhow. If no change, I'll just keep the old one for a spare. 

On 4/11/2022 at 5:34 PM, joshuaho96 said:

If it is low on refrigerant definitely do not just recharge and keep going. Leaks let moisture into the system which is a good way to saturate the receiver/drier with water and start damaging the compressor and other components with internal corrosion.

Also good to know. I'll try and look over the system for any leaks - from the front there is nothing visible but I realise it goes back toward the cabin. Are there any famed spots to pay attention to? 

I won't be able to progress with this until the weekend.

[GTSBoy]

A refrigeration mechanic is the only person allowed to work on car AC and they should not mess around. They should pressure test, vacuum down, recharge and dose with correct amount of correct oil. They should put in dye if there is any suspicion of an ongoing leak.

[BK]

On 11/04/2022 at 7:46 PM, GTSBoy said:

A refrigeration mechanic is the only person allowed to work on car AC and they should not mess around. They should pressure test, vacuum down, recharge and dose with correct amount of correct oil. They should put in dye if there is any suspicion of an ongoing leak.

In Australia absolutely yes, but not sure what it's like over there. In the US they can go the Repco equivalent and buy cans of R134A !

[GTSBoy]

On 4/11/2022 at 7:16 PM, BK said:

In Australia absolutely yes, but not sure what it's like over there. In the US they can go the Repco equivalent and buy cans of R134A !

'Murica! f**k (the ozone layer) yeah!

My guess is that Japan will be like here. They may still eat whale meat, but they're pretty tight on a lot of climate/pollution regs, etc.

[GoHashiriya]

On 4/11/2022 at 11:04 PM, GTSBoy said:

'Murica! f**k (the ozone layer) yeah!

My guess is that Japan will be like here. They may still eat whale meat, but they're pretty tight on a lot of climate/pollution regs, etc.

From my understanding Japan is more like the US. When searching the Japanese sites there were posts encouraging you to DIY it with a can. Is my mechanic a qualified AC guy, probably not, but he's nice enough to speak with me in Japanglish and seems pretty honest, so what can I do..

Japan has tight regs but operates on an honesty-based system, sort of like a "you can do this, but don't do it". And guess what, the regs are loosely enforced. 

Engine oil goes in the trash which differs to the UK.

[GoHashiriya]

We just topped it up with gas and it works fine. But that doesn’t rule out a leak. We haven’t found anything yet.

[GTSBoy]

Add dye.

[joshuaho96]

On 4/15/2022 at 6:35 PM, GoHashiriya said:

We just topped it up with gas and it works fine. But that doesn’t rule out a leak. We haven’t found anything yet.

Easiest way to find it is to pressurize the system with nitrogen and see if it loses pressure. Or pull a vacuum and see if it loses vacuum.

[GoHashiriya]

On 4/16/2022 at 11:35 AM, GTSBoy said:

Add dye.

Tried. Mechanic doesn’t have it as he’s not an AC specialist. Best course of action is to find an AC guy, or just come back in a few months and get him to check the pressure 

[darkhalf]

Bit of background on this. The R34 ECU takes input from the condenser pressure sensor, and the AC switch. When both are within range, then it triggers the AC relay (you can view this in CONSULT). Makes life interesting for NEO swaps if you want to keep AC running. If it stops clicking the relay, its lost pressure again

[GTSBoy]

On 4/16/2022 at 3:48 PM, darkhalf said:

Makes life interesting for NEO swaps if you want to keep AC running.

Hi Matt! I still don't know exactly what Brenton ended up doing to make mine work! Never saw the final wiring diagram, then got distracted.