A/C experts - 5088 IH

[searcyfarms]

symptom - ran fine at idle - low pressure was 35 would drop to about 30 then back up to 35 - high pressure was running around 250 with a fluttering gauge

using mac tools gauges for R134a, system was converted to R134a before i purchased it.

I was only getting around 70 degree air out of it so i increased engine speed from 800 up to about 1350 -

i noticed my thermometer going up instead of down

went out and looked at gauges and low side at 90 and high side about 100 so the system has equalized in pressure - does that sound like a stuck expansion valve?

its been sitting about 2 hours and the pressure has not dropped at all on either gauge.

The compressor will not kick on - presumably because of the high low side pressure.


FYI - it still has the old YORK compressor on it. I did remove the top of the cab today and cleaned out everything up there with air, wasnt much really up there, cleaned out inside cab filter as well as cab filter. System had to be charged last year and got me through the season, refrigerant light came on this spring and we havent used or messed with it since. The low pressure light was not coming on today when i attempted repairs so maybe bulb burned out?

I do not have a way of evacuating the system or i would do that and start over to get the pressures off.

I am in missouri, tractor was running in open building with outside temps of low 90s and around 80% humidity.

Thoughts? Ideas?

THanks in advance, Robert

 

[TractorGuy]

Locate the low pressure switch and jump it to start the compressor and get running readings. Pressures will tend to equalize when the compressor is not running. It may just be low on freon. Could also be a loose wire or bad low pressure switch. Should find it on the drier with two wires connected to it. Make sure the radiator and condenser are clean. Wash them out good with water from the engine side.

If you were getting those readings with the compressor running it would indicate a bad compressor.

 

[searcyfarms]

there are a couple of substantial orange looking electrical wires coming off the side of the top of teh compressor is there anything that might help me find the low pressure switch? like inline electrically with the wire that goes up under the clutch? or something of that nature?

 

[jaxs]

Locate the low pressure switch and jump it to start the compressor and get running readings. Pressures will tend to equalize when the compressor is not running. It may just be low on freon. Could also be a loose wire or bad low pressure switch. Should find it on the drier with two wires connected to it. Make sure the radiator and condenser are clean. Wash them out good with water from the engine side.

If you were getting those readings with the compressor running it would indicate a bad compressor.

That ^^^ is good advice.

there are a couple of substantial orange looking electrical wires coming off the side of the top of teh compressor is there anything that might help me find the low pressure switch? like inline electrically with the wire that goes up under the clutch? or something of that nature?

The low pressure switch referenced by TractorGuy is mounted on low pressure line,has 2 wires (1in & 1 out) and shouldn't be far from compressor. One wire on compressor (clutch to be exact) usually run's a short distance to chassis ground. The other wire will run to low pressure switch,follow it. Forget about evacuating,there's no need as long as system never reaches 0 psi. It's v-e-r-y important you understand and follow guage hose purging proceedure when hooking guages up. Otherwise moisture and air are introduced and really screw's things up.

 

[TractorGuy]

Actually the first test is to verify you have or don't have power and ground to the compressor clutch.

Location for the low pressure switch may vary but it is usually on the receiver drier. The drier may be located anywhere but a common location would be in front of the condenser which IS located in front of the radiator. Sometimes the switch can interrupt the power lead to the compressor or it may complete the ground to a relay. If you can follow the positive lead from the compressor clutch and it plugs into a relay then the low pressure switch most likely interrupts/completes the ground to the relay. Heavy wire leads going to the compressor may indicate it powers direct without a relay.

Understand I am not suggesting you bypass the low pressure switch and leave it that way. It's purpose is to protect the compressor from running with a low refrigerant charge. This is only to get a compressor on gauge reading. You could also run a heavy jumper from battery positive to the clutch positive wire on the compressor if it isn't hot already.

If the low side reading is much below 20 PSI with the compressor running it will probably be due to a low charge. Just add a can and see if it lasts a while. Be careful not to overcharge the system. If the high side starts to go north of 250 you are getting too much head pressure for most systems.

I'm not familiar with your specific tractor and I don't have access to a manual for it so I can only speak in possible configurations.

 

[searcyfarms]

i gave up on it today, i bought it 2 yrs ago knowing it had AC issues and had it charged the first yr and it made it thru the summer but it was not GREAT cool air, yes everything was all cleaned out etc....

I could not get it to fire power to the compressor and i found the low pressure switch but i did not have power to the low pressure switch to even get to the compressor so something is not right, I did not have a wiring diagram and i took the roof off the cab and looked around for things but didnt see any wires off or fuses blowing and i could hear the thermostat clicking also on the knob you turn it.

I applied power to the compressor and it ran find, pulled the pressures into a descent range of 25 to 30 on the low side and 250ish on the high side

this is an expansion valve system not an orifice type

the compressor would only cool down to about 70degrees which i know last year was only getting around 68 so its seemingly similiar but in a hot tractor cab that doesnt do well to keep you cool if that is all teh cooler air it can put out.

Anyway, I have contacted our local repairman who works on them and asked him to order new lines ( the old ones were not replaced when it was converted to R134a ) and replace the old york compressor with a sanden along with whatever else it needs.

Dad is 80 and wont be able to run the tractor too many more years and with his diabetes he has to be pretty careful. I want him to be comfortable and go as long as he can.

Got a new REI modern radio installed and working in it for him this weekend as well as door seals glued in. He should be all set once we get the A/C finished up.

thanks for helping I think this should get all the kinks out and quit having to mess with it.

 

[TractorGuy]

Did you try just connecting the two wires together at the low pressure switch? Like I said they may just complete the ground to a relay. It doesn't necessarily have power on those wires. You really need to try to find a wiring schematic for it if you can't trace all the wires. It could also have a bad relay or connection at a relay.

Not sure if this is relevant to your tractor or not but it was the first image that came up when I searched for a diagram for you.
http://cdn.compknowhow.com/carterandgruenewald/wiring_diagrams/86series6.jpg

Sounds like it has an adequate charge so if connecting the two wires together at the low pressure switch made it work then that switch is bad. IF that switch was bad you would have to evacuate the system to replace it.

It may or may not do any better with the Sandin compressor but at least it was made to use with 134A.

For the sake of emphasis and repeating myself, MAKE SURE ALL THE DIRT IS CLEANED OUT OF THE CONDENSER AND RADIATOR!

Cabs are glass ovens, AC can only do so much. You might also add some tint or even a couple of pull down shades will help. I added a couple of the shades in my backhoe and it seems to make a difference. You can still see through the holes.

 

[skipmarcy]

If your system has a drier in the HIGH pressure line at the condenser it will not have a LOW pressure switch there - that would be a high pressure cut-out switch. A low pressure switch will be on the suction side of a system where you might possibly have an ACCUMULATOR drier instead of a high side drier. With R134a you need to charge the system strictly by system capacity too and hope that someone hasn't added additional oil to the system which takes-up some of that capacity. An R134a system can lose a lot of efficiency with just a couple ounces over or under charge. Really should have a working knowledge to service refrigerant systems before trying to service them ...

 

[searcyfarms]

Cabs are glass ovens, AC can only do so much. You might also add some tint or even a couple of pull down shades will help. I added a couple of the shades in my backhoe and it seems to make a difference. You can still see through the holes.[/QUOTE]

I have been looking at those pull down type, where did you get yours ?

 

[searcyfarms]

regarding bypassing the low pressure switch, i didnt do that i guess i could have but after examining the cracks in the lines that are 37 yrs old, and seeing dad stressing in the heat then end up with low blood sugar not to mention we were working inside the shop in the shade with a breeze and fan blowing, i thot id rather fix it right than try to rely on a system that old - our local repairman ( that most all use in our area ) is very good on these tractors/years - he has them of his own also - he will guarantee the system once he puts on new lines/orings/compressor and fixes it right, our other neighbor had him do his 886 two years ago and is more than pleased - 70degree temps out of a system are not acceptable that wont keep up