The thermostatic modulating valve in the inlet valve is stuck in one position, you could try to disassemble and get the piston and valve unstuck, but I would just put in a more modern valve so you could have the much more desirable cold rinses, keep in mind that if you are installing a newer style inlet valve you need to get one with a flow restrictor in the valve outlet so the timed fill will not overfill, it needs to restrict the fill to around 3 gallons per-minute.
John L.