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Dan, ASE Certified Technician
Category: Ford
Satisfied Customers: 1687
Experience:  Auto Technician
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2010 mercury milan, the AC is not kicking in, it starts

Customer Question

2010 mercury milan , the AC is not kicking in , it starts working after couple of hrs. Any idea ?
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: Yes, I've checked. Everything ok.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I replaced the evap. Sensor,
JA: Anything else you think the mechanic should know?
Customer: I thought the relay in thre fuse box is the problem, because if I bypass it seems to be ok
Submitted: 1 year ago.
Category: Ford
Expert:  Dan replied 1 year ago.

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

Expert:  Dan replied 1 year ago.

You need to get a code scan of the hvac module. Also check the Freon pressures with a set of gauges. A low pressure switch will cause the compressor to disengage as well. Also a low charge of Freon will prevent the compressor from engaging.

Expert:  Dan replied 1 year ago.

Would you like a wiring diagram of the ac system of your truck?

Customer: replied 1 year ago.
I don't have the proper equipment to do that. I recharged the system with the right amount of freon.
Customer: replied 1 year ago.
It started working now, after 30 min of engine idling . Sometimes it takes hours , sometimes less
Expert:  Dan replied 1 year ago.

The computer controls the relay. Could be a wiring connection problem as well.

I can send you a wiring diagram if you like.

Customer: replied 1 year ago.
Ok,I hope that will help! Send me please the diagram
Expert:  Dan replied 1 year ago.


Expert:  Dan replied 1 year ago.

Do you still need help?

Customer: replied 1 year ago.
i couldnt figure it out.
For some reason if the pressure in hi circuit goes under 125 psi the compressor is not kicking in.
If I bypass the relay and have the compressor working and the pressure goes over 125-150 everything works ok
Customer: replied 1 year ago.
When is working the readings are:
Low pressure gauge:25-30
High .........................:200-225
Expert:  Dan replied 1 year ago.

You could have a compressor problem as well. This would cause your pressure to drop. Also check for expansion valve being stuck. Could have a restriction in the system as well.

Expert:  Dan replied 1 year ago.

If you accept the premium service I can send you a pdf diagram of the ac circuit.

Expert:  Dan replied 1 year 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.


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