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Air conditioning issues on cousin's JX75


russ_alabama

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My cousin's got a JX75 he bought new.  Been a trickle of air conditioning issues over the years.  This past season it got to cycling constantly and would squeal the belt (especially when it was hot ambient temp).  He just had a local shop replace the expansion valve and dryer.  Now the compressor kicks on 7sec, off for 15sec, same cycle continuously.  When kicked on, his high side measures 175lb, 30lb on the low side.  That's at 79F degrees ambient today.  In the summer, he says it'd normally go up to 250-275lb on the high side in those cycles on.  

I'm a note taker here and not a A/C man... but, I figured as many of those tractors sold as there was, there was libel to be someone on here that worked out the kinks... I've heard those were more problematic than some on the HVAC stuff.  

Any ideas?  

 

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A couple of things to check. Is the condenser coil(by front ) clean. That can cause higher than normal high side pressures. It can be tripping the high pressure switch and cause the cycling.30lbs on the low side can be ok. The switches  I am guessing should be 25 on the low and 250 on the high. Is there an electric fan or is it shaft driven all the time?, poor switches can cause of short cycling. Poor air in the cab can be plugged coil, diverter plates closed so no airflow through the coil. Dirty filters etc. Was into a JD chopper once that was short cycling and found there is a baffle between the heat and cooling and the cable was not moving the baffle into the cooling position so the air was going through the heat coil but not the cooling and it was cycling on the low pressure switch. It had a full charge in the system. some things to look for.

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2 minutes ago, VacDaddyt said:

A couple of things to check. Is the condenser coil(by front ) clean. That can cause higher than normal high side pressures. It can be tripping the high pressure switch and cause the cycling.30lbs on the low side can be ok. The switches  I am guessing should be 25 on the low and 250 on the high. Is there an electric fan or is it shaft driven all the time?, poor switches can cause of short cycling. Poor air in the cab can be plugged coil, diverter plates closed so no airflow through the coil. Dirty filters etc. Was into a JD chopper once that was short cycling and found there is a baffle between the heat and cooling and the cable was not moving the baffle into the cooling position so the air was going through the heat coil but not the cooling and it was cycling on the low pressure switch. It had a full charge in the system. some things to look for.

Thanks for some tips there... He did add a electric fan in front of the condenser to pull more air thru it, and he's pretty obsessive about keeping radiator and condenser cleaned out.  Don't think he's changed any switches yet.  And don't think he's checked the diverter plate either.  I'll get these things to try to him... he's had good service out of the tractor, apart from the A/C... he's still got his 986 he got new, and an 856, a 504 on halves with his son, and a B, C, H, and A (and some a 50 Massey and 1100 Massey).  

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If I had to guess, I'd say it's cycling because of low side pressure switch. The pressures you gave are fine for 134a. But gauges are off some times. You said a shop replaced the expansion valve and dryer and now your having this problem. I would suspect the expansion valve then. Lots of bad techs out there. If it's an orfice type expansion valve there could be trash in the orfice or under charged. If it's a thermostatic expansion valve then it's probably adjusted wrong. As stated by VacDaddyt. If your not getting air flow across the evaporator coil then it will cycle on the low pressure switch also. { and flood back to the compressor which is very bad }. It would be best to take it to a good HVAC tech and let him check it out / straighten out the other shops mess.

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3 hours ago, MarkG said:

If I had to guess, I'd say it's cycling because of low side pressure switch. The pressures you gave are fine for 134a. But gauges are off some times. You said a shop replaced the expansion valve and dryer and now your having this problem. I would suspect the expansion valve then. Lots of bad techs out there. If it's an orfice type expansion valve there could be trash in the orfice or under charged. If it's a thermostatic expansion valve then it's probably adjusted wrong. As stated by VacDaddyt. If your not getting air flow across the evaporator coil then it will cycle on the low pressure switch also. { and flood back to the compressor which is very bad }. It would be best to take it to a good HVAC tech and let him check it out / straighten out the other shops mess.

Seems like a good shop, but it don't mean there can't be a mishap... was googling the expansion valve for that model and it looks like they refer to it as a thermastic valve... also am seeing trash in the system, along with moisture, mentioned a lot... I'll forward the tips... thanks!  

 

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On a JX series, there is no low pressure switch in the factory AC system in the cab. You had one pressure switch, right by the receiver-dryer. It served as both the high-pressure switch during operation(shuts the compressor off above 360psi) and a low-pressure switch (prevents clutch engagement if the pressure is below 29psi). Simplifies things a little bit for you.

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Well there you go^^^. If this is true and your low side pressure is at 30 then your low pressure side of that switch is kicking your compressor out. So the first thing I would do if it were me is throw some die and a charge in it. Since it’s cold now don’t get your high side pressures too high but get it up over 200 where your low side is a little higher and see what happens. Sounds like they swapped out some parts and either didn’t charge it enough or more likely he has a small leak and now it’s gotten low enough to cycle that low pressure switch.  Just my thoughts. NOW if you throw some in and pressures are funky then it would lead to other things. 

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