# Run Megasquirt = loose your air conditioning



## jk35 (Sep 1, 2008)

Someone tell me this isn't true








Is there anyone here on Megasquirt that has fully functional air conditioning (B5 TQM)
I have recently been informed that there is NO way to have air conditioning once you switch to MS


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## radics1 (Jul 31, 2008)

*Re: Run Megasquirt = loose your air conditioning (jk35)*

I dont know why cant you use the A/C with MS.The stock ecu uses just a signal from AC to keep idle at the desired value.Altrough if it is used to control the ac,you can make a semi-standalone config,splitting the signals ,and using only ms to drive injektors,ignition,boost control,etc...


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## mjleamy (Mar 16, 2004)

*Re: Run Megasquirt = loose your air conditioning (jk35)*

I have fully functional air conditioning with MS. MS has no effect on the AC. However, when the compressor kicks in, your idle can decrease quite a bit. The way I deal with this is to have a jumper wire from the AC clutch that opens a purge valve when the clutch is powered (i.e., the AC compressor is running). The purge valve allows more air into the intake, thereby increasing my idle speed. I got the idea on the MS forums. Works great!!!!!


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## jk35 (Sep 1, 2008)

*Re: Run Megasquirt = loose your air conditioning (mjleamy)*

Can you finish mine, load files and have me up and running? 97 058 AEB 1.8 20v in 1997 audi a4 B5 TQM running 3076r on a fully built (stroked) engine


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## mjleamy (Mar 16, 2004)

*Re: Run Megasquirt = loose your air conditioning (jk35)*

Contact need_a_VR6 for your application - he is the best bet. Basically, I have my 16V dialed in and so what I do is replicate my setup for others that are interested. In fact, the chump change I make doing that amounts to a charity effort (which is why most megasquirt builders eventually go belly-up, or worse, are sued in small claims court for taking orders/payments and not building units). For your setup, I would have to do a lot of background reading and investigating. It isn't worth it to me, and wouldn't be in your best interests. 
Good luck! It will be worth it when it is all said and done. Mike


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## jk35 (Sep 1, 2008)

*Re: Run Megasquirt = loose your air conditioning (mjleamy)*

as you've probably seen, I nailed up a FS ad here and in the classifieds on AZ... I'll look up needavr6 as you suggested, just in case it doesn't sell as quickly as I'm expecting. Even if it does sell, the buyer may need his (Or YOUR) services. I appreciate your time and advice sincerely.
My guess is it will go pretty fast at the price I am blowing all that gear out for. I'll probably throw up an eBay ad if it's still here in a couple days...


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## jk35 (Sep 1, 2008)

*Re: Run Megasquirt = loose your air conditioning (jk35)*

Kevin Black and I have a handshake deal on one of his fully programmed EMS's. Kevin has an excellent reputation. and every customer of his that i have actually spoken to has answered the same when I asked my ultimate question:
"If I were to GIVE you my car, signed title and all... who would you go to for an EMS/tuning?
all have answered "Kevin Black" -nuff said as far as I'm concerned
MS would have been really cool to finish and run, but I'm getting short on time, patience and money, and just want my car on the road.
I think a complete pre loaded EMS is best for me at this point


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## need_a_VR6 (May 19, 1999)

*Re: Run Megasquirt = loose your air conditioning (jk35)*

The only difference between MS and the stock ECU is an input from the AC system that makes the ISV a little more reactive. If you really tune the PID settings for the idle valve, it should be able to hold the idle with the AC on. If you have more specific questions about it let me know.


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## mjleamy (Mar 16, 2004)

*Re: Run Megasquirt = loose your air conditioning (need_a_VR6)*

PID = Proportional Integral Derivative. It is a classic control strategy where the feedback loop uses input corrections proportional to the error, the error integrated over time, and the time rate of change of the error. 
need_a_VR6 --- do you really expect a guy who can't get his MS up and running to know what PID is?


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## need_a_VR6 (May 19, 1999)

*Re: Run Megasquirt = loose your air conditioning (mjleamy)*

Should I have just said 'closed loop'







I was hoping there was some F1 information but on the file I have there isn't much info. There seems to be some details on msextra.com under MS2 development.


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## pac1085 (Jan 24, 2005)

I was never able to get my AC to work on my 97 unless the stock ECU was plugged into the throttle body.
When I had Megasquirt connected to the throttle body (for TPS signal) the AC did not operate at idle, and came on/turned off randomly (it seemed to only turn on above 3000 rpm or so, so only highway cruising)
It acted really weird, and I ended up ripping out the AC system when I replaced the motor.


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## Audi4u (Jun 29, 2002)

*Re: Run Megasquirt = loose your air conditioning (jk35)*


_Quote, originally posted by *jk35* »_Someone tell me this isn't true








Is there anyone here on Megasquirt that has fully functional air conditioning (B5 TQM)
I have recently been informed that there is NO way to have air conditioning once you switch to MS



This is partially true. The b5 uses one harness to connect to EVERYTHING on the engine, including the ac compressor, unlike the transverse setup that only connect to the the sensors required to run the engine.
If you convert to SEM by ripping the entire harness out, the ac will not work. If you splice into the harness then everything will work normally.
http://****************.com/smile/emgift.gif


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## radics1 (Jul 31, 2008)

*Re: Run Megasquirt = loose your air conditioning (Audi4u)*

I solved the problem,check out my thread here! (AEB to MS)


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