A/C not working in cold temps.

   / A/C not working in cold temps. #1  

kiotiken

Veteran Member
Joined
Aug 29, 2011
Messages
2,344
Location
Dunrobin, Ont
Tractor
2012 Kioti DK45 HST Cab
I use my A/C with heat to keep the cab fog free. Earlier this winter and now consistently during our latest little cold snap, the A/C will not come on. The first time it happened, I checked the fuse and it was fine and then after using the tractor for about 20 minutes (after it had warmed up for an initial 20 minutes), it all of a sudden came on. It's been the same story every subsequent time, push the button, nothing happens (the little light on the button doesn't even light up) but after some period of time, it kicks in. My dealer said he didn't know if that was normal and it had to warm up first but he would look at it. To me, that doesn't sound right at all and I don't remember anything similar from last winter. Does anybody know if there's some sensor that prevents the A/C from working for some period of time or until the engine has warmed to some temp? I always allow the engine temp to come up to normal range with the PTO engaged to help warm the oil before using the tractor.
 
   / A/C not working in cold temps. #2  
A/C in car/trucks wont come on below a certain temp to avoid icing.. I know in my Audi, it was 0c degrees and some cars are 4c.. The temp sensor on yours must be under the hood so when the engine bay heats up, it comes on.
 
   / A/C not working in cold temps. #3  
The sensor has to read above 5C before the AC will kick in. On my DK40 I turn the switch AC on, crank the heat on high and let the tractor warm up and by the time I get back to the tractor the AC is working.

Jason
 
   / A/C not working in cold temps.
  • Thread Starter
#4  
OK, thanks guys. Maybe it's just been really cold lately, but it's taken upwards of 40 minutes run time to come up to that temp including warm up.
 
   / A/C not working in cold temps. #5  
Sounds normal to me. Most cab units have an overhead evaporator and heating coil combined. Their is a temp sensor that keeps the evaporator from freezing up when the A/C is on. It turns off the compressor, prevents the evaporator from turning into a block of ice and not allowing air flow over the coils. In winter its sensing the cold untill the heater core warms it up enough to power the compressor. Are you running a block heater to keep the coolant warm? Fan on high will help speed the process.
 
   / A/C not working in cold temps. #6  
The light should still come on??
Mine does anyway, even when it is to cold for the compressor to cycle.
I need to warm my tractor up before I turn the temp knob up for the heater.
If I start the tractor when it is bitter cold, turn on the heat and walk away for 20 min it will barely be off cold.
If I leave the heat off, the coolant temp will come up to the middle in15 min or so,then if bring the revs up to 1500 or so turn then temp up and the guage will say between the dots.
If I drop it to idle with the fan cranked up, it will pull the gauge all the way back to cold after a few minutes at low idle.
So I try and get the coolant temp up first before turning the heat on, then run it to keep it up between the dots.

This is how it was the day I ran it at 0 F.
 
   / A/C not working in cold temps. #7  
The light on my AC switch doesn't light up until the sensor is warm and it takes a while for everything to get warm enough to make the AC kick in.

We've been having some rather cold weather recently and I find my tractor acting the same as yours. If I'm blowing snow, the temp gauge will be between the dots and I get lots of heat, but as soon as I unload the engine, it quickly cools off.

Jason
 
   / A/C not working in cold temps. #8  
My opinion that most tractors have oversized cooling systems, unlike cars that must warm up quickly for emissions to drop. I rarely see them run hot under normal conditions. As long as coolant levels within range and radiators not completely clogged. That said it just takes a long time to warm up as they are so efficient at getting rid of engine heat. You might try the old trick of cardboard or plywood in front of the radiator to block airflow until the engine coolant is up to temp. When the A/C comp is engaged you are actually cooling the evaporator the same time as hot water is trying to heat the evaporator. The refrigerant is still flowing through the evaporator and cooling the hot water until it gets warm enough to overcome the refrigerant ability to cool. So with A/C engaged and running you have a second radiator removing coolant heat in your overhead or dash depending where your evaporator is. If your system has a seperate heater core located in another area than your A/C evaporator than I apologize and none of this applies. My fan switch works independent of the A/C and I do not turn on the A/C while trying to heat the cab.
 
   / A/C not working in cold temps.
  • Thread Starter
#9  
My opinion that most tractors have oversized cooling systems, unlike cars that must warm up quickly for emissions to drop. I rarely see them run hot under normal conditions. As long as coolant levels within range and radiators not completely clogged. That said it just takes a long time to warm up as they are so efficient at getting rid of engine heat. You might try the old trick of cardboard or plywood in front of the radiator to block airflow until the engine coolant is up to temp. When the A/C comp is engaged you are actually cooling the evaporator the same time as hot water is trying to heat the evaporator. The refrigerant is still flowing through the evaporator and cooling the hot water until it gets warm enough to overcome the refrigerant ability to cool. So with A/C engaged and running you have a second radiator removing coolant heat in your overhead or dash depending where your evaporator is. If your system has a seperate heater core located in another area than your A/C evaporator than I apologize and none of this applies. My fan switch works independent of the A/C and I do not turn on the A/C while trying to heat the cab.

Another big difference is cars and trucks now use electrically driven fans as opposed to the old belt driven system that tractors still use. Until there's heat in the system, your car or truck isn't blowing cold air through the rad so it'll warm up a lot faster. It's no wonder it take the coolant a while to come up to temp when it's -30C outside and you're blowing that cold air through the rad.
 
   / A/C not working in cold temps. #10  
If the thermostat is working properly the radiator and fan should have very little effect. The main factor with Diesel engine warm-up is the amount of power produced. which is pretty small at idle. Gasoline engines, on the other hand, have to work to suck air past the throttle. Diesels don't have a throttle plate (there are rare exceptions) so the intake manifold is close to ambient pressure and the engine does minimal work on the intake stroke. The Russians have lots of cold weather experience and many of their Diesel vehicles include an oil heater and electric oil pump to lube the engine before attempting to start it. They also use compressed air for cold starts (injected on the power stroke) for many vehicles with an electric backup starter. I understand that it's best to warm up a Diesel with a light load (vs pure idle) after oil pressure is stabilized.
 

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