AC cold then compressor short cycles

[Xplorinator]

Replaced all AC components. Filled with R134A. From a cold start AC works fine. Once the system is shut off, the compressor goes into short cycling mode. Let the vehicle cool down for 30 minutes AC works fine. Shut the AC or the vehicle off and the compressor goes into short cycling and air not getting cold. Any suggestions?

 

[koda2000]

Replaced all AC components. Filled with R134A. From a cold start AC works fine. Once the system is shut off, the compressor goes into short cycling mode. Let the vehicle cool down for 30 minutes AC works fine. Shut the AC or the vehicle off and the compressor goes into short cycling and air not getting cold. Any suggestions?

When you say "A/C is shut off" what HVAC settings are you on?

 

[Xplorinator]

When you say "A/C is shut off" what HVAC settings are you on?

What I mean is, when I turn the AC off after the cold start, then turn it back on at any time it won't blow cold air.

 

[Viverette]

Are you having to recharge the system to get it back to blowing cold after it short cycles?

And just for double clarification, by short cycles, are you having the compressor click abiut 2 to 5 seconds on and then 2 to 5 seconds off?

 

[Xplorinator]

After filling the system with R134A the low side pressure stays at about 40 lbs when I start the car from cold, and the vent temperature is about 40 degrees below ambient temp. It will stay that way as long as I don't turn off the AC or car. Once I do turn off the car or AC, then turn the car and the AC back on, the compressor goes into the short cycle of about 4 to 7 seconds; the low side pressure drops to about 25 lbs and the low side pressure switch disengages the compressor- the pressure goes up to about 60 and the compressor reengages, starting the short compressor cycle, and the vent temperature is about 5 to 10 degrees below ambient temperature.

 

[Viverette]

+1 for details.

One question, does it do it immediately after stopping and restarting the vehicle or after it's been sitting after the first initial recharge?

Either way, to me, it sounds like a leak. Especially with the dropping of pressure and inability to maintain a constant pressure as well.

I'm currently having a similar problem with mine.
I finally discovered a leak coming from the evap core. Mine lasts about a day and a half before it goes to short cycles and no cold air. It could be the same problem but it could also be something else.
Evap core is just in the back of the engine bay of the passenger side against the firewall, right in front of the accumulator and beside the blower.

Have you tried using a sniffer or know someone with access to one ? It can help diagnose if there is a leak in the system, especially if it can't be visually seen.

Also, check your lines going to the compressor and make sure there aren't any leaks around the o-rings.

I hope this helps in some way

 

[96EXXLTinCO]

I didn't see any mention of it, but when you say you replaced all AC components, I assume this means you had the system open? If so, you did pull the system down into a vacuum before refilling?

 

[david4451]

I have same problem and no leaks.
This may help if you disconnected battery hand book says to start car till at operating temp then switch ac on for short time the go for 20 minute drive so computer relearns settings.
My ac function did improve, but at idle will sometime cut on and off, if I rev engine to 1000 rpm ac comes on and stays on but it will sometimes cut in and out at idle.
Does your ac cut in and out at higher rpm?

 

[Xplorinator]

For now its holding pressure, and there are no leaks in the system. When filling the system I also used a UV dye.

I didn't see any mention of it, but when you say you replaced all AC components, I assume this means you had the system open? If so, you did pull the system down into a vacuum before refilling?

There's the million dollar question! No I did not and I ran out of money before I could get the vacuum pump. It's $20 at Harbor Freight, and than there is 2 more cans of Freon. David4451 brought up a good point that the computer has to relearn over time. It does seem to be working more often then not and the vent temp averages about 30 degrees below ambient temperature. I was afraid I had installed the wrong orifice tube because there are three different kinds. I won't know until the beginning of next month if vacuuming the system will solve the problem. At least I have AC sometimes.