mf 6400/7400 t3 air con question

[davidroberts30]

my 7480 the compressor is engaged with the switch in the cab in the off position,hence compressor running continuously and icing things up

pull the tail off on the back of the compressor and it cuts out

ive heard there are a couple of relays somewhere about the cab but where??
anything else to check over?


cheers

 

[farmerphilly]

Relays in fuse box. Check position in the instruction book. I had the opposite problem which turned out to be the relay but it wouldn’t turn on.

 

[davidroberts30]

After 15 minutes running the 50amp relay was warming up then causing problem

I changed it (new 1 was 70 amp) and half hour running it was still cycling as normal

For now......

 

[davidroberts30]

didnt fix it

i'll have to get up in the roof...

 

[Always wandering]

Relay r 28 in fuse box worst one to remove either that or thermostat in roof blue box with probe into evaporator and wire running forward to switch above your head

 

[davidroberts30]

Relay r 28 in fuse box worst one to remove either that or thermostat in roof blue box with probe into evaporator and wire running forward to switch above your head

There's 2 relays behind the radio(1 for a.c. and 1 for water pump)
And that 1 in the fuse box

 

[Tullyvernon]

There are relays behind the climate control unit that i have seen cause compressor to run continually.

 

[Always wandering]

Is it standard ac or climate control

 

[Cowabunga]

Is it standard ac or climate control

99% of all 7400 series will have climate control. Which is no better really than standard air-con except that there is far more to go wrong and the extra stuff is expensive stuff. Plus every time you open the door for more than a few seconds on a hot day will have the blower roaring away needlessly. So nobody with standard air con should worry that they are missing out on anything. Its different than a car, which may have dual zones and will vary the vent openings as appropriate. There's none of that in the tractor where all the climate system does really is to alter the blower speed as an extra feature.

 

[davidroberts30]

There are relays behind the climate control unit that i have seen cause compressor to run continually.

Yes behind the radio

And climate control