QuestionWhen I turn my ac on, I hear a hissing sound coming from the passenger side under dash in housing that blower fan is mounted. With engine warmed up, both heater hoses entering this blower housing are hot. Outside air temp 74 degrees, air temp coming out vents is 90 degrees. Temp control knob is turned all the way to the coldest setting.
ac suction pressure is 30 psi. Is hissing sound from blower compartment a leaking vacuum line or a partially opened coolant to heater core valve, or something else?
AnswerTony,
The hissing you hear sounds to be a vacuum line. I say this because you say your low pressure is 30 (about where it should be) that tells me your compressor is operating. The only reason that It should blow hot when the compressor is running normally is your blend door is not opening.
Your blend door is what seperates your heat from the heater core and the cool from the A/C evaporator. Depending upon where you set the control panel it will either open the airflow through your heater core or evaporator, or both. Your door is opened by a vacuum being pulled on the actuator which in turn, closes the door.
Unless you can see the actuator from under the dash, or by pulling out your glove box (I haven't touched a santa fe, I do not know which is easier) I would recommend you taking it to a reputable shop and have them repair it. Simply because getting to the actuator can be a pain in the neck sometimes. However, if you can see it, it is a relatively simple fix. You will either have to put the hose back on the actuator nipple, or replace the hose itself (you may find it to be split)
Thank you for your question, I hope I was able to be of some assistance, if so please remember to rate this answer. If I can be of any help now or in the future, please do not hesitate to ask. Thanks again and good luck in everything.
