So my AC when at idle doesn't blow cold (I believe DrivenFab said it doesn't appear to actually be cutting on). WHen I start driving it blows cold as hell. Now here is the weird thing.....when you put 12v directly on the compressor it kicks on and blows cold.

I thought there was somewhere in the ECU to trigger the Compressor to kick on but I don't see it. Anyone else have this issue or know a fix. I don;t think its the AC clutch because it works when the car is in motion and it works when power is applied directly to it.

I don't think its the wiring because like I said it works fine when the car is moving. Its as if whatever is supposed to tell the compressor to turn on when I'm stationary doesn't send a signal until I'm moving.

 

Second problem: Car overheats when the AC is on when on the highway. In stop and go traffic its solid. Never overheats or anything no matter how hot it is.

Put a better fan on and it helped....and wired it up to switched power. Flushed the coolant system, no thermostat, lower thermostat. Water wetter and water, straight coolant, no shroud with a shroud. Somethings improved......sometimes it doesn't do it, most time it does.

At this point I'm considering replacing the Koyo with a ToxicFab (reached out to CBRD and I'm still waiting on Chad's ideas) thats about the only thing left for me to replace.

Unless someone has a better idea.

 

How about your mod list. Did you take the a/c fan out? have you considered that you might have a blown Head gasket? You running a 1/2 size radiator? Just asking so we can get a base line and figure out the issues.

 

I'm having the same issue with a/c not coming on at speed 0. When car is coasting to a stop a/c is still blowing cold. When I stop, a/c compressor shuts off. Compressor not on at any rpm at speed 0.

It started after I was tuned on tefra v7. Try flashing in a stock rom and see what happens to your a/c issue.

As far as it over heating on the highway, put the thermostat back in. There's a chance that the coolent isn't spending enough time in the radiator to cool down.

 

Currently it has a lower tstat in it. It didn't before but I have been through so many different changes I guess it would be worth it to try without the tstat.

I'll flash an stock rom and see if it kicks on, have you tried it?

If it started with Tephra V7 then I'll try and see if anyone else complained about the same thing in one of the threads.

 

First, a disclaimer - I'm no A/C guy.

The refrigerant also cools and lubricates the compressor. If the refrigerant is low the compressor can toast. To protect the compressor there's a pressure switch. So, I'm thinking that when driving the compressor is running fast enough to maintain sufficient pressure to close the switch but not at idle. When the switch is open the clutch won't kick in. I know this doesn't explain how it kicks back in again when driving.

As for the overheating problem, scan the ECU for coolant temperature. Wiring problems under the hood (a bad ground) can make the gauge read wrong.

I wonder if there is a Tephra mod that kills the compressor if the engine overheats?

 

Doesn't overheat at idle or stop and go.

The AC system has been bled and refilled a few times already. I'll have it done one more time next week.

I did find this: Periphery on ECU Periphery4 (FEA) Bits, Bit 11 shows P1530 A/C1 Switch.

What does that control? Its about the only AC related item I could find on Tephra.

 

Just have the pressure checked. No need to refill if not needed.

 

I will and will report back.

 

Disclaimer - I work on cars for a living.

There is no way this is an A/C pressure problem. If the pressure was low, the compressor would never come on. The compressor doesn't come on unless the computer grounds the relay for the A/C clutch. If the refrigerant pressure is too low or too high, the duel pressure switch will interrupt a power coming from the A/C-ECU to the ECU, and thus not let the ECU ground the relay for the compressor clutch.

I have checked everything in my A/C system. It works well when the ECU tells it to come on. I have checked and rechecked. I have filled the system to spec. It still doesn't work at speed 0. A while back I reflashed my ECU with my "as bought" non tephra tune. It barely ran, but the A/C clutch came on at speed 0.

I have been trying to get in touch with the tuner to see if we can figure this out, but as of right now, he has not yet responded to me. I tried to get AWD Motorsports here in FL to help me out......mind you I was looking to get retuned and to figure out some slight issues with how my engine is running and possibly get different cams done at the same time.....I was told that it wasn't in there best interest to tune my car because they didn't build the engine or tune it the first time. This was just from a phone call. They haven't even seen the car. This has royally pissed me off. I don't often ask for help when it comes to cars. I don't want to learn to tune them. I was going on a cruse. I wanted to drop my car off before I left, pick it up when I got back and have it tuned by one of the premier EVO shops in the US. I'll end my little rant here as this isn't my thread to rant in.

 

LOL. There is some liability in tuning something with an unknown history. That being said i've never seen a shop decent or otherwise refuse to tune a car just because they didn't build it. Interesting. Who tuned it first (That may have a LOT to do with it).

I figured it wasnt a pressure issue. Especially since when you put power on the compressor it clearly turns on. Its as if the ECU is not sending the signal to Compressor to turn on even though its set to be on at the HVAC controls. I haven't gotten a response from the ecuflash forum on if the periphery bit I found is key. It seems to make sense that the ECU is what the issue is and if someone with some disassembly knowledge would give me an answer about the ECU controlling the AC compressor at idle and can it be flagged to be on or off then at least i can chase another avenue for a solution.

All of the suggestions I've gotten assume there is something wrong with the compressor or wiring but clearly everything works when the car is rolling and the compressor works when powered by an independent source. My symptoms contradict conventional wisdom it seems.

 

Liability? What? When was the last time you put any of your cars on a dyno and didn't have to sign away every ounce of liability to the shop? You know the drill, list all your mods, how high do you want to rev it, sign here saying "if anything goes wrong, oh well." Oh, and that will be $50-$700. Pay now.

I was tuned at PRS. Aside from the tuner not getting back with me still (only been 10 days) I had some decent customer service there.

After being told by AWD they didn't want to tune my car, the phone was handed to the tuner. We talked for a bit and Derek said he'd look over the tune at least. I e-mailed my ROM to him and he looked at the tune and said it was pretty good. He also said he'd get back with me about trying some things out with the rom to see if we could get my A/C working. He has yet to get back to me on that, even after I e-mailed him again on topic. That was on 6-19-13.

It's been the biggest slap in the face I've had with a shop. Just tell me my minuscule amount of money to be spent isn't good enough because I'm not dropping 30k on some GTR build. Tell me something, anything other than "it's not in our best interest to tune your car because we didn't build the engine." Chances are most shops didn't build the engines in the cars they tune. That, and it was just assumed that PRS built my engine. They did not. But I was never asked that either.

 

I feel you brother. There are some other shops I'm familiar with that seem to have "forgotten" evo owners and have gone on to more lucrative car platforms (Skyline, Gallardo, etc). It doesn't help that as this platform has gotten cheaper more people who can't afford to do things right are scooping the cars up and expecting cheap service to go along with.

I'm reaching out to a few other tuners as well to see if anyone has an answer. I feel there is something in V7 that controls the basic function of having AC compressor turn on at 0 RPM's but until I get confirmation either way this is all educated (or non) guessing.

 

I have the same problem with my ac. I was thinking it was my condenser or even the fan. Is there a noise coming from your condenser fan/condenser?

 

When I turn on my a/c at idle, my condensor fan comes on and my engine idles up. All things that should happen except compressor comming on.