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Dan
Dan, ASE Certified Technician
Category: Ford
Satisfied Customers: 1568
Experience:  Auto Technician
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I have a hissing sound coming from the rear ac. Comes and

Customer Question

I have a hissing sound coming from the rear ac. Comes and goes it is a 2023 Expedition
JA: Where exactly do you think the noise is coming from? And how long has this been going on?
Customer: Have not been able to pinpoint but it is in the rear. couple of days
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes have not done anything yet
JA: Anything else you think the mechanic should know?
Customer: nope
Submitted: 6 months ago.
Category: Ford
Expert:  Dan replied 6 months ago.

Hello my name is***** am an ASE Master Technician and I am glad to help you out with your question.

Expert:  Dan replied 6 months ago.

Does the hissing sound happen when the rear blower is on?

Customer: replied 6 months ago.
Customer: replied 6 months ago.
It would come and go at first but now it is whenever the AC is on
Expert:  Dan replied 6 months ago.

You're hearing refrigerant flow through the orifice at the rear evaporator core. It echoes through the overhead duct work, and is rythmic with the cycling of the compressor. You'll hear the same "hissing" noise from every Expy/Navi with rear A/C. It's more pronounced when the vehicle is a bit low on refrigerant.

Customer: replied 6 months ago.
but only the rear AC it is not making that noise when just the front ac is on
Customer: replied 6 months ago.
ok thank you very much
Expert:  Dan replied 6 months ago.

You could have a slight leak and the refrigerant is slightly low, this could cause a hissing sound. I would say evac and recharge the system adding leak detection dye and drive it for a while, then use a uv light to find the leak.

Expert:  Dan replied 6 months ago.

Replace the leaking part and recharge, and the hissing noise will go away.

Customer: replied 6 months ago.
Ok thanks
Expert:  Dan replied 6 months ago.

Please reply to this if you need more help and we can continue this conversation. If you are satisfied with my service, please rate at the top of the screen. Rating does not close out your question. Remember, sometimes it is difficult to completely diagnose your vehicle without being there, but I will try to give you the best answer I can. If I am not giving you 5 star service, please let me know what I missed.

Thanks,

Dan

ASE Master Technician

Customer: replied 6 months ago.
Ok I will do that thanks
Expert:  Dan replied 6 months ago.

Thank you

Expert:  Dan replied 6 months ago.

Hello again Dan here,

I am contacting you because the post has not been closed or rated.

This question is coming up on 7 days which means it will close.

You have already paid to get this question answered, but you have not rated.

Let me help some more. Is there anything else I can help you with?

If I did not give you 5 star service, please let me know what I missed.

I do not get compensated for my time and resources unless you rate me.

Thanks