How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jared D Your Own Question
Jared D
Jared D, ASE Certified Technician
Category: Nissan
Satisfied Customers: 1804
Experience:  Shop Supervisor at County Fleet
Type Your Nissan Question Here...
Jared D is online now
A new question is answered every 9 seconds

AC stops blowing cold after 20 mins and has freon. Mechanic

Customer Question

AC stops blowing cold after 20 mins and has freon. Mechanic says it's the expansion valve but I'm not sure.
JA: How is the air flow? Have you checked the hoses?
Customer: Air flow slows afterwards also. air comes out cool but not cold,
JA: Tell me a bit more about what's going on so he can help you best.
Customer: shop says pressure is wrong on hoses also
JA: Are you hoping to fix this yourself?
Customer: No, I can throw 600 dollar fixes at it not knowing if this is really the issue
JA: OK! The Nissan Mechanic will help you with the diagnostics so you are sure to get this fixed right. Is there anything else the Nissan Mechanic should be aware of about your Nissan?
Customer: condenser is good
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Nissan Mechanic about your situation and then connect you two.
Customer: no leakes in system either
Submitted: 1 year ago.
Category: Nissan
Expert:  Jared D replied 1 year ago.


What year and model is your nissan?

Customer: replied 1 year ago.
Expert:  Jared D replied 1 year ago.

Do you know the model? Pathfinder, altima, sentra, tundra...?

Customer: replied 1 year ago.
2006 Xterra off road
Expert:  Jared D replied 1 year ago.

The xterra has been known to have expansion valve problems. What normally happens is they get stuck in one position. The AC then blows cold constantly until the evaporator freezes up and then air can no longer flow through it. This explains why it not only stops blowing cold, but it also stops blowing very hard. If you had mentioned that it just gets warm then I would recommend checking compressor function, freon levels, etc, but if the actual flow of air decreases then it's almost certain that the evaporator is freezing. The only thing to cause that is a bad expansion valve.

Expert:  Jared D replied 1 year ago.

It is a major job since replacement requires removal of the dash.

If you turn the AC to heat for about 5 minutes (when it is no longer blowing cold) and then back to AC will it blow cold again for a few minutes?

Expert:  Jared D replied 1 year ago.

Please let me know if you need additional information.

Customer: replied 1 year ago.
THE EXPANSION VALVE WAS CHANGED AND IT STILL DOES THE SAME THING. After 20 mins air is not longer cold and restricted. If I turn off the ac for about 5/10 minutes ac will work again for a while. I can't keep throwing 600 dollar fixes at this. Any advice?
Expert:  Jared D replied 1 year ago.

Has anyone taken a look at the AC air intake sensor circuit? If the air intake sensor is faulty it could be telling the AC control unit that the air coming into the evaporator and the evaporator is too hot and then it keeps the AC compressor on for longer than it should causing the evaporator to freeze. It's not terribly common to go bad, but it's all that is left that could be malfunctioning and cause a system freeze up like you are describing.

Expert:  Jared D replied 1 year ago.

Here is a description of the sensor from nissan.

Customer: replied 1 year ago.
How much will that usually cost to check and possibly repalce? What about the Thermistor?
Expert:  Jared D replied 1 year ago.

We might be talking about the same part as I can't find a separate listing for the thermistor and the intake sensor is technically a thermistor. It lists as .3 hours or labor, so about $45 in labor, the part doesn't list a price in my catalog so it is likely only available from the dealer.

Customer: replied 1 year ago.
Where is this located?
Expert:  Jared D replied 1 year ago.

Right behind the glove box.

Customer: replied 1 year ago.
Do I have to have my dash taken off again?
Expert:  Jared D replied 1 year ago.

No, just the trim panel by the glove box. This is much more simple.

Customer: replied 1 year ago.
Thank you. I will let you know how this goes.
Expert:  Jared D replied 1 year ago.

I would have imagined that the mechanic would have checked that part first. That's why I asked if the AC will work again after turning to heat for about 5 minutes back on the 25th. If I had known that it would then I would have suggested checking this sensor.

Customer: replied 1 year ago.
No the guys did not check it. They just went by pressure in the lines. I did not take this to Nissan, they did not have openings for some time. I guess I'm learning a lesson. I will be very upset if this was the issue. They assured me it was the expansion valve, said it was stuck open. I have the off part but not sure how to see if they are coorect. Idiots had my whole dash off. You would think they would.....
Expert:  Jared D replied 1 year ago.

I have to say that I was leaning toward stuck expansion valve as well, but only on the assumption that the ambient temp reading had been checked by the shop. They should have pulled it up on a scan tool to see if the temp reading was stuck.

Expert:  Jared D replied 1 year ago.

Please don't forget to rate.

Let me know if you need additional information.