defiance

So its getting hot outside and its time to use ac again. On the way to work today i turned the ac and something just isn't right. First of all, when the ac kicks on the idle drops and makes the whole car vibrate, horribly and i mean bad ( while the car is in gear). Second when the ac kicks on, the click is very loud and it keeps clicking several times within one minute span. Im a noob at the ac system but i think thats the compressor kicking in and out?
The car is a 4.0 auto with 83.000 miles on it. The ac air is not very cold but its no too hot either.
I disconnected the battery and followed the procedure for re-learning the idle, but that did not help any. I did a forum and internet search on this and really have not found a definite answer. Obviously my car has no warranty and i don't have the time right now with school and work to put it in the shop. I need you help guys to diagnose the problem and hopefully fix this with the least amount of money wasted.

Thanks in advance.

Nuke

That could be a number of things but first you need to rule out a malfunctioning AC. If you're getting enough cool air while cruising (or sitting with the idle above 800 - 1000 RPM) then we can probably rule out the AC itself.

A low idle when the AC is on makes me think that the engine is having difficulty maintaining idle at spec with the added mechanical and electrical load of the compressor. Are you experienceing any other symptoms w/o the AC on such as an erratic idle, hard starts, etc? I'd first do the basic PM (Preventive Maintenance) items related to ignition and fuel delivery before I start thinking about a trip to the delaer. Try cleaning the TB, replacing the fuel filter, replacing plugs, new air filter, fuel system cleaning (a tank or 2 treated with SeaFoam or Techron), etc. Often, it's just a minor issue but some greedy shop may charge you to replace uneccessary parts when all they did was wipe down the TB.

AzPete

With the compressor kicking on and off....I would guess you are low on refrigerant. You can buy the right stuff from local parts stores and add it yourself but if you do not have the pressure gauges and vacuum pump, it could cause a problem. I would say to take it into a shop for A/C's and have it checked. If there is a leak, they can find it plus service the unit. If not that.....leave it off and be without.

There is an in line switch that shuts off the compressor if the system is too low on refrigerant so you may be right at the edge of that limit.

defiance

No other symptoms that i know of, starts up and idles fine with ac off. Nuke, im gonna try to seafoam it like you said in my other thread concerning the sputter while idling. My TB has been cleaned and fuel filter is has been recently changed. I may take it to the shop like AZ said and at least let them check my refrigerant level. How often does a normal compressor kick in? Could all this have anything to do with the compressor pulley? Maybe its seizing up when the AC kicks in?

AzPete

The number of times the compressor "kicks in" is based on the temp setting on the inside and how it is cooling. The hotter the weather, the more the compressor stays activated, the colder the setting inside, the more it stays activated. If you turn the temp towards a warmer setting, it will allow the compressor to cycle on and off. If the compressor was seizing....it would have stopped turning and smoked the belt.

Sounds like you have an issue with the idle that is not connected to the A/C unit. Solve one at a time......makes life easier.

Nuke

PLEASE, follow the directions on whatever fuel system treatment you use. Too many folks don't: 1) use the proper ratio of cleaner-to-fuel and 2) don't add the cleaner AT THE PUMP BEFORE FILLING THE TANK.

Someone here recently added a bunch of fuel system cleaner to their 1/4 full tank (without topping it off) and couldn't understand why their engine died a few miles down the road. Duhhhh.....

TheYeti

Does it sound like plastic on plastic right under the dash?

MustangMan1718

I'm not certified on A/C at work, but I have been there for 3 years now, and have personal experience with having the service done to my car ($150.00 service for free is sweet).

One way to check the refrigerant level is to press a tool on the low pressure side. It will have a gauge that can be read based upon how much pressure is in the system. Usually if the needle doesn't move, there is a leak in the system, and we are unable to do the service. It could also mean that you are just extremely low on refrigerant though.

And if you happen to have a Valvoline Instant Oil Change around you, I would recommend stopping by there. We do our A/C checks free. We also have 3-part fuel system cleanings (only 2-part for our cars since they have electric throttle bodies and spraying them with the cleaner can damage that). In our market they are $59.99 and come with a money-back guarantee if you don't notice a difference in gas mileage or it getting rid of your rough idle. We can give discounts to make sales, so you can attempt to ask for $10.00 off too.

And finally, I don't mean to sound like a salesman, but this is just how I would get things checked if it were me. If it is something bigger than than such as a bad compressor, an actual shop would have to look into that. The employees may have some idea of what it could be as well.

defiance

Not sure if its plastic on plastic, ill have to listen tomorrow to make sure, its just very loud. Unless its always been like that and i have never paid attention.

Nuke ill clean the fuel system the next few days and report back. And Mustang Man i have 3 Valvoline Places around me so i will definitely swing by if all else fails, and if nothing else to check my refrigerant level at least, so thanks for the tip.

TexasTanker19kilo20

IF the compressor is clicking on and off quickly it's called short cycling which means you are low or out of freon. Also you said it doesn't get cold or hot, there is a low pressure switch which will turn off the compressor. If you can find a sight glass in the line look to see if it has bubbles in it(not sure if your model has a sight glass), if it has bubbles it's most likely out of freon. As for the performance from having the a/c on I'm not to sure about that. This is just my opinion and what I learned from other techs. Hopefully it's nothing to serious.