Intermittent air conditioning failure

[Oz_Kioti]

A strange air-con problem has recently surfaced in my 5yo Kioti RX8030. Starting a couple months ago, every few weeks, it just won't pump out cold air one day, then either later in the day when the engine's restarted, or the next day, it'll be normal.

When it first happened, I thought "Uh-oh, Maybe I should be more diligent in blowing out the radiator, oil cooler, condenser, and any other things bolted on in front of the fan". Then when it started working again, I thought I'd nailed the problem.

Since then, I've been regularly firing up the air compressor and blowing all the dust and crap out (from the fan side first, to blow the rubbish out the same way it came in), but then it happened again. The magnetic clutch had not pulled in, so that was my first suspect. However 12volts directly to the coil pulled it in, so I'm now left with the likely culprit being either a faulty/failing sensor, or wiring/electrical connection which is preventing the system from working.

When the air-con is working, it's brilliant, so I'm guessing it's not the refrigerant level being low. But as you'd know if you operate a cabin tractor in summer conditions, without air-con, forget it. Park the machine and go get a beer! My next step is to pop the lid of the cabin and do a visual inspection. Bit of a pain to remove light bars and Trimble wiring, but at least the rear of the lid is hinged, so should just be a one man job.

Any ideas?

 

[LittleBill21]

when it fails, check if there is 12v to the clutch, if not it may be a low pressure sensor interrupting it. you would need a wiring diagram though to see if its computer controlled or simply wired in series with the ac clutch relay

 

[Oz_Kioti]

These suggest it's quite straightforward (ie - no computer control):

 

[Threepoint]

I'm assuming you've double checked your belt tension, but just in case not...

I went through a similar frustrating experience a few years ago with my NX4510HC. Turned out to be intermittent belt slippage!

 

[Oz_Kioti]

I'm assuming you've double checked your belt tension, but just in case not...

I went through a similar frustrating experience a few years ago with my NX4510HC. Turned out to be intermittent belt slippage!

Yeah, when it failed for the second time, I checked the tension. It was a bit slack, so I tightened it up to spec. However, I will re-check it now. I had the tractor running about three hours this morning doing some serious chipping of fallen trees (recent storm/cyclone) and air-con was working it's little heart out.

 

[J&K]

Kind of forgot about this. I have had that problem from time to time on my RX last year. I would turn the A/C off then back on and it would work fine. I will definitely check my belt tension. Thanks

 

[Oz_Kioti]

UPDATE: When I first "lifted the lid" of the cabin to reveal the wiring plugs & sockets, relay, aircon ducting, blower, etc, there was much more dust on everything than I expected. Strange, because I've had the four air filters replaced regularly. Then I noticed the foam sealing strip which runs around the perimeter of the cabin frame had never been installed properly. My white lines show where the strip should be:

Then yesterday when my experienced aircon & auto electrician mate was here, after checking for the correct pressures, we popped the lid again. He saw the leaking seal and all the dust and asked if I'd looked inside the ducting at all. I hadn't - with all the linkages and mechanical cables to operate various flaps and diverters, etc, it looked to be a job for someone above my pay grade. Like him!

So he removed the fan blower assembly in front of the evaporator, which revealed the problem:

Some time later, after gently flushing it all off with water, and replacing the main relay which he suspected might have had bad contacts (it did, which a destructive tear-down revealed), he reassembled it all, and it works beautifully again.

So a very happy camper here, and I'm so relieved that he found the problem. It's a wonder it worked at all!

 

[J&K]

nd I'm so relieved that he found the problem. It's a wonder it worked at all!

Wow Thanks for the update. Nice when the problem is found

 

[D&D]

UPDATE: When I first "lifted the lid" of the cabin to reveal the wiring plugs & sockets, relay, aircon ducting, blower, etc, there was much more dust on everything than I expected. Strange, because I've had the four air filters replaced regularly. Then I noticed the foam sealing strip which runs around the perimeter of the cabin frame had never been installed properly. My white lines show where the strip should be:

View attachment 3392594

Then yesterday when my experienced aircon & auto electrician mate was here, after checking for the correct pressures, we popped the lid again. He saw the leaking seal and all the dust and asked if I'd looked inside the ducting at all. I hadn't - with all the linkages and mechanical cables to operate various flaps and diverters, etc, it looked to be a job for someone above my pay grade. Like him!

So he removed the fan blower assembly in front of the evaporator, which revealed the problem:

View attachment 3392595

Some time later, after gently flushing it all off with water, and replacing the main relay which he suspected might have had bad contacts (it did, which a destructive tear-down revealed), he reassembled it all, and it works beautifully again.

So a very happy camper here, and I'm so relieved that he found the problem. It's a wonder it worked at all!

Thanks for bringing this full circle. This repair is one for the book. Since it was a mate, does that mean the repair bill was paid in beer?

 

[Oz_Kioti]

Thanks for bringing this full circle. This repair is one for the book. Since it was a mate, does that mean the repair bill was paid in beer?

Well, no - it was a paid job, although he is a good mate. We're both in the same home-brew club, so no need to "pay with beer" - we're both awash with that! However he recently split the scene from his previous small mum-and-dad employer, and decided to make it on his own. So his time is money and I very much respect that. I'm long retired, so time means nothing to me, but his situation is so different, and nice to know that I'm not at the mercy of outfits about which I know nothing.