8240 Air Conditioning

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The Pretender
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8240 Air Conditioning

Post by The Pretender » Thu Jun 01, 2017 7:23 pm

We have a 1995 FORD 8240, blue roof, metal rear fenders that the air conditioning isn't working on.

Normally, when I turn a tractor on that has AC the compressor clutch will click when I switch the ignition on. Not so with this tractor today.

All of the fuses are good, according to my multimeter. I'm a novice with this tool but think I found some volts in the plug on top of the compressor, 6 or 9 depending on how I wiggle the probes in the plug. The AC dial in the cab was replaced last year and it's worked since. It's an electrical issue I think, but don't know who to check things.
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NQIT
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Re: 8240 Air Conditioning

Post by NQIT » Thu Jun 01, 2017 7:43 pm

Have you tried opening the windows and doors?
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defender
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Re: 8240 Air Conditioning

Post by defender » Thu Jun 01, 2017 8:01 pm

blowing the compressor clutch out with the airline might help if it has a lot of shit in it and sat for a while and also if the pressure has dropped too low in the system it will stop it working
if you link the wires going to the pressure switch and the clutch clicks it will tell you low pressure
don't run it with the wires bridged though as it wont do the compressor any good
other than that ,no idea as that's what I try before calling repair guy in

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Coltheox
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Re: 8240 Air Conditioning

Post by Coltheox » Thu Jun 01, 2017 10:36 pm

The Pretender wrote:We have a 1995 FORD 8240, blue roof, metal rear fenders that the air conditioning isn't working on.

Normally, when I turn a tractor on that has AC the compressor clutch will click when I switch the ignition on. Not so with this tractor today.

All of the fuses are good, according to my multimeter. I'm a novice with this tool but think I found some volts in the plug on top of the compressor, 6 or 9 depending on how I wiggle the probes in the plug. The AC dial in the cab was replaced last year and it's worked since. It's an electrical issue I think, but don't know who to check things.
Almost certainly needs recharging, IMO.
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footsfitter
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Re: 8240 Air Conditioning

Post by footsfitter » Thu Jun 01, 2017 11:39 pm

The Pretender wrote:We have a 1995 FORD 8240, blue roof, metal rear fenders that the air conditioning isn't working on.

Normally, when I turn a tractor on that has AC the compressor clutch will click when I switch the ignition on. Not so with this tractor today.

All of the fuses are good, according to my multimeter. I'm a novice with this tool but think I found some volts in the plug on top of the compressor, 6 or 9 depending on how I wiggle the probes in the plug. The AC dial in the cab was replaced last year and it's worked since. It's an electrical issue I think, but don't know who to check things.

That multimeter will get you into trouble eventually :wink:

I think IIRC 40+60series and TM's are basically similar in principle but early 40 series had a funny wiring loom up in the roof, at 1995 it may be the later type like this-

They all have an electronic potentiometer in the roof "cold" switch

Image


which connects to an electronic thermostat

Image


there will also be a pressure switch up in the roof

Image

(I can't remember if there is another switch on down near the compressor or on the pipes to the condenser in front of the rad- on tm's theres one right next to the compressor that fails a lot- it also controls the engine fan electric clutch)


Pull the connector on the compressor, if it has 2 wires one will be earth the other the + feed to the clutch coil, it may just have one though. get yourself a length of wire connected to a good live feed and touch it to the clutch feed to see if it clunks, if it does then run the tractor and carefully connect up the wire again and see if it runs- put your hand on the small and large pipes coming out of the compressor- small get hot large goes cold. if it does this then connect the compressor wiring back up and try running the AC having accessed inside the roof and joining the two wires on the pressure switch together- if it runs then you may have low gas or an electronic problem. You should be able to rule out the low gas by seeing if with the two wires pulled off the switch and everything at rest you get a circuit through the switch

On the roof pressure switch, pull the wires off and test with your meter to see if the one coming from the potentiometer & thermostat becomes live when with the ign and blower on you turn the AC knob on and down to cold- I expect it won't pointing to either the pot has gone again or the electronic stat has this time.

If you can get this far then its easy to convert the system to an old fashioned manual stat the AP air can supply

Image

You scrap the old knob and pot + electronic stat, fit this- putting the sensor tube in the middle of the evaporator (the electronic one may be in the end of the 'vap - I like them in the middle) and a little bit of wiring is all there is to it.


See what you find
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essexpete
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Re: 8240 Air Conditioning

Post by essexpete » Fri Jul 07, 2017 10:06 pm

footsfitter wrote:
The Pretender wrote:We have a 1995 FORD 8240, blue roof, metal rear fenders that the air conditioning isn't working on.

Normally, when I turn a tractor on that has AC the compressor clutch will click when I switch the ignition on. Not so with this tractor today.

All of the fuses are good, according to my multimeter. I'm a novice with this tool but think I found some volts in the plug on top of the compressor, 6 or 9 depending on how I wiggle the probes in the plug. The AC dial in the cab was replaced last year and it's worked since. It's an electrical issue I think, but don't know who to check things.

That multimeter will get you into trouble eventually :wink:

I think IIRC 40+60series and TM's are basically similar in principle but early 40 series had a funny wiring loom up in the roof, at 1995 it may be the later type like this-

They all have an electronic potentiometer in the roof "cold" switch

Image


which connects to an electronic thermostat

Image


there will also be a pressure switch up in the roof

Image

(I can't remember if there is another switch on down near the compressor or on the pipes to the condenser in front of the rad- on tm's theres one right next to the compressor that fails a lot- it also controls the engine fan electric clutch)


Pull the connector on the compressor, if it has 2 wires one will be earth the other the + feed to the clutch coil, it may just have one though. get yourself a length of wire connected to a good live feed and touch it to the clutch feed to see if it clunks, if it does then run the tractor and carefully connect up the wire again and see if it runs- put your hand on the small and large pipes coming out of the compressor- small get hot large goes cold. if it does this then connect the compressor wiring back up and try running the AC having accessed inside the roof and joining the two wires on the pressure switch together- if it runs then you may have low gas or an electronic problem. You should be able to rule out the low gas by seeing if with the two wires pulled off the switch and everything at rest you get a circuit through the switch

On the roof pressure switch, pull the wires off and test with your meter to see if the one coming from the potentiometer & thermostat becomes live when with the ign and blower on you turn the AC knob on and down to cold- I expect it won't pointing to either the pot has gone again or the electronic stat has this time.

If you can get this far then its easy to convert the system to an old fashioned manual stat the AP air can supply

Image

You scrap the old knob and pot + electronic stat, fit this- putting the sensor tube in the middle of the evaporator (the electronic one may be in the end of the 'vap - I like them in the middle) and a little bit of wiring is all there is to it.


See what you find
Our 8340 has a manual stat and it works quite well. When I replaced I bought a generic one as Ernie said it should be eletronic and could not cross ref.

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6920s pilot
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Re: 8240 Air Conditioning

Post by 6920s pilot » Fri Jul 07, 2017 10:20 pm

Anyone got any old school AC refrigerant ?, our old 6640 needs a regas and the management are too tight to replace the condensor etc that is necessary to cope with the polar bear friendly stuff :cry:
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HESSTON4860s
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Re: 8240 Air Conditioning

Post by HESSTON4860s » Sat Jul 08, 2017 7:54 pm

6920s pilot wrote:Anyone got any old school AC refrigerant ?, our old 6640 needs a regas and the management are too tight to replace the condensor etc that is necessary to cope with the polar bear friendly stuff :cry:
Don't need to change the condenser, need to possibly change the receiver/dryer but we never did on the 3050 when it went from R12 to R134a.

You could always do a redneck recharge and fill it up with calor gas !.

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footsfitter
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Re: 8240 Air Conditioning

Post by footsfitter » Sun Jul 09, 2017 12:30 am

6920s pilot wrote:Anyone got any old school AC refrigerant ?, our old 6640 needs a regas and the management are too tight to replace the condensor etc that is necessary to cope with the polar bear friendly stuff :cry:
I might know someone I could put you in touch with. Will PM you the details


HESSTON4860s wrote:
6920s pilot wrote:Anyone got any old school AC refrigerant ?, our old 6640 needs a regas and the management are too tight to replace the condensor etc that is necessary to cope with the polar bear friendly stuff :cry:
Don't need to change the condenser, need to possibly change the receiver/dryer but we never did on the 3050 when it went from R12 to R134a.

You could always do a redneck recharge and fill it up with calor gas !.
The only conversions I have done have been ok with the std condenser but I understand that there are system that cope with R12 but when converted to 134a with its lower efficiency in transferring heat may need a bigger condenser to work effectively.
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RGSP
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Re: 8240 Air Conditioning

Post by RGSP » Sun Jul 09, 2017 8:44 am

footsfitter wrote: The only conversions I have done have been ok with the std condenser but I understand that there are system that cope with R12 but when converted to 134a with its lower efficiency in transferring heat may need a bigger condenser to work effectively.
That's the point really: any refrigeration system ought to work with fluids other than Refrigerant 12, but R12 was chosen because it works very well and most systems were optimised for its use. Other fluids will work, but not as well..

essexpete
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Re: 8240 Air Conditioning

Post by essexpete » Tue Jul 18, 2017 10:30 pm

I would not fancy have the system full of butane or propane.

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footsfitter
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Re: 8240 Air Conditioning

Post by footsfitter » Wed Jul 19, 2017 8:07 am

essexpete wrote:I would not fancy have the system full of butane or propane.
They had one kit fitted to a peaviner years ago - maybe not so bad but in a car in a smash? new gas R1234a is supposed to be slightly more flammable than R134a but not worth worrying so I've read.

The peaviner job was a waste as the installers came from up north, when it wanted looking at, there wasn't anyone down here interested. Another committee decision :lol:
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