If the evaporator pressure does not change when heat is added or removed from the thermostatic expansion valve bulb the problem may be?

If the evaporator pressure does not change when heat is added or removed from the thermostatic expansion valve bulb, the problem may be due to a malfunctioning thermostatic expansion valve itself, which could be stuck or blocked. Additionally, issues such as low refrigerant levels or a refrigerant leak can also prevent pressure changes. Lastly, a faulty bulb sensing element or improper bulb placement may hinder the valve's ability to respond to temperature changes effectively.