MF6400 Air Con Issue

Steevo · May 16, 2019

Had an air con guy out recently as the air con wasn't working properly on this tractor. Tested, re-gassed etc. but still not working. He's suggested calling the dealer as thinks it might be a laptop job to plug in an test/diagnose.

By all accounts the temperature switch/dial in the cab doesn't click when it reaches temperature and has advised it "might be the thermal unit".

Anything else worth considering before picking up the phone to the dealer?

Massey Ferguson 6480 · May 16, 2019

Is it a climate control unit? Temperature comes up digitally or just normal control knobs?

Steevo · May 16, 2019

Just normal control knobs-fan, hot/cold and air con temp.

Massey Ferguson 6480 · May 16, 2019

Steevo said:
Just normal control knobs-fan, hot/cold and air con temp.

Ah sorry, had an issue before with the climate control not working properly and requiring calibration but had no problems with normal controls

Speedstar · May 16, 2019

Steevo said:
Had an air con guy out recently as the air con wasn't working properly on this tractor. Tested, re-gassed etc. but still not working. He's suggested calling the dealer as thinks it might be a laptop job to plug in an test/diagnose.

By all accounts the temperature switch/dial in the cab doesn't click when it reaches temperature and has advised it "might be the thermal unit".

Anything else worth considering before picking up the phone to the dealer?

on a standard 6480 you do not need a laptop to sort the air con ,
check has it got gas in it ?
is the compressor or going in & out ?. Check the relays as they can be trouble

Steevo · May 16, 2019

Speedstar said:
on a standard 6480 you do not need a laptop to sort the air con ,
check has it got gas in it ?
is the compressor or going in & out ?. Check the relays as they can be trouble

Thanks. Yes the air-con guy has regassed it so it’s full. He checked wiring from cab roof onwards and apparently it’s all good, but no power getting to the wiring that goes to compressor etc hence he suspected an issue prior to this, noted as the “thermal unit”.

Speedstar · May 16, 2019

Steevo said:
Thanks. Yes the air-con guy has regassed it so it’s full. He checked wiring from cab roof onwards and apparently it’s all good, but no power getting to the wiring that goes to compressor etc hence he suspected an issue prior to this, noted as the “thermal unit”.

when you say no power , have you by passed the low & high switches to get the compressor to run ?

Steevo · May 16, 2019

Speedstar said:
when you say no power , have you by passed the low & high switches to get the compressor to run ?

Not a clue if i’m honest.

Lofty1984 · May 16, 2019

As speedy says I had a similar problem temporary fix was to run a cable direct from the compressor to the 3 pin plug in the cab

Steevo · May 16, 2019

Thanks. The air con guy seemed to know his stuff and does tractors a lot. He said he thought the air-con was part of a CANBUS system and was concerned about making things worse.

Potentially not the case then based on the above?

Steevo · May 16, 2019

Speedstar said:
when you say no power , have you by passed the low & high switches to get the compressor to run ?

Would this be a case of bridging the terminals behind the temp switch in the cab?

The air con guy suggested the switch didn’t click so he thought it unlikely there was power going to it.

Speedstar · May 16, 2019

Steevo said:
Would this be a case of bridging the terminals behind the temp switch in the cab?

The air con guy suggested the switch didn’t click so he thought it unlikely there was power going to it.

you may be better to get the mf guy out to it if you not sure how it all works .

Bullring · May 16, 2019

Mine didn't work but it turned out to be the relay, does it click and kick in the compressor when turned on.

Steevo · May 16, 2019

Bullring said:
Mine didn't work but it turned out to be the relay, does it click and kick in the compressor when turned on.

No, no clicking.

essexpete · May 16, 2019

Bridge out the thermoset? How I diagnosed my Ford NH.

made2fail · May 17, 2019

hi, i'd put all the money in my wallet on the relay at fault, changed loads of these. its the worse relay to get out from the fuse box.its in the top left hand corner & sometimes need to lift the hyds lift panel out to gain extra access to the relay.
sometimes if you have the ac on as you rock the relay you hear the compressor clutch click

Dave6170 · May 17, 2019

It was the relay on mine last week.

raiderz · May 17, 2019

I had problem on a 6616, the receiver dryer had failed and filled the pipes going up the cab front pillar to the radiator at the top with tiny little grey balls, what a mess on it was for the fitter to clean it all out. Glad it was still under warranty though, most of the components were filled with these balls and needed replacing.

Steevo · May 17, 2019

Speedstar said:
on a standard 6480 you do not need a laptop to sort the air con ,
check has it got gas in it ?
is the compressor or going in & out ?. Check the relays as they can be trouble

Bullring said:
Mine didn't work but it turned out to be the relay, does it click and kick in the compressor when turned on.

made2fail said:
hi, i'd put all the money in my wallet on the relay at fault, changed loads of these. its the worse relay to get out from the fuse box.its in the top left hand corner & sometimes need to lift the hyds lift panel out to gain extra access to the relay.
sometimes if you have the ac on as you rock the relay you hear the compressor clutch click

Dave6170 said:
It was the relay on mine last week.

Thank you all. Seems there's a pattern here.

Worth checking the relay as a cheap fix before shelling out again.

farmerphilly · May 17, 2019

I had the same issue and yes it was the relay. I swapped it with one from lights on the steps and they flickered on and off. New relay for about a fiver and been ok since. You might need to take the trim off around the pto levers to see the relay as I seem to remember it is in the very top left of the circuit board.

MF6400 Air Con Issue

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