JD 6920S A/C problems

[Amolnar185]

Hi,
I have the following problem with my JD6920s. The AC compressor runs fine when turning on the engine for the 1st time a day, (cools cabin pretty well) and after 10min of operations it cuts off and only turns back on once i shut down engine and let it cool off after 1hour.

I bought JD second hand and AirCon did not work when i bought the tractor. I had the aircon just serviced with gas but seems that was not the problem. Replaced the pressure switch AL168231 located at receiver dryer, changed the relay on fuse table but still no luck....any help/thoughts are welcomed.

 

[Tractortech]

Now Then..
Who serviced the gas?? How much gas was put in and how did you find the correct recharge weight?? Was it low on gas when tested?? Are the filters clean?? Are the evaporator and condenser clean??
Does the tractor have simple Air conditioning or automatic climate control??

 

[haybob]

Never had trouble with jds but I know you can over chill and freeze some systems up. Try turning the temperature up a little bit if you haven't tried it already.

 

[Flat 10]

Temperature probe in condensor under seat?

 

[Amolnar185]

Now Then..
Who serviced the gas?? How much gas was put in and how did you find the correct recharge weight?? Was it low on gas when tested?? Are the filters clean?? Are the evaporator and condenser clean??
Does the tractor have simple Air conditioning or automatic climate control??

It is equipped with simple air conditioning
It was not low on gas when tested, but given aircon did not work when I bought it I had it serviced.

Yes both evaporator and condenser are clean.

 

[Amolnar185]

Temperature probe in condensor under seat?

oh boy! that seems to be fun to get to...I will try that during weekend

 

[Timbo]

Ok, before you start attacking the seat etc, run the tractor up for a while til the a/c cuts out - with the system turned on, check for power at the compressor clutch pig tail wire with a 21w or stronger bulb and report back to us please.

 

[Timbo]

Temperature probe in condensor under seat?

Evaporator.

 

[Amolnar185]

Ok, before you start attacking the seat etc, run the tractor up for a while til the a/c cuts out - with the system turned on, check for power at the compressor clutch pig tail wire with a 21w or stronger bulb and report back to us please.

So, today I had my multimeter with me and checked voltage going to the a/c compressor with system turned on. When a/c compressor turns it receives 12.8-13.2V; however, when it cuts out completely after ±10 min of operations and system is trying to get the compressor to turn back on to provide cool air, compressor only receives 5.8V -6.8V. it seems as system would want to turn the compressor back on but it does not receive sufficient Voltage to engage...Thanks

 

[Timbo]

Have you got a wiring diagram for the tractor, since at this point, either you have a poor connection at one of the multiplugs on the way to the compressor, or the control unit is faulty.

 

[Amolnar185]

Have you got a wiring diagram for the tractor, since at this point, either you have a poor connection at one of the multiplugs on the way to the compressor, or the control unit is faulty.

I don't. is there somewhere i can download it from? thanks

 

[Matthew Britton]

Have a look on eBay. There is a chap who sells John Deere workshop manuals on pdf. Would have thought it would be in there.

 

[Flat 10]

Slightly off topic. I have a 6920 and the larger diameter pipe that runs from the evaporator (thanks @Timbo) to the compressor chafed through near the exhaust and sprayed all the oil on the hot exhaust which was quite alarming. Anyway I've had the new pipe in stock for a while and today was the day I finally decided to brave it but i'm struggling to fit it. The new one has more rigid steel pipe and less rubber but the bit i'm struggling with is where it goes into the cab under the seat. Got seat all out ok but struggling to undo allen key where it joins block that has the narrow diameter one fitted to it too. When I manage that how is the rubber grommet fitted where it enters the cab? All advice gratefully received @Tractortech @Phil P thanks

 

[Timbo]

With alot of swearing basically. Locate both ends and have fun wresting it under the cover by exhaust. Lift the evap out of housing for better access to the clamp bolt. Replace o-rings both ends. When in situ, massage it to fit nice without it rubbing the frame by oil filter.

 

[Phil P]

Slightly off topic. I have a 6920 and the larger diameter pipe that runs from the evaporator (thanks @Timbo) to the compressor chafed through near the exhaust and sprayed all the oil on the hot exhaust which was quite alarming. Anyway I've had the new pipe in stock for a while and today was the day I finally decided to brave it but i'm struggling to fit it. The new one has more rigid steel pipe and less rubber but the bit i'm struggling with is where it goes into the cab under the seat. Got seat all out ok but struggling to undo allen key where it joins block that has the narrow diameter one fitted to it too. When I manage that how is the rubber grommet fitted where it enters the cab? All advice gratefully received @Tractortech @Phil P thanks

I have a cut down allen key for that job, it’s a tight fit because of the bend in the pipe.
The grommet is just a case of poking it back in with a screwdriver, probably take a few goes though as you usually end up pushing it through and have to start again?

 

[Drillman]

Sounds to me as though it could be freezing up which is either a sensor related issue or has moisture in the system.

Was it vacced out and receiver drier replaced when serviced?

If you tap the compressor when tractor is running but aircon not working does it click and start running? If it does it maybe needs a shim out of compressor clutch.

Temp sensor in condenser is another thing that might cause your fault.

At end of day you gotta remember there’s air con men and aircon men. The good ones will have a thorough knowledge of cooling systems and will get it going no bother.

The ones who done a days training course will struggle.

 

[Flat 10]

I have a cut down allen key for that job, it’s a tight fit because of the bend in the pipe.
The grommet is just a case of poking it back in with a screwdriver, probably take a few goes though as you usually end up pushing it through and have to start again?

About to go and get brutal with the grommet....

 

[David.]

That is what Tigerseal was invented for

 

[Flat 10]

Never used it. Probably would do the job but I will try to re use grommet

 

[Timbo]

Never used it. Probably would do the job but I will try to re use grommet

I always push them through into the HVAC box in the cab, then work them back with small screw driver alittle at a time.