I have a New Holland 3630. While I was using the rear blade for snow removal today, the rear power lift stopped lifting the blade. Everything else on the tractor works normally, only the rear lift does not raise. The elevator will lower the blade and when I used a come a long to raise the blade, the elevator will keep the blade in the raised position. The up / down lever works freely. PTO works, loader works well, rear remote hydraulic outlets are pressurized.
I’m not sure ice itself is your problem, but cold temperatures in general may be a factor. Ice internally often affects hydraulic oil flow in the pump more than anything else. If your other functions are working, then the system must be moving oil. The flow into and out of the lift cylinder is controlled by the lift valve. This unit is installed in the front of the lift housing, roughly under the seat. It has a stem and knob that protrudes towards the front of the tractor and controls the rate of fall of the lift arms. This statement is for identification purposes only, not that it gets into the problem.
The point is that this valve body contains multiple spools, springs, and other elements that move back and forth under spring pressure, hydraulic pressure, or mechanical stress from the control levers and / or the movement of the valve. shaft of rocks. These are different metals, with slightly different expansion / contraction rates. If we add to this the machining tolerances used during manufacturing, the results can lead to what you are experiencing.
You could try adding some heat to the lift unit in the control valve area for a while, perhaps with one or two lamps strategically placed and covered with something to help retain heat.
That might be enough to make a difference.
