A/C turned off in the tune????

[06JET]

Hey guys, I have a question for you. My A/C was working fine last summer but this winter i did a lot of mods to my car and started with a new tuner this spring. The tuner is great but on the first start up my A/C doesn't work. The compressor won't come on. The pressure is at or close to the ambient temp when equalized. What do you think. Tuner issue??

 

[07 Boss]

have you tried to jump or bypass the relay to get it to come on. I know that it is disabled at WOT. I don't see why a tuner would shut it off unless it was by accident. I would look for something mechanical/electrical before looking at the tune.

 

[BruceH]

Did you plug the a/c pressure sensor back in? It's real easy to miss it. It's close to the radiator on the drivers side.

 

[06JET]

I did make sure the plus are all connected.
OK, so - is the switch behind the motor the one you jump/bypass the wires on to get the compressor to run? I was reading that the one up front by the radiator doesn't do it. I believe the pressures on the high and low side when equalized are normal. I believe it should be at or up to 10psi above ambient temp. I only say that because I don't believe I have a leak. I did move some wires around pulling the valve covers off to change the cams out. I will double check the wires and connectors. it's just weird that when I shut it off last fall it worked and after 4 months of mods and winter when I started it back up with the new tune everything works perfectly except the A/C. I just did not want to start pulling things apart and messing with it if the tuner could accidentally have it turned off.
The emissions computer readout has a box for the A/C Refrigerant and it says "not supported". We have been working on it passing emissions lately. I have had it checked at the test facility about 4 times already only to FAIL!! I believe it will pass the next time I take it in.

 

[408Stang]

I think you either have low pressure in your a/c system or the pressure switch is not working or plugged in. I'd start with the sensor on the driver side down by the ABS and radiator.

Then check the plug on the compressor which activates the magnet in the compressor pulley and engages the clutch.

Lastly, take the car to a shop with an A/C recirculation machine and check the levels / refill.

I doubt the tune has anything to do with it.

 

[redfirepearlgt]

^^^ First thing I would check AGAIN would be this pressure sensor connection. Brenspeed missed putting this back on after doingthe cams on my 2005 many years ago. I first thought I had low coolant or that they had nicked pressure line, but turned out to be the low pressure cutout sensor was never plugged back in. It is exactly where 408stang described it. If it is in fact connected, do not try to bypass it without first checking to see if you are low on 134a refrigerant. To my knowledge there is no way to bypass the AC unit through the tune. Pretty certain all the PCM cares about is whether the AC compressor is running or not. Someone corrrect me if I am wrong. I am going on a common sense hunch on the last statement.

 

[06JET]

OK, I have unplugged all the connectors and cleaned them with spray type electrical connector cleaner and plugged them back up. 3 places - by radiator, back of engine and the compressor. NO CHANGE. Any other places with connectors that I can check? Those are the only ones I can see. How can I check the switches? ohms? voltage? Do I jump it at the switch behind the motor? Take the plug off and insert a paper clip?

 

[408Stang]

I wouldn't jump anything... It sounds like you have low pressure in the lines. The pressure switch is like the ignition key to the a/c system... If it doesn't see adequate pressure nothing will work... That's how it saves your compressor from destruction.

I assume you've checked fuses too?

 

[Pentalab]

It's most likely the tune. A buddy on the Roush forum had his 2010 vert, with a M90 and new tune from VMP. His is an automatic. He takes it into local ford dealer, and no way in hell could they figure it out. AC would not come on. In desperation, he loads his older JDM tune ... and presto, AC is now working. Swap back to the VMP tune..and AC went dead.

I had VMP tune my 2010 Auto ( same M90 blower)...and presto, my AC went dead. Notified VMP, and got a revised tune, fixed in 3 mins flat.

Then a year later, a fellow from the caribbean complains his 2010 auto, ( M90 blower) with a new tune, AC went dead. ( different tuner, forget who). Same deal, something in the tune got missed. Dunno why it was always a 2010 auto with M90 blower in all 3 x cases. Easy fix though. There is some table or similar in the tune somewhere, that turns the AC on /off. Start there, b4 you tear your hair out.

 

[redfirepearlgt]

It's most likely the tune. A buddy on the Roush forum had his 2010 vert, with a M90 and new tune from VMP. His is an automatic. He takes it into local ford dealer, and no way in hell could they figure it out. AC would not come on. In desperation, he loads his older JDM tune ... and presto, AC is now working. Swap back to the VMP tune..and AC went dead.

I had VMP tune my 2010 Auto ( same M90 blower)...and presto, my AC went dead. Notified VMP, and got a revised tune, fixed in 3 mins flat.

Then a year later, a fellow from the caribbean complains his 2010 auto, ( M90 blower) with a new tune, AC went dead. ( different tuner, forget who). Same deal, something in the tune got missed. Dunno why it was always a 2010 auto with M90 blower in all 3 x cases. Easy fix though. There is some table or similar in the tune somewhere, that turns the AC on /off. Start there, b4 you tear your hair out.

I'll be dagged. Would have never thought the AC compressor could be deactivated in the PCM. Just figured the PCM needed to know when the AC unit was commanded on. Interesting. Must clearly be a rung of ladder logic(for no better term) for that as well as run status of the compressor. Thanks for the correction.

 

[408Stang]

Please report what you find out.

I will say that I once had a problem with my cruise control being turned off in a tune, so I guess anything is possible.

 

[06JET]

Thanks for the input guys. My problem is that I don't have an old tune to put back into it. It was dyno-tuned before I got it and the Diablo tuner is empty (no custom tunes) that I got with the car when I bought it. My tuner says that he is sure that the tune does not have the A/C turned off. He has done a great job but I wonder if he took the time to actually check it out when I asked him (twice so far). I'm trying to figure it out myself before I go back to him and piss him off. He is one of the best and I trust him but this is not making sense. I would like to be able to check out the pressure sensors myself but I can't find out how. I don't want to go just replacing things.

 

[redfirepearlgt]

I actually spoke to my tuner at VMP today about datalogs I sent him and as an opportunity for learning asked about this. I realized half way into his explanation that obviously the AC would be controlled via PCM since the logic is written to shut the compressor off at WOT....DUH! Brain farts do hurt sometimes. He did state that they have inadvertently done that by accident and that it is a mere change that takes a few minutes to resolve and email. I sure do miss having electrical prints and Shop tech manuals like I had when I had my 2005. Best $100 I ever sent on ebay. Gave them to a friend when I traded it.

 

[BruceH]

I actually spoke to my tuner at VMP today about datalogs I sent him and as an opportunity for learning asked about this. I realized half way into his explanation that obviously the AC would be controlled via PCM since the logic is written to shut the compressor off at WOT....DUH! Brain farts do hurt sometimes. He did state that they have inadvertently done that by accident and that it is a mere change that takes a few minutes to resolve and email. I sure do miss having electrical prints and Shop tech manuals like I had when I had my 2005. Best $100 I ever sent on ebay. Gave them to a friend when I traded it.

Would the 2011 manual be of help?

http://iihs.net/fsm/?dir=499

 

[redfirepearlgt]

^^^ I'll check it out. I also had the electrical prints which were awesome. Having actuals and not some conceived idea of them that are in Chiltons and Hanes are very handy when troubleshooting. It will likely cover most things that did not change on the 13.

Time lapse...

Nice. I enjoy having paper form better for taking notes on and highlighting, but this is nice to have access to. Thanks Bruce. And there is no worry about tearing pages. LOL!

 

[BruceH]

^^^ I'll check it out. I also had the electrical prints which were awesome. Having actuals and not some conceived idea of them that are in Chiltons and Hanes are very handy when troubleshooting. It will likely cover most things that did not change on the 13.

Time lapse...

Nice. I enjoy having paper form better for taking notes on and highlighting, but this is nice to have access to. Thanks Bruce. And there is no worry about tearing pages. LOL!

Thank Louie in Dubai, he goes by G.T on this site and maintains the Mustang manual site.

Loads of good info there.

 

[Sky Render]

Is there any easier way to download that thing other than clicking through to every single page?

 

[06JET]

Nice. Thanks for the link.

 

[06JET]

Any tuners out there that know what it is called in the tune that turns off the A/C? A certain file name or section of the tune? Emissions test sheet says "A/C refrigerant not supported"

 

[redfirepearlgt]

scratch - Just found an 05 schem and they are quite different. Sorry - will write up again.