A/C compressor kicks in and out

[Tractor Seabee]

In general AC/refrigeration is not a DIY enterprise. You are not going to learn in one episode the technical expertise it takes a mechanic 6 months of school and years of experience to learn. It is one thing to put gauges on and a whole different thing to understand the information. A set of pressures can mean more that one thing could be wrong. Low suction pressure for example could mean low refrigerant but could also mean several other things could be wrong. Good technicians use pressures, temperatures, feel, hearing, and solid thermodynamics theory to arrive at a proper diagnosis. That is why the get the big bucks.

Ron

 

[number two]

Everybody brings good points to the table.
Is the A/C blowing cold or not even though the compressor clutch is cycling?
If it is blowing cold,most likely there is nothing wrong.
Should it not be cold,then the diagnosis begins.

We then need to know how the system works.
Maybe someone has a WSM for the RTV?

Many but not all AC systems cycle the compressor clutch.
The GM DA5 is a variable displacement compressor that runs constantly but changes swash plate angle to vary the the displacement-i.e. load.
This does away with the "jerk" the driver feels when the compressor kicks in.

My Kubota B3030HSDC cab model compressor clutch cycles but
the cycling is controlled by a temp sensor at the evaporator core as opposed to a pressure switch more often used,although temp and pressure are directly proportional.

In summation-please post back on your situation as a guage test may not be needed.
Perhaps simple electrical testing will suffice.
Good Luck!

 

[RickB]

IMHO to add refrigerant to AC system solely by looking at low pressure is a crap-shoot as there are too many variables other than low refrigerant. One needs to observe both low & high pressure gauges to correctly add refrigerant.

Couldn't agree more. Troubleshooting A/C problems without high and low side service gauges is like troubleshooting electrical problems without a VOM.

You can do it, but it's a lot like throwing darts. Some hit, many don't.

 

[Lefty7]

Thanks large for all the input on this.

Yeah, Tx Jim, she's a clean machine, and you're right - I don't wanna start shooting craps with r34. Since posting this, some of my own research is being echoed by comments by Wimac and dstig1: that, (unlike my old Dodge van), the on-and-off-again of the compressor is not necessarily wrong. And although I have only a single gauge for the low pressure side, it shows within spec, so it appears that it is NOT in need of refrigerant, and there is likely no leak. Why I can't see diddly in the sight glass is curious - but the A/C is cold. So I've decided to stop trying to fix things that ain't broke. (I got plenty of things that really need fixing.) Maybe if the outdoor temps get really freakin' hot, the compressor will stay on.

This poochie isn't my old van, and I shouldn't treat it the same way. Yeah, I hear ya, crazyal.

Thanks again. You guys are the best.

Have some fun. ~Lefty7

 

[C4Ranch]

I can't see diddly in my sight glass on my tractor but blows cold so I havent thought twice about it.

 

[dstig1]

but the A/C is cold. So I've decided to stop trying to fix things that ain't broke.

Then you have your answer: working correctly as is. Go worry about a real problem

Happy to help.

 

[Lefty7]

Gotcha.

But the whole thing that got me started was that in-and-out, on-and-off compressor business - which, if it was occurring on one of my other vehicles (that I'm more familiar with), would be a potential problem. If I can see them coming, I try to steer around them.

So: if that's the way it's supposed to be, if that's what it's like when it's working correctly, I'm cool with that. ~Lefty7

 

[meos1]

In general AC/refrigeration is not a DIY enterprise. You are not going to learn in one episode the technical expertise it takes a mechanic 6 months of school and years of experience to learn. It is one thing to put gauges on and a whole different thing to understand the information. A set of pressures can mean more that one thing could be wrong. Low suction pressure for example could mean low refrigerant but could also mean several other things could be wrong. Good technicians use pressures, temperatures, feel, hearing, and solid thermodynamics theory to arrive at a proper diagnosis. That is why the get the big bucks.



Ron

Same goes for computers with the exception of they need no pressure gauges unless they are super exotic. As a former AC tech the gauges do have a lot of information. If you can interpret them. You also need a card for pressure/temp conversion. I am happy to work on computers at $225/hour.

 

[dstig1]

Same goes for computers with the exception of they need no pressure gauges unless they are super exotic. As a former AC tech the gauges do have a lot of information. If you can interpret them. You also need a card for pressure/temp conversion. I am happy to work on computers at $225/hour.

OK, I'll poke the bear... I haven't found AC that hard to work on for the simple reason that the common problems are not hard to diagnose. Especially if you have a shop manual for the car on hand and a set of gages. You get the obvious - a leak/hole in something (rock punctured the condenser, corrosion, or a bad seal). These are easy to spot as there is typically quite a leak there! Next? The compressor is bad. Well, the rest of the system is pretty much passive, so it pretty much follows that the part that is going to go bad is the one moving part. Now of course the big question is if it screwed up the whole system and plugged the orifice... But put the gages on and see if the compressor is actually compressing or not... A bad sensor is another common one, but is also not too hard to spot or test for. Are there more complex issues beyond these? Of course there are, and they can get tricky, but this covers so many of the AC problems that it is worth trying it yourself, if you are handy. Just buy a set of gages before proceeding. They tell you a lot, if you think about it for a minute. And there are many internet sources that can point you in the right direction too.

No disrespect meant towards those trained in this, but like so many mechanical type problems, the common issues are really not that hard to deal with. You get beyond that, and yes it can get trickier and probably beyond the skills of many.

 

[RickB]

OK, I'll poke the bear... . Especially if you have a shop manual for the car on hand and a set of gages. Just buy a set of gages before proceeding. They tell you a lot, if you think about it for a minute. No disrespect meant towards those trained in this.

You didn't poke the bear, or disrespect anyone.

You just restated what many have said in this post. Gauges are a necessity to know exactly what is going on.