A/C cycling too much

I have a 96 and recently I noticed my a/c isn't cooling. When I turn on the A/C, I can see the compressor start, but it cyles off in about 5 seconds. Then it cycle's on again. Would it be some sort of swich issue, or if the coolant is low would it act this way?

Thanks

Your need to recharge the system. But first you must check to see if there is a leak, such as a seal in the compressor, or in a fitting somewhere.

You can buy a Recharge & Measuring Kit for about $20.00, and with it, you will need to buys several cans.. of R-134a. Just read the instructions, and you can do it.

I also have a '96 Tahoe and recharge mine every years.

I put on a pressure gauge, and it indicated the pressure was pretty good. Tried to add a little freon, but I don't think much gets in due to the cycling. Any other ideas?

If you are going to do it do it right.
Get a recharging gauge set on it and check the high and low side both.
Check at idle then at 1500 rpm and post back pressure readings.
Or go to this link for more info on it.
http://www.autoacforum.com/
MT

If the presure is correct, then the clutch cycle switch has gone bad.

Pressures alone will not tell you how much freon is in system, it will only tell you if compressor is operating/cycling. An empty 30lb tank will read same pressure as a full 30lb tank if hooked up to manifold set. Only way to know how much freon is in system is to take it out/weigh it. What I would do is evac remaining freon, pull vacuum on system (27hg for 30mins) then recharge to proper amount, may want to add a little oil ---that way you definitely KNOW how much freon is in system...

Kevtech
Welcome to your first post on AF
True the air cond low and high side reading will not tell you the charge down to the oz.
But a good air cond tech with a good set of gauges can tell if the system is low or over charged from the gauge readings.
Also the pressure reading in a operating air cond system is a lot different than a empty gug of freon. If the jug is empty it will have no pressure in it.:lol:
Freon developes its pressure from the tempture it is at.
Also freon in a air cond does not get cold it only removes the heat from the evaporator and puts it out the condenser.:lol:
MT

Kevtech
Welcome to your first post on AF
True the air cond low and high side reading will not tell you the charge down to the oz.
But a good air cond tech with a good set of gauges can tell if the system is low or over charged from the gauge readings.
Also the pressure reading in a operating air cond system is a lot different than a empty gug of freon. If the jug is empty it will have no pressure in it.:lol:
Freon developes its pressure from the tempture it is at.
Also freon in a air cond does not get cold it only removes the heat from the evaporator and puts it out the condenser.:lol:
MT
Hook up a gauge set to an empty tank, then to a full one---you will see, the pressures will be the same. Try it, you will be surprised....

You might think it is empty but if it has pressure in it it still has vapor or liquid freon in it.
No way a empty tank can have freon pressure :grinyes: :lol:
MT

mt is right, a running ac system is not the same as a static pressure reading. static pressure readings from an ac system can only tell you if there is or isnt refrigerant in the system though. you can tell a lot from a loaded ac pressure readings, one of which how full or empty the system is.

Try It.

TRY WHAT TRY WHAT

Hook up a gauge set to an empty tank, then to a full one---you will see, the pressures will be the same.

Aw Man why would I want to do a thing like that.
If a air cond system is empty it will have no pressure.
If a freon jug is empty it will have no pressure.
If a gas tank is empty it will have no gas in it.
If you find a freon jug that has pressure it it has freon in it or someone slipped air pressure in it.
But that all has nothing to do with checking a air cond for the proper freon charge.
I fail to see where it is relevant to the situation so it is not in my best interest to go around and testing/resetting the pressure on empty freon jugs which have no pressure to start with.
MT

I stand by what I state, a manifold gauge set will NOT tell you if the correct amount of freon is in the system. an "empty" freon tank will still have residual freon in it, therefore, it will show pressure reading on gauge, I qoute: "Freon developes its pressure from the tempture it is at". ---does not matter how much freon is there, ambient temperature will make the pressures the same in both an empty tank and a full tank. ex: 70 degrees = approx 70 psi., full tank or not. It is damn near impossible to charge a system to the correct level using a gauge set only. I do agree, "If you are going to do it. Do it right the first time."

kev ive charged systems for years using gauges only with absolutely no complaints. the trick is to know what youre doing. going by pressure, inside temperature and experience you can do a lot. an empty refrigerant jug is empty, 0 pressure. if it has pressure its not empty. the problem with a lot of mechanics these days is that they rely on machines to tell them everything. you cant get a car in with an ac cycling problem, hook it up to a machine have the machine suck it down and refill it and expect it to be fixed every time. you have to hook gauges up to it and see what its doing.

I am not saying that it is not possible. I too have evac/recharged many myself using only a manifold... I know there are many other things that can cause a compressor to cycle too fast, besides being low in charge. Just making the point of the traits of freon. If there is residual freon in an empty tank, you will get a pressure reading. It will read the same as a full tank. Try it. I did not believe it either until my instructor did it in front of me. Outside temperature will make even the smallest amount of freon expand (boil), but it will only expand as far as the tank will allow, thus creating pressure.

I am not saying that it is not possible. I too have evac/recharged many myself using only a manifold... I know there are many other things that can cause a compressor to cycle too fast, besides being low in charge. Just making the point of the traits of freon. If there is residual freon in an empty tank, you will get a pressure reading. It will read the same as a full tank. Try it. I did not believe it either until my instructor did it in front of me. Outside temperature will make even the smallest amount of freon expand (boil), but it will only expand as far as the tank will allow, thus creating pressure.
Kevtech.
Your instructor is playing with your brain. He is saying the tank is empty but then says it has residues of freon. An empty tank is empty. No residues of freon or anything in it. It will have no pressure if it is empty. But if it is not empty and has residue of or freon in it it will have pressure close to the air temperature surrounding it.
Also a car air cond system will have pressure close to the air temperature on high and low side if the system is not running.
But that is not relevant to the case of a cycling pressure switch.
Also if you want to get technical evacuating a system at 27 in of vacuum for 30 minutes and adding a little oil is not the correct procedure to evacuate a system or to add oil.
Here is a lot of good accurate info on air cond system recharging.
http://www.autoacforum.com/
It is true a set of aircond gauges will not tell you the freon charge down to the oz.
But they will tell you if an air cond system is working right and if it is working right it has real close to the right amount of freon in it.
Why do you thing they put gauges on a recharging gauge set?
They put them on there so a person can see if a air cond system is working right and has the right amount of freon.
It you are doing air cond work the gauges and a recharging manifold is you best buddy.
All you have to do is learn how to use them.
http://www.autoacforum.com/
Again go to this site for the correct information and proper way to evucate and add/check oil and recharge air cond systems.
MT