John Deere A/C issue

[Makers Acres]

I’m helping a friend with his John Deere 333G. The AC was acting intermittently on a hot summer day and I figured it was probably a low refrigerant issue. When I opened up the machine, I found the compressor was never engaging. I disconnected the power plug and was never able to read 12 volts with the machine running and toggling the AC switch. When I put 12v manually into the clutch I can hear it engage. I checked the fuse and it is fine. I tried finding the relay, but no luck. Do any of you know where this is or have the full wiring schematic? Or perhaps any other suggestions?

Thanks!

 

[mg2361]

Has the pressures been checked? Did it get cold when you hot wired the compressor?

Complete serial number required to get schematics.

 

[Makers Acres]

I had a gauge on it on the low pressure side and it was high, but the compressor was not running at the time, so I figured that was normal. When I hot wired it I heard the clutch engage, but I was not running the engine at the time. I did not want to force it to do something if a safety system was preventing it.

Serial is 1T0333GMEMF393914

 

[mg2361]

Check your messages.

 

[Makers Acres]

Thank you!

 

[Makers Acres]

Well I looked over the schematic and I was hoping to find a hidden relay somewhere I didn’t know about, but that does not appear to be the case. Looks like I have a freeze switch to check and a high pressure switch to check. Do you happen to have diagram that shows where these are? Looks like the High Pressure Switch is B9 and the Freeze switch is B10. Thank you!

 

[mg2361]

B9 is just behind the HVAC unit, in the engine compartment, left side of the machine. B10 is next to the blower motor in the blower box. Check your messages.

 

[Makers Acres]

B9 is just behind the HVAC unit, in the engine compartment, left side of the machine. B10 is next to the blower motor in the blower box. Check your messages.

Once again, you are awesome!!! Thank you so much!

 

[Mrwizard]

Any way to get at the freeze control switch (B10) without removing the whole AC module through the cab.

I thought I could get access by removing the hood and sheet metal but according to the $100 repair manual I just downloaded that's not how its done. Anyone cut an access panel in the blower box before?

 

[Makers Acres]

That was a huge pain in the ass! I had to get access to this switch. I had to raise the Cab and then I had to unbolt that entire unit. Then there were screws around the box and adhesive too and it took a while to get it all apart so I could get to that switch.
Are you sure this is bad or are you just trying to test this? This is what I thought was wrong with my friends. I tore everything apart and found the switch was good. Before I confirmed this, I found the manufacture of the switch and reached out to them for troubleshooting. They were helpful and sent me some info to test it. If I remember correctly, you can get to the connector outside of that box, so you can easily bypass that switch and test it without having to take the box apart!
I also bypassed B9 for a split second just to make sure the compressor clutch would in fact engage. I'm not recommending this, if the system is over pressure, something could blow up!
I did find out that the High/Low Pressure switch was causing the system not to trigger the compressor clutch. I bought one of those refill kits from an auto parts store and tried filling the system with the AC turned on and by damn, the compressor clutch kicked on. This led me to discover that there was a small leak in the system causing it from building proper pressure and was not related to B10 or B9.

Hope this helps! I did film all of this and will get around to making that video on my YouTube channel someday!

 

[Mrwizard]

I also downloaded a schematic, no voltage at pressure switch, switch is closed.
Voltage on red & Org wires that feed everything in the box but no voltage coming back from the freeze switch (green wire to pressure switch). There is no way I want to tear all that apart when the switch is right there behind a layer of composite material. Do you remember if you just jumped across the leads on that switch? The trail stops at that Freeze switch as far as probing and ohming out. Thanks for the reply!

 

[Makers Acres]

IT'S A TRAP! That is the same thing I thought too as I had the same problem when checking it. The freeze switch needs power in order to work and the troubleshooting in the diagnostics manual is not correct! I chased this problem round and round and found that it was related to the HIGH/LOW pressure switch because the system was under pressure. It says it's only a high pressure switch, but it believe it is also a low pressure switch based on the way it behaved. See if you have voltage on one of the legs of the B9 switch when the system is running. If you do, I bet if you bypassed it, the compressor would engage! But like I said before, only do this briefly, because you are bypassing a major safety feature.
If that doesn't work, I can also upload my raw videos if you want to look at some of the things I did.

 

[Mrwizard]

Yea, I had power to the freeze switch, both sides of harness pigtail, no power out (probe both sides of pigtail).
Pressure switch closed machine off, put 12V to pressure sw pigtail to compressor and ran compressor 20 sec with meter across press switch, switch stayed closed which would indicate (along with gauges machine off static chg) . So in my case the logical problem is the switch. Gonna raise the cab and see if I can get to the bulb portion of the switch without pulling the AC unit. I will post here what I find out.
Again, Thanks for the response. If not for all the DEF BS on these machines maybe they wouldn't be built like Rubik's cube, and when you pay 60K for a 2017 machine with low hours you shouldn't have to pay $45 for a schematic and another $100 for a repair manual! That really rubs the wrong way! At least our JD dealer is cool with helping out with info, we spend a lot of money there... but still have to BUY manuals.

 

[Mrwizard]

In case anyone else needs to test this switch, I called Reddot and made a pdf of how to test. Also Makers Acres is correct also about the pressure switch, reddot confirmed its a binary high low switch.

 

[Makers Acres]

Yea, I had power to the freeze switch, both sides of harness pigtail, no power out (probe both sides of pigtail).
Pressure switch closed machine off, put 12V to pressure sw pigtail to compressor and ran compressor 20 sec with meter across press switch, switch stayed closed which would indicate (along with gauges machine off static chg) . So in my case the logical problem is the switch. Gonna raise the cab and see if I can get to the bulb portion of the switch without pulling the AC unit. I will post here what I find out.
Again, Thanks for the response. If not for all the DEF BS on these machines maybe they wouldn't be built like Rubik's cube, and when you pay 60K for a 2017 machine with low hours you shouldn't have to pay $45 for a schematic and another $100 for a repair manual! That really rubs the wrong way! At least our JD dealer is cool with helping out with info, we spend a lot of money there... but still have to BUY manuals.

Ya, the CAT manual for mine is over $1K. Just F'ing nuts. BUT... There is a user on here that has almost every manual. His name is Tool_King I believe. If you can't find him, message me and I will send you his info.

To get to that switch, you have to take that AC box apart. I was able to do this in place, but it really sucks. You have to break seals, gaskets and drop screws and nuts into the abyss!. I can send you the raw videos of the disassembly if you want to reference them.

 

[Mrwizard]

Gonna let everything hang, fold hood hinge over and remove the window sheet metal and everything over the box.
Should be able to get to it then. Wont be fun... Thanks for the reply

 

[Makers Acres]

Good luck! Let us know how it turns out!

 

[Mrwizard]

Well can definitely get it without pulling entire unit. Only thing is you have to tweak the window trim a bit to remove but it bolts back down fine as its thin. I'm attaching a few pics including the 0 voltage test on the freeze switch and the test procedure I typed up from Red Dot.