L3430 AC compressor not kicking in

   / L3430 AC compressor not kicking in #1  
W

WileyG

Bronze Member
Joined
Sep 4, 2015
Messages
59
Location
Guntersville,AL
Tractor
Yanmar YM3000 Kubota L3430HSTC
This is a well maintained 2004 L3430 HSTC with 1005 hours on it. The screens are clean and the freon is good. Before I start trying to trace wires tomorrow I wanted to ask if there is a relay in the AC circuit that may have died. Over the years since 2016 when I bought it I have had an intermittent problem with the AC not cooling on about 3 occasions but each time I continued to run the tractor and the AC eventually started working. This time, the compressor clutch is not responding at all, no click, no screeching, nothing. The 7.5A fuse is good. A few days ago it did this with my son and he said it finally started working. I wasn't aware of this until yesterday when it didn't work for me and he told me. SO......... any input is appreciated.
 
   / L3430 AC compressor not kicking in #2  
Yes it has a relay.

I would test the relay.

It is in the roof of the cab.
 
   / L3430 AC compressor not kicking in #3  
What are the high and low pressures when it's running/not running? What is the ambient temperature when you check? You can't diagnose the AC without knowing that. "Good" doesn't mean anything.

The compressor is typically controlled by the thermostat inside the evaporator case. There may also be a high/low pressure switch. This switch is to save your compressor. Find the connector that powers the compressor and verify the compressor clutch "kicks in" by jumping 12v to that compressor wire. DO NOT leave this wire connected. It's to test the compressor clutch coil only.
 
   / L3430 AC compressor not kicking in
  • Thread Starter
#4  
Tinhack said:
What are the high and low pressures when it's running/not running? What is the ambient temperature when you check? You can't diagnose the AC without knowing that. "Good" doesn't mean anything.

The compressor is typically controlled by the thermostat inside the evaporator case. There may also be a high/low pressure switch. This switch is to save your compressor. Find the connector that powers the compressor and verify the compressor clutch "kicks in" by jumping 12v to that compressor wire. DO NOT leave this wire connected. It's to test the compressor clutch coil only.
Click to expand...
I don't have gauges to check pressures. The ambient temp was 82 degrees. Since the compressor clutch isn't engaging at all I suspected something electrical....a relay.... I will momentarily jump 12V to it tomorrow to see if it engages and I will also try to track down that relay that diesel85 references.

Thank you both for your input. I need to bush hog 14 acres next weekend and the forecast says 90 degrees so I REALLY need the AC.
 
   / L3430 AC compressor not kicking in #5  
Due to your statement ""I don't have gauges to check pressures"" what other means are you using besides "guessing" that your tractors AC has correct amount of refrigerant? I suggest for you to have an AC knowledgeable person check your tractor's refrigerant pressures with gauges. If one heater hose don't contain a manual coolant shut off valve I suggest you install a manual shut off valve
 
   / L3430 AC compressor not kicking in #6  
diesel85 said:
Yes it has a relay.

I would test the relay.

It is in the roof of the cab.
Click to expand...
Interestingly, Kubota uses identical relays for everything (under the roof on the left side facing forward) so you can mix and match to see if one is bad. DO NOT buy a replacement relay from your dealer as they charge around 70 bucks for each one and you can get them from Digikey for about 15 bucks each, shipping included. I keep a spare on in the shop all the time, just in case.
 
   / L3430 AC compressor not kicking in #7  
Tx Jim said:
Due to your statement ""I don't have gauges to check pressures"" what other means are you using besides "guessing" that your tractors AC has correct amount of refrigerant? I suggest for you to have an AC knowledgeable person check your tractor's refrigerant pressures with gauges. If one heater hose don't contain a manual coolant shut off valve I suggest you install a manual shut off valve
Click to expand...
Jim is stating the best course of action to address the issue. Something that Kubota don't do is install a shutoff valve in either heater hose but is should ne done anyway. Just a tiny amount of bleed past the rotary heater control valve (under the roof) will severely compromise the cooling of the ac in the summer. Put the valve under the hood (bonnet) somewhere convenient. A WOG ball valve is the ticket.
 
   / L3430 AC compressor not kicking in #8  
Heater coolant line on my '91 JD 4255 has had a manually operated coolant heater hose valve installed since I purchased it used in '93. That valve has remained closed because a tractor heater in Sunny Texas Winter temps is rarely needed but after a few minutes of operation then one needs AC to cool on lower setting
 
   / L3430 AC compressor not kicking in #9  
Without the proper refrigeration tools, diagnosing and fixing any ac (tractor, house or car) is a total crapshoot and stay away from those 'fixes in a can products' as you can overcharge a system and destroy it easily. All refrigeration systems take a very specific amount of refrigerant so guessing don't count and could cost you big bucks in the end.
 
   / L3430 AC compressor not kicking in
  • Thread Starter
#10  
Tx Jim, I get it that the coolant pressures need to be checked. My intention is to eliminate a lack of voltage or other electrical failure before I get someone else involved OR buy gauges myself. Just the elementary stuff that doesn't cost me anything is what I want to eliminate. AND, I will install a ball valve on one or both heater hoses today.

Thank you all for your input.
 
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