A/C not working in cold temps.

[SSdoxie]

Ken, Looking at the cab schematic for Bobcat (same cab) the voltage supply to the AC switch comes from the fuse, through the Hi/Low pressure switch. So if it is cold enough to reduce Freon pressure below minimum the switch won't receive power to light the indicator light. Or if Freon is low, needs a little re-charge.
The cab Evaporator is first inline of air flow from the blower fan, so cab air will have to be warm enough to blow warm air to the evaporator thermostat before compressor clutch engages. Not sure about the controls regarding internal recirculation vs. external air intake, but if it can be set to internal recirculate cab air the evaporator will warm up faster.

 

[Jose G]

you should not let the tractor sit on idle for a long period, let the throttle at 1k rpm if you have to.
it could wash the cylinder because of diesel burning poorly. does your oil smell diesel?
when I start my tractor, I normally let it idle for 5 mins at 0 throttle, then crank it up at 1k rpm to finish the warming process

 

[Jesse masterson]

My Dk 45 idles at 1 k. Always wondered of that was high.

 

[Looking4new]

My CK27 also idles at 1K. After the oil pressure is up I bump the throttle to 1200 and let her idle for 20 minutes or so before I get to work. I work (blow snow) right from the get go.

 

[irvingj]

Ken, I believe SSdoxie has it: I would also guess that there's a low-pressure shut-off-- many refrigeration systems have this.

Ambient temp around the evaporator coil would have to rise (tractor warms up) before internal refrigerant pressure would climb, LP would switch "ON" and allow compressor to run. The idea is to prevent the compressor from coming on (and possibly icing up the evaporator and/or sucking in air) if there's a leak and the refrigerant is low.

Also, keep in mind that if the evaporator does get iced up, refrigerant won't evaporate and there's a good chance of a slug of liquid getting back to the compressor…definitely not good. irvingj

 

[kiotiken]

Ken, Looking at the cab schematic for Bobcat (same cab) the voltage supply to the AC switch comes from the fuse, through the Hi/Low pressure switch. So if it is cold enough to reduce Freon pressure below minimum the switch won't receive power to light the indicator light. Or if Freon is low, needs a little re-charge.
The cab Evaporator is first inline of air flow from the blower fan, so cab air will have to be warm enough to blow warm air to the evaporator thermostat before compressor clutch engages. Not sure about the controls regarding internal recirculation vs. external air intake, but if it can be set to internal recirculate cab air the evaporator will warm up faster.

Ken, I believe SSdoxie has it: I would also guess that there's a low-pressure shut-off-- many refrigeration systems have this.

Thanks guys and sorry for the delayed response, just getting back into the swing of things after the holidays. I was out working with the tractor again last night. The temperature must have been colder than -30C, but I didn't check (who cares at that point). I fired up the tractor, waited a few minutes and idled it up to about 1200 RPM and switched on the PTO to get it warmed up. I also turned the cab air off to allow the heat to stay in the engine. After 20 minutes (at least) I came back out to the tractor and it was in the normal temp range so I turn on the heat, increase RPM up to about 1800 and slowly moved out of the shed. I then work the loader up and down a dozen times and scoop and dump the bucket as well, before going up to 2200-2400 RPM. It takes a lot to get everything moving properly at those temps. Anyway after about 10 minutes, my hat and gloves were off and the cab got quite warm. I worked for about 45 minutes total and then went to go put it away again. Right before killing the engine, I thought I'd try the A/C to see if it was working and sure enough, it was not.

So thank you for the explanation and checking the schematics for me. I will address it with my dealer in the spring before the warranty is up (I wouldn't let him float the tractor to his shop in the winter for anything be a total break down, there's way to much road salt). I'm thinking there must be a leak and the Freon level is low because there's no way that it should take that long to warm up. As cold as it was last night, the cab was toasty warm (and I'm assuming the ceiling space as well) and the engine was working hard and should have warmed everything else up in that time. I don't remember ever having this issue last year so something has changed.