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Here’s a little hint that can help.

Almost all of the heat that is absorbed into the AC system on a farm tractor is picked up in the cab in the recirculated and fresh incoming air. Don’t try to cool the glass or the outer portions of the cab with the cold air outlets when it’s very hot out or when the engine is producing at high power levels. The only place that heat can be discharged from the freon loop after it’s absorbed is at the air cooled condenser out front which has its performance limits.

On a couple of my older machines with AC that was too unreliable, I put an electric fan off a car onto the condenser.
 

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Discussion Starter · #26 ·
I have changed many many coolant control valves on steigers, work sometimes and eventually the valve would just stick, usually open and you would only have heat. Replace the valve and good to go.
I’ve replaced that valve twice in the last couple years. I also checked the coolant lines to the cab yesterday and they are just Luke warm probably from the tractor heat.
 

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I ran through your posts pretty quick so I may have missed it but does your blower motor still run or does it shut off? Your pressures don’t seem unreasonable so I wouldn’t think your expansion valve is plugged. Did you pull the system down into a vacuum when you drained it?
 

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Discussion Starter · #29 · (Edited)
I ran through your posts pretty quick so I may have missed it but does your blower motor still run or does it shut off? Your pressures don’t seem unreasonable so I wouldn’t think your expansion valve is plugged. Did you pull the system down into a vacuum when you drained it?
Yes the blower still runs when the system shuts down and no I didn't evacuate the system before recharging it which according to the tech from the dealership I had out yesterday, might have been the problem. He explained that any air in the system could trigger sensors and the computer to shut the system down. He replaced the receiver dryer as well but didn't think it needed an expansion valve based on how the pressures were behaving. Also reflashed the relevant software. Sounds like there is a bit more to these AC systems than some of the older ones around the yard which just need a good sniff of freon and your good to go for the season.

I won't be running the tractor for a few days to see if the problem is solved but I'll post again once I know if its working properly. Quite often I see threads on here like this where members all pitch in with a big effort to find a solution to a problem but then the original poster never posts the outcome. A big thanks to everyone who contributed in finding a solution.
 

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Discussion Starter · #30 ·
So got out harrowing yesterday afternoon and the AC worked great for about the first hour then shut down same as before. Called the dealership and they suggested switching the fan and heat/cool switches around to test for a bad switch. Didn't help. Next item on the list I guess is the controller module to be changed. Unfortunately I can't just go pick one up and install it. Has to be programmed once installed I'm told. And the techs are all tied up with combines which understandably take priority. Going to be a hot afternoon.
 

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Discussion Starter · #35 · (Edited)
Kind of a strange deal going on with this tractor. Couple days ago I got wired the compressor and it built up to around 225 psi but no cold air. Today tech was out just as the AC shut down and when he activated the compressor it wouldn’t build pressure. Gave it a sniff of Freon and away it went for about 15 minutes. So today we installed new control module, relay which shuts down system if it freezes up, low pressure sensor for good measure and increased the fan speed. And I’m still riding around in my beach attire.
I wasn’t around when the tech worked on it the first time but I will definitely ask if they blew out any of the system.
They put in an Assist with Case to hopefully get some answers. Supposedly mine isn’t the only one of this vintage they are having issues with.
 

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The original HVAC control module was a proper ***** on the 600 that I drove for a lot of years. It had a lot of the same issues that were fixed just as you have done. I’m almost certain somewhere along the line that controller was changed out. The original one would go into an approximately 10 minute default to the last setting or else ventilation only if you made a bunch setting changes in just a few seconds.

Usually it would happen in the morning when the guy that checked it over for me started it and then began filling the drill, and had put it on maximum heat. I would get in and change all the settings and head down the line and that annoying SOB would just blow maximum heat for about 10 minutes. During the day if you only changed it a degree at a time per minute it likely would work all day. Try setting it how you think you will run it before you start the engine.

Sorry for your troubles. It gets expensive and there’s no guarantees on any of this stuff.
 

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This is kind of all over the place with the system building pressure and not cooling then the compressor not kicking in the next day. This is what I do on a poor cooling call hopefully one of these helps.

Check pressures if they are low I top the system and check for leaks. Once the leak is found I recover the system and repair the leak. I change the drier and if oil comes out of the lines the system is likely saturated with oil so it needs a flush. I unhook the lines from the compressor, remove the expansion valve and replace it with a gutted valve, and connect the lines that go to the drier with a hose bypassing the drier. I then back flush the system from the low side compressor hose catching the flush from the high side hose in a bucket. After two or three quarts of flush I blow air through the system. I do not add any oil back into the system. I then hook up the compressor, install a new expansion valve and new drier with new orings. I clean the evaporator (which could explain the working then quitting) under the seat as well as the condenser. I then charge the system and monitor the gauges. Once I unhook everything I check the Schrader valves for leakage. That takes care of a good 90% of the issues.

Other things that come to mind are the power wire pigtail on the compressor has been cut by the loom in the past from vibration and caused weird issues check that. You can remove the cover on the front of the compressor to watch the clutch and make sure it’s turning the compressor. You should be getting 12 volts to the compressor when it’s commanded on. There is an electrical connection going to the ATC box that is behind it towards the fuse panel that supplies power, ground, and communication to everything for the climate control. The ATC box is under the operators seat. The ground in that connection has gotten hot in the past and melted the plastic. I have had systems work for a bit then when that connection gets hot they quit. I have also had compressor bearings fail and the compressor does not leak freon, it was obvious when I found it but… Remove the belt and make sure the compressor pulley doesn’t move excessively. If I think of anything else I’ll post it.
 

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Discussion Starter · #38 ·
Thanks Dialed In for the info. I just forwarded it to my tech. Sounds like this isn't your first rodeo.

This AC issue reminds me of 3 years of misery with the auto steer system in this tractor. Pretty much changed every component and cable during that time trying to get the steering to work properly. Finally, the only component left to change was steering valve, the most expensive. But that's what ultimately fixed the problem and the steering works better than it ever did from new. So it's been about 2 years of this AC BS now, hopefully it's not going to be another year.
 
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