AC Cycling - how often is normal

[88GMCBurb]

I noticed a bit of oil leaking at the front of the AC compressor, not much - just enough to notice that it splattered on the inner fender a bit and a thin residue. Not actually dripping to the ground or anything. But I assume there is some leakage of refrigerant.

Now, I notice that compressor is cycling on for about 10 to 15 seconds and then off for about 15 to 20 seconds. This is with temperature outside of about 50 to 55 degrees idling in park.

System was converted to R134 about 6 years/40K miles ago with a new compressor.

Is this cycling about right or is it too often ?

 

[chevyuser74]

is your a/c cold when its hot out? but if theres oil leaking refigerant is also leaking which will cause poor ac performance and excess cycling

 

[imiceman44]

I noticed a bit of oil leaking at the front of the AC compressor, not much - just enough to notice that it splattered on the inner fender a bit and a thin residue. Not actually dripping to the ground or anything. But I assume there is some leakage of refrigerant.

Now, I notice that compressor is cycling on for about 10 to 15 seconds and then off for about 15 to 20 seconds. This is with temperature outside of about 50 to 55 degrees idling in park.

System was converted to R134 about 6 years/40K miles ago with a new compressor.

Is this cycling about right or is it too often ?

That is too much, it should stay longer both on and off.
A converted system will lose refrigerant quicker than a system originally R134, even with a new compressor, you still have the old porous hoses.
I am amazed it lasted 6 years.
If you have a leak now is the time to change hoses and seals.

 

[4X4HIGH]

I noticed a bit of oil leaking at the front of the AC compressor, not much - just enough to notice that it splattered on the inner fender a bit and a thin residue. Not actually dripping to the ground or anything. But I assume there is some leakage of refrigerant.

Now, I notice that compressor is cycling on for about 10 to 15 seconds and then off for about 15 to 20 seconds. This is with temperature outside of about 50 to 55 degrees idling in park.

System was converted to R134 about 6 years/40K miles ago with a new compressor.

Is this cycling about right or is it too often ?

Maybe you've overlooked this but do you have the defrost on when this is happening? On AC equipped vehicles when the defrost is on it cycles the AC compressor just like you've described.

Also, when there is a leak in the system and the system reaches a certain point there is a low pressure cut off switch that won't even allow the compressor to turn on at all.

 

[throttleissues]

88GMC, just wait for the weather to warm up and see if it works. Any input about the cycle times are just going to be guesses, especially when it's not really hot out yet. The cycle times will change timing depending on how long the A/C has been running as well, since the refrigerant is not properly distributed at startup. The defrost function just turns on the A/C the same as any other use of the A/C, and the cycling is from the low pressure switch cutting out the comp. Pressures are just lower when it's colder.

 

[4X4HIGH]

88GMC, just wait for the weather to warm up and see if it works. Any input about the cycle times are just going to be guesses, especially when it's not really hot out yet. The cycle times will change timing depending on how long the A/C has been running as well, since the refrigerant is not properly distributed at startup. The defrost function just turns on the A/C the same as any other use of the A/C, and the cycling is from the low pressure switch cutting out the comp. Pressures are just lower when it's colder.

You are wrong. The AC compressor is cycled purposefully when the defrost is turned on and it is suppose to cycle on and off repeatedly.

 

[throttleissues]

You are wrong. The AC compressor is cycled purposefully when the defrost is turned on and it is suppose to cycle on and off repeatedly.

You still can't read worth a damn. That's why I just said that the defrost turns on the A/C, but you implied that it somehow turns it on differently so that Def won't cycle the same as when you turn on the A/C. Whether it's set to A/C or Def, the A/C compressor clutch is turned on and cycled by the pressure switch EXACTLY THE SAME WAY. And yes, they cycle purposely, since that's what the pressure switch does in an FOT A/C system, because they don't have an actual expansion valve to adjust to the pressures like the old systems did.

 

[4X4HIGH]

We obviously don't see eye to eye so i'm going to try not to reply to anymore post that you reply in just so we don't have any arguements. I will leave saying that the AC compressor does cycle differently when the defrost is on versus when the switch is in AC mode.

 

[throttleissues]

We obviously don't see eye to eye so i'm going to try not to reply to anymore post that you reply in just so we don't have any arguements. I will leave saying that the AC compressor does cycle differently when the defrost is on versus when the switch is in AC mode.

True, we don't. You can't seem to understand that the Def doesn't turn the A/C on any differently than turning on the A/C does. I can only explain this so many ways. I just don't want noobs reading this and thinking there are 2 different circuits to this, because there aren't.

 

[chevyuser74]

i repair a/c systems, i dont know everything, im not going to admit to such. but i dont believe the defrost cycles the a/c, i do know defrost turns on the a/c circuit though. i think the ambient temperature and the amount of refigerant in the system are the major factors in why the a/c cycles. this is my opinion by no means fact.

 

[chevyuser74]

im still gonna have to stay what i said in my first post, id wait till u can determine if the a/c is cold or not to jump to any conclusions

 

[throttleissues]

im still gonna have to stay what i said in my first post, id wait till u can determine if the a/c is cold or not to jump to any conclusions

I would agree with that completely! I think we both mentioned that already, but it doesn't hurt to reiterate.

 

[Blue85]

the AC compressor does cycle differently when the defrost is on versus when the switch is in AC mode.

I am interested to know more about the provisions for this. TBI only, maybe? I know mine didn't come with any thing to accomplish that. I think what you say is true on newer vehicles, though.

 

[Blue85]

System was converted to R134 about 6 years/40K miles ago with a new compressor.

You are very fortunate that it turns on after not being recharged for 6 years. Whoever did the conversion must have done a good job. If the leak is new, soon it won't cycle at all anymore. If the leak is really small, you will just need a little refrigerant (and oil) and it will work all summer.

 

[kaharshs]

I may be over looking something, but have you just tried hooking up a set of r134 gauges to the system and reading the high/low side pressures? If you dont do a/c that often buy a cheap set. On the internet you will find a chart that will tell you the proper pressure you should be getting for the ambient air temperature. I used to do alot of a/c work in arizona when i worked at discount cab company and if the compressor is leaking fluid you are most likely gonna have a low system pressure. If the pressures are correct and its blowing cold leave it, high system cycling with odd pressure could mean a plug some where in ther system such as the orifice tube which on crown vics i worked on had a build in screen which would catch random ****e. Make sure condensor is clean and free of bugs and dirt. Make sure no kinks in any lines. If you think the pressure switch is bad i believe you have to drain the system because it screws directly in the line. If only low on 134 just top it off with some auto part cheapie and see how long it holds, might be more cost effective.

If you Choose going the whole 9 yard Go have your system drained if you want to replace the pump, replace the seals on the front of the pump is possible if not just replace with a rebuild one. Before re installing the pump pull out the old drier, orfice tube, and pressure switch. Clean the lines out, replace all o-rings, put on new drier, put in new orifice tube/screen, and new pressure switch. Then hook your pump up and pour in the correct amount of oil. Pressurized the system with some plain old air, hook your gauges up and make sure the pressure doesnt drop,if its good after 15 minutes continue with vacuum. If dropst spray your system with soapy water and look for the leak, the repair. Suck a vacuum for a half hour or so to remove any moisture from the system. Put in 134, dont put liquid in the low side it will blow your pump up. I hook up the bottle to the guages and turn the a/c on high and add refrigerant slowly till the pressure is correct in the system. You add by weight of bottle too but i dont. To check if its blowing cold inside rol up the windows put a meat thermometer in the vent and lets if set for a couple minutes cooling down.

Im sure I left out something, told a fib,miss typed and Im tired of typing

kyle