For the past few months, my AC has been acting up. Most of the time it blows cold air. Maybe once or twice a week (note, my gf and I drive the car a lot) it either starts off blowing cold air, then starts getting warm and stays warm, or it just starts blowing warm air.

We noticed that the problem usually occurs when the car is idling or moving at a slow speed (under 20mph). When this happens, we can hear a “knock” or “click” sound coming from under the hood with short intervals of a few seconds in between (we’re thinking this sound is the sound of the radiator fan turning on and off because we watched the process occur a few times in our garage). When we hear the sound, the radiator fans turn on, a few seconds later it makes the sound and the fans turn off, a few seconds later we hear the sound and the fans turn on again, etc, etc, etc…..you get the picture. Every now and then, we also hear a high pitched sound to go along with the “knock” or “click” that doesn’t stop unless we turn the AC off.

I’m no mechanic or anything and don’t know too much about cars besides the basics. We don’t want to spend a whole lot of money to correct the problem if it’s not necessary. I’d rather do it ourselves if it’s not a complicated process. I’ve done a couple DIY’s with my good friend, but we don’t have much experience.

We re-charged the AC about 8 months or so ago. Could it mean that it needs another charge? Or is there something wrong with the AC system itself? We’re clueless. Any assistance or guidance would be appreciated.
I tried to be as detailed as I could, but if you need anymore descriptions or whatever, let me know. Thanks guys!

 

that squeel noise you hear leads me to believe that you've got a loose belt running the a/c pump, or a bad belt for that matter, at the most you should only have about a 1/2" in either direction (up or down from it's stock resting point) on the belt, more? tighten it, also, make sure it isn't really hard or shiney looking or cracked - any of those three problems? replace it. that's where I would start

 

The clicking you are hearing is either the a/c compressor cycling which means low freon charge. But It sounds to me more like the low speed electric fan may need replacing. Its not keeping up with the demand at slow speeds when there is not much air flowing over your heat exchnger which is usually mounted just behind the radiator. The fan kicks in to help move air during idle. I had to replace one once on a 4 cyl GM olds once. It was easy and fixed the problem. You shouldn't need to recharge your freon unless its leaking. Be careful you can over charge the freonand thenit will not cool properly.

 

Thanks for the input guys!

Sir Nasty, I'll probably take a look at your theory either tomorrow or over the weekend.

Roadking, if we overcharged the AC, how are we able to tell? My friend has that guage you plug in. When we re-charged the AC, we used the same guage and made sure the pressure was within the correct range or whatever you call it.

 

If you already recharged the system once before, that would lead a person to understand the system has a leak somewhere. If you didn't add flourescent dye, you'll have to start looking for oily spots where the freon is leaking out.
Also take the electrical connector off of the pressure switch and look in there, common place. Next time you have the system serviced be sure to recharge the oil andI strongly recommend using Flourescent dye.
Your description sounds like the A/C is short cycling due to low charge.
that 'Click' you hearis probably the electric clutch of the compressor turning on and off.

 

Hondadude, forgive my ignorance, but I'm able to get the flourscent dye at an auto part store?

What is the electrical connector/pressure switch & where is it located?

So, if my AC unit is leaking, do I have to have someone fix it for me?

 

what are you talking about ?? low speed electric fan ?? heat exchanger ??

I am with the guys that suggest that the clicking noise is the compressor clutch cycling , when it cycles it also turns the fans on and off ,,, a more frequent than normal cycling could be the thermostatic switch acting up which is located inside the evaporator ,, not reading the temo properly at the eval , which in turns it grounds and turns a/c on,, I have seen them where they at times click 5-6 times in a row real fast ...

like other suggested, since the a\c works at times you might chk the pressures make sure that system is not low on freon,, if it is , since you had the system charged . there might be a leak ,, you might have to put more freon to top if off and some dye to properly locate the leak,,,, As for the high pitch sound. make sure that the belt is adjusted properly , if it is,, noise might be coming from compressor or 1 of the fans ,,both fans run when a/c is on and turn off as soon as you turn a/c off,, than they will come on just when needed to keep engine from overheating wether a/c is on or off

 

Ok, I'll probably try out DesertHonda's advice and go from there. Hopefully I'll have time this weekend. Busy weekend with the Super Bowl and all. I'll let you guys know what happens if I get to......