mustang stalls when comes to a stop w/ ac
Thread Starter
Joined: Jun 2009
Posts: 5
From: texas
mustang stalls when comes to a stop w/ ac
hi i have a 2001 bullitt rides great.but stalls when i come to a stop only when i have the ac on, ac runs good on the highway but coming to a stop and shuts the motor off . so i trun ac off and starts right back up ..ps...please help its hot here in texas
4th Gear Member
Joined: Mar 2009
Posts: 1,291
From: CA
The A/C compressor puts an extra load on the engine (mechanically, not just electrically). The computer is supposed to compensate for the added load by increasing the idle. Since your A/C system seems to be working than the GEM module and PCM are talking (which eliminates a possible communication error).
I would suggest starting the car (when parked) and turn on the A/C. You should notice a slight increase in idle speed (~300-500 rpm). It could be possible that the IAC (Idle Air Control) valve is clogged or malfunctioning. Most of time, however, a dirty IAC will affect idle quality ALL the time.
Usually a low voltage condition will cause many other features to not work properly. If you believe that the battery voltage is getting low enough to not operate the engine electronics- try turning just the headlights on, and than the high beams; and monitor the engine rpm. It should drop and than increase VERY slightly when idling.
You can always check battery voltage with the engine OFF at the terminals. And, you can always check the charging voltage with the engine RUNNING at the terminals OR at the back of the alternator (charging post) and a the negative terminal (the 2nd one is more accurate).
I would suggest starting the car (when parked) and turn on the A/C. You should notice a slight increase in idle speed (~300-500 rpm). It could be possible that the IAC (Idle Air Control) valve is clogged or malfunctioning. Most of time, however, a dirty IAC will affect idle quality ALL the time.
Usually a low voltage condition will cause many other features to not work properly. If you believe that the battery voltage is getting low enough to not operate the engine electronics- try turning just the headlights on, and than the high beams; and monitor the engine rpm. It should drop and than increase VERY slightly when idling.
You can always check battery voltage with the engine OFF at the terminals. And, you can always check the charging voltage with the engine RUNNING at the terminals OR at the back of the alternator (charging post) and a the negative terminal (the 2nd one is more accurate).
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