John Deere 4230 A/C 70 degree vent temp

[Crobby110]

Got a 4230 tractorit has a new compressor, condenser, txv, filter/drier, and blower upgrade switch..charged to 3.25 lbs r-134a

Only gets to 70 vent temp even with txv sensing bulb totally off suction line. Ive adjust txv so many times and replaced it twice. Pressures are good and the lines sweat nicely. But it isnt cooling. The line the txv mounts to going into evap is twisted and bent a little, but I bent it backdoesnt seem to be an issue..I have bo more ideas.

 

[Roger in Iowa]

What is your ambient temperature?
Condensor and evaporator clean?
Cab filter clean?

 

[JD Dave]

Define pressures are good. On a hot day, high side with r134 could/should be 250 and low side 30. Is the low side inlet to the compressor cool/cold? Did you thoroughly evacuate the system? Seems if the low
side lines are cool all the way to the compressor, then the evaporator is cold and if there's sufficient air flow you should be good to go. Nevertheless, out in the field when everything gets steamy, - a dirty
condenser can also be a problem. Suggest inspecting and powerwashing the consdenser.

 

[cornerpost]

Make sure heater valve is off. Even install a valve in heater hose.

 

[NoDakInMN]

My advice is to get someone who knows what he is doing to look at it. The fact that you are pulling the TEV bulb off and adjusting the valve repeatedly and even replacing the valve, without knowing the super heat, tells me you are in over your head here. Not to be mean or critical, but you can ruin a new compressor that way.

Thermostatic Expansion Valves control superheat. Period. Taking a bulb off can flood liquid refrigerant back to the compressor and take out the valves in the compressor by slugging it with liquid refrigerant. Liquids do not compress, so the valves take the punishment. Blindly cranking on the expansion valve can do the same thing.

These are not complex systems, but you do need to know what you are doing. And right now, if it were me, I would have to do a base assessment on all components to find out what is working and what is not, before even beginning to guess what is wrong.

 

[4520BW]

Never seen an adjustable txv from deere. I agree that it could be heat valve open or leaking thru. Try some vise grips on heater hose to see if that helps.

 

[4240 Turbo]

That sounds like a overcharge of 134 possibly. I find that these expansion valve type systems in my equipment (andI do know and understand air conditioning and am licensed) that the charge pressures function more effectively if low side is kept slightly lower. I charge from nothing up to 150 hi side slowly on a warm/hot day. then monitor temps and slowly add but don't worry much about low side unless it spikes too high. Sometimes an expansion valve seems to work at a lower low pressure than an orifice tube system. Remember that the system has no accumulator, meaning that the refrigerant coming from the evaporator to compressor is supposed to be evaporated by the time it leaves evaporator as opposed to an accumulator is an overflow for extra liquid refrigerant.

Now, No mention of oil. How much oil is in here? no need for much more than 8-10 ounces total, 12 at most I say. If you added oil, and there was oil already in system, or compressor was changed that had oil and more oil was added, need to make sure not too much oil.

Now, what freon?? R134a... Pure new r134a, or recycled 134a or r134a cans with oil charge and stop leak and leak detector?

Are we using a reputable set of r134a manifold readings that PROPERLY go to -0- on both gauges at atmospheric exposure? is it a reputable manifold set like matco or snapon or mac or mastercool or robinair or fjc or a generic fly by night run-what-you-brung telling us bogus readings?

Now if you are still confident to this point of your current predicament... Simply run ac and feel drier unit for unifrom heat. If uniform heat, move on. If not, it is compromised and evaluate why and probably replace.

Next is with ac running, pour cold water over condenser and monitor temps and pressures, see if condenser is doing IT'S job.

Now, assuming all these are are ok and register temps are still not down, is it building ice? we never checked for ice? ice can block air flow and then nothing cools due to air flow is restricted that air can't be cooled.

finally we need to check insulation in roof to see if air is being forced through evaporator core. If these suggestions are over your head or you don't have time to evaluate it properly, hire a specialist.