The problem is with the A/C, if I have it on while Im driving, my van or more specifically, the engine "jerks", almost like its changing gears (which its not). It happens frequently & is pretty scary
Anyone have any ideas
Off hand it sounds like normal cycling of the compressor. AC compressors in "cars" don't run continually, The compressor runs and fills the receiver then shuts off, the receiver partially empties and the pump turns on again.
Thumbnailing this, it takes 30 horse power (more or less) to maintain a highway speed, and it takes 5 horse power (more or less) to run the AC pump, so when your going up the highway and the compressor kicks in there is a sudden 16% reduction of power (5 hp) going to the drive wheels.
Around town the starting of the compressor is much more apparent because the engine is making less power.
Wife comes home one day and says her car is acting funny so I take it for a drive. The compressor kicks in and she says "there it is". How Husbands learn to keep our mouths shut ... she'd had the car for 5 or 6 years.
Many times there are things that are going on that have always gone on it's just that people haven't noticed it.
It could be a lot of things from a vacuum leak to a compressor starting to seize up on you.
Then theres that, the compressor could be starting to seize making it's activation more noticeable.
Back in the days of carburetors there was a solenoid that would activate when the AC compressor started that would keep the car from stalling. Usually. {Chuckle}
Thumbnail: With computer cars when the compressor starts the 'idle control valve' opens a hair and the injectors dump a bit more fuel. Whether this happens above idle would depend on the car, the computer and the program.
The AC system could be functioning just fine but now your noticing the starting of the pump because engine management isn't bumping up the power when the pump starts. That could be caused by a lazy IIAC, or a broken wire resulting in the computer not knowing the AC is on, or a failing sensor could be allowing the program to fall off it's map, or, or, or, or ....
Or it could be you just started noticing the compressor starting.
Thing about 'trouble shooting' via web is we could speculate all week and not come close.
Catch
Car Talk on Saturday, Tom and Ray have been fixing cars for decades and at times the best they can do is throwing a dart or flipping a coin.
AC systems can be complicated but without knowing what van you have I suggest you drive it till is starts with the jerks then get it checked via a computer read out.
AC systems are pretty straight forward, it's the way everything is tied together that causes madness. LOL!
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With that being said, I wonder if anyone here can help me out, I really dont want to take it in to be checked out without having a little knowledge of what could be wrong.
I havent had it for almost a year!
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