Air Conditioning compressor cycles on and off S185

[skidsteer.ca]

I got a can of oil sucked into the system then I hook into the low side port to add some r134a, but the compressor will only stay on for 2 or 3 seconds now.
Guage shows @ 45 psi when it is off and drop quicky to @30 but then the compressor cycles off.
Any ideas why it cycles so fast and why it won't stay on?
Skidsteer.ca

 

[OldMachinist]

Low pressure switch is turning it off when it get down to 30. If the system was real low on freon you'll need to put a jumper wire in the low pressure switch connector to get the compressor to run enough to add freon. The switch is on the reciever/drier. Just take the connector off, make a jumper out of a paper clip and put it in the connector.

 

[skidsteer.ca]

Low pressure switch is turning it off when it get down to 30. If the system was real low on freon you'll need to put a jumper wire in the low pressure switch connector to get the compressor to run enough to add freon. The switch is on the reciever/drier. Just take the connector off, make a jumper out of a paper clip and put it in the connector.

That was my thinking too after I posted and I did just that.
The compressor ran longer, but still only 10 secconds then it blew off the safety valve for a seconds and I removed the jumper.
So I bled off some into a empty 12 oz can and moved it to another vehicle, 3 times.
Now the initial run is @ 2 mins then it begines to cycle every 30 seconds or so.
I'm thinking it is the hi limit switch interupting the power, strangly though the low side pressure is @ 30
My hose does not connect to the high side so I have no reading there.
It had been cooling ok but yesterday was the first 80 degree day we had so I conected to the low side and though I'd top it up. Maybe I should have left well enough alone.
Btw my guages seems to read normal on other vehicles. In fact I have 2 and they both agree.
Could not be there is a circulating issue could there?

 

[willie59]

That was my thinking too after I posted and I did just that.
The compressor ran longer, but still only 10 secconds then it blew off the safety valve for a seconds and I removed the jumper.
So I bled off some into a empty 12 oz can and moved it to another vehicle, 3 times.
Now the initial run is @ 2 mins then it begines to cycle every 30 seconds or so.
I'm thinking it is the hi limit switch interupting the power, strangly though the low side pressure is @ 30
My hose does not connect to the high side so I have no reading there.
It had been cooling ok but yesterday was the first 80 degree day we had so I conected to the low side and though I'd top it up. Maybe I should have left well enough alone.
Btw my guages seems to read normal on other vehicles. In fact I have 2 and they both agree.
Could not be there is a circulating issue could there?

Every Bobcat that I've worked on has a sight glass on the filter/dryer so you can tell if it needs additional R134A. You really should get the materials you need to connect to the high side of system. Kinda hard to know exactly what's going on without that tidbit of info.

 

[skidsteer.ca]

Every Bobcat that I've worked on has a sight glass on the filter/dryer so you can tell if it needs additional R134A. You really should get the materials you need to connect to the high side of system. Kinda hard to know exactly what's going on without that tidbit of info.

Yes I need to purchase a good guage set. It was low on the low side so I gave it a oil charge and then freon and I think the oil is where I went wrong. According to the service manual haveing too much can cause the the high side pressure to get to high.

 

[willie59]

Yes I need to purchase a good guage set. It was low on the low side so I gave it a oil charge and then freon and I think the oil is where I went wrong. According to the service manual haveing too much can cause the the high side pressure to get to high.

Well, 30 psi is not unusually low for the low side. After all, that is the "suction side" when compressor is operating. The low side may vary from roughly 10 to 40 psi when system is operating and depending on temperature conditions. What may be kicking your system off is high side pressure too high, a faulty high pressure switch, a faulty temperature switch on the evaporator, or even a externally clogged evaporator which will confuse the hell out of the temperature switch. Being able to monitor high side pressure is a key piece of info. If it turns out that you have too much oil in the system, you may have to do an evacuation, fit a new filter/drier, and start over again. Hope you have some luck with it, summer is here.

 

[skidsteer.ca]

Well, 30 psi is not unusually low for the low side. After all, that is the "suction side" when compressor is operating. The low side may vary from roughly 10 to 40 psi when system is operating and depending on temperature conditions. What may be kicking your system off is high side pressure too high, a faulty high pressure switch, a faulty temperature switch on the evaporator, or even a externally clogged evaporator which will confuse the hell out of the temperature switch. Being able to monitor high side pressure is a key piece of info. If it turns out that you have too much oil in the system, you may have to do an evacuation, fit a new filter/drier, and start over again. Hope you have some luck with it, summer is here.

The system is clean externally and makes works ok for the first 5 minutes, then the compressor begins to cycle. At idle rpm the cycles are longer, rev it up they get shorter but the longer it runs. So if a person over oiled it it would be best to fit a new filter drier too then? I guess its hard on those?
One thing we have not had much summer here, barely 60 f today, but I would have used it Saturday one of the few 85 degee days we have seen yet and and very humid.
I' have to talk to my friendly Bobcat dealer, I'm asuming a drier is oem only?
Thanks
Ken

 

[skidsteer.ca]

The system is clean externally and makes works ok for the first 5 minutes, then the compressor begins to cycle. At idle rpm the cycles are longer, rev it up they get shorter but the longer it runs. So if a person over oiled it it would be best to fit a new filter drier too then? I guess its hard on those?
One thing we have not had much summer here, barely 60 f today, but I would have used it Saturday one of the few 85 degee days we have seen yet and and very humid.
I' have to talk to my friendly Bobcat dealer, I'm asuming a drier is oem only?
Thanks
Ken

Well hooked up the new guages and it was approaching 400 psi on the hi side after it had run a few minutes. Low side it @ 15. So I took it into town and and had them recover some from the high side, reducing the pressure to 300. Still a bit over the 265 in the manual, The compressor now runs stead and it is good and cold even though it is a bit lowon pressure on the low side.
Ken

 

[Jyuma]

Well hooked up the new guages and it was approaching 400 psi on the hi side after it had run a few minutes. Low side it @ 15. So I took it into town and and had them recover some from the high side, reducing the pressure to 300. Still a bit over the 265 in the manual, The compressor now runs stead and it is good and cold even though it is a bit lowon pressure on the low side.
Ken

Holy crap... you guys have A/C in your machines for the summer? What next... heat in the winter?

I have no door and a wire mesh cage. Winter and summer are a real challenge. Spring and fall are a pleasure.

 

[skidsteer.ca]

Holy crap... you guys have A/C in your machines for the summer? What next... heat in the winter?
I have no door and a wire mesh cage. Winter and summer are a real challenge. Spring and fall are a pleasure.

Its been in the +35C range here all week with humidex in the 40's. We are shutdown on the bush operations so I did a little road job yesterday.
It would have never yesterday happened without AC. I think I'm spoiled forever.