Air Conditioner and Idle

[00GTpony]

Whats up guys, i have a pretty smooth idle just sitting there in neutral , but then the second i turn the a/c on the light constanstly bounces up and down.. like it will rev to 1800 then drop to 500, then right back up to 1800 over and over again, same wen i put the deforster button on... any ideas?

New iac already, cleaned throttle body, and cleaned maf

 

[lvmustanggt]

I had same problem, refill a/c. Problem solve

 

[Superhereaux]

when was the last time you had an a/c service? might be low on freon or your a/c fan might not be working, high pressure in the system might put more strain on the compressor

 

[thomas91169]

does it still blow cold when turned on? how is driveability or the rpm's during constant cruise with the a/c on (freeway cruise at ~1500-2000rpm)? does it take a while to get cold? as much as i hate the stealerships, when it comes to AC crap and all homebrew methods of repair fail, id just take it to them. if it costs too much to repair you either 1) dont need/want a/c enough to warrant the cost, or 2) just stop using a/c

 

[the98stang]

If it is still blowing cold, it's the cycle switch. If not, you have a leak in your AC system somewhere. Any A/C shop can evacuate the system and fix the leak. Problem solved.

 

[00GTpony]

How do i check fluid levels on the a/c ?

 

[the98stang]

How do i check fluid levels on the a/c ?

You need special gauges for the job. Try shorting the cycle swith by connecting both prongs together with a paper clip. Do this for only one minute, or you can fry the compressor. If the idle stops jumping, then the cycle switch needs to be replaced. It is located on the firewall, passenger side. It looks like a miniature cigar sort of.