So today i was driving my car and i heard the ac pump cycling like crazy, it kicks on then in about 2 seconds shuts off, it keeps doing it and the fans come on the rpms change like they should, but it just wont stay on. My ac was always Ice Cold, to this day it was ice cold, i checked the pressure with a set of gauges, its all fine and dandy, seems like a electrical issue, Any feedback on this would be great.

Thanks, Professor`

 

I would start with the low pressure switch if you are sure your refrigerant pressure is ok.

 

Hmm that sounds about right , but after the car sat for awhile and when i went back out, it worked fine. i dont get it. its Random

 

I think the ECM calls it the refrigerant pressure sensor. I'm thinking if this is faulty, it will be telling your compressor to kick on when it does not need to.

Did you actually hook up a manifold pressure test set, and not one of those cheap autostore gauges?

 

Yeah i have a manifold set.
After the car cooled off it now works fine.
Can a failing thermostat cause that ?

 

I would check out that plug near your right strut tower , by wiggling and checking the pin condition( no corrosion). I would also check those grounding points around that area for their condition also.....

 

AC clutches are very sensitive to voltage, and will act like this. It could be a sign a charging system or ground issue. Might not be a bad idea to have charging system check done before you have any major work done. Some shops will replace the compressor/clutch without even thinking about a voltage issue & the problem will come right back.

 

A bad thermostat would cause overheating and if the engine temp sensor reaches a certain temp, it will shut the AC off.

 

Hmm i did recently remove the ac compressor to replace the alternator, only 4 bolts and push it to the side, no biggy, but no issues before i removed it also, i wonder if its a bad ground, but the bolts are torqued to spec and it wasent really dirty

 

Iam not sure what it is, it was working fine again and today it started doing the same thing., i cant figure it out.

 

So, when you moved the compressor, did you disconnect the lines?

 

Nope not at all.

 

So today i disconnected the pressure switch and used a jumper to see if that was the issue, it worked for abit but as i was driving the ac pump would make a whirring sound and got much louder with acceleration, the air stayed nice and cold and then even with the jumper it kicked off.....removed the jumper and just left it open and it came back on for abit with no connection to the pressure switch....... either the clutch in the pump is going or something i cant fathom is amiss......

 

Have you had a complete charging system check done yet? If you replaced the alt, you had/have an issue. There could be other problems ie. corroded battery cable (where you cannot see), low battery voltage. Like I said before, the AC clutches are very sensitive to voltage and the problems you are discribing are a classic symptom.

 

To much air in the system, that is the issue, it just needed drained and refilled.

 

Mine has been doing pretty much the same as yours did lately. I have also noticed on mine that the AC seems to work if the outside temp is 75 degrees or cooler (evenings and mornings) but if it is much warmer than that it cycles on and off for a couple of seconds or so. I had the freon level checked and it was fine. I wonder if I emptied it and re-filled it if it would help mine too? How much freon do these hold if empty? Thanks!

 

I am thinking about trying the purge/refill but I am the original owner and I know that my AC has never been serviced so I am trying to figure out how mine could have air in the system? Any ideas?

 

If you are going to do the refill by yourself, do it incrementally i.e. only add 1/3 of a can and test it for couple days. If it gets cold enough, STOP adding any more. If you add little more, it will become WORSE.

- Vikas

 

I recently read that all AC systems can have a small leak. Apparently the EPA (or whoever measures these things) allows up to 10% discharge per year. Have you checked the low pressure? I recently checked mine and found that I was in the low 30's PSI. The AC was working okay but I had some left over from refilling my wife's Sienna so I used up the remaining tank. Brought me up to around 36 PSI.

Hope this helps.