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Barry Sergeant
Barry Sergeant,
Category: Honda
Satisfied Customers: 26
Experience:  General Manager at All Things Automotive LLC
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Ac not working, but if I ground out the blue/ wire at the

Customer Question

ac not working, but if I ground out the blue/white wire at the pressure switch the fan runs and compressor runs
JA: Have you checked the Freon level?
Customer: yes it is good
JA: What is the model/year of your Honda?
Customer: 2001
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: replaced inside fuse micu because brake light was on and thought it might be the reason ac not coming on. everything seems to be ok except ac
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 5 months ago.
Category: Honda
Expert:  Barry Sergeant replied 5 months ago.

Hi, this is Barry and I would be happy to help. What model is your 2001 Honda?

Customer: replied 5 months ago.
2001 Honda civic lx
Expert:  Barry Sergeant replied 5 months ago.

Ok. Can you tell me what the outside temperature is where you are and the low side pressure reading with the AC off?

Customer: replied 5 months ago.
Its about 65 temp and low side about 80psi
Customer: replied 5 months ago.
when I ground blue white wire at pressure switch everything works and it puts out cold air inside vehicle
Expert:  Barry Sergeant replied 5 months ago.

Ok. With the AC turned on there should be ground on the blue wire going to the ac pressure switch. Does it have ground?

Expert:  Barry Sergeant replied 5 months ago.

Also what is the high side pressure with the ac off?

Customer: replied 5 months ago.
it is about 70 also
Expert:  Barry Sergeant replied 5 months ago.

Ok. That should be about right. The pressure switch supplies a ground signal from the blue wire to the blue/white wire when the pressures are correct. If they are high or low it disconnects the ground signal. So let's check and make sure you have a ground on the blue wire. If so I suspect you have a bad pressure switch.

Customer: replied 5 months ago.
no ground on blue wire
Expert:  Barry Sergeant replied 5 months ago.

Ok. That wire goes to the HVAC control module. It is in connector A position 4. I would check the continuity of that wire from the control module to the pressure switch. In the same connector on pin 13 should be a black wire it need to have ground.

Customer: replied 5 months ago.
shows continuity
Expert:  Barry Sergeant replied 5 months ago.

Ok. Does it have a ground on the black wire pin #13?

Customer: replied 5 months ago.
it has ground
Expert:  Barry Sergeant replied 5 months ago.

It appears that your problem is in the HVAC control panel. As it is what creates the ground for the pressure switch circuit. With no ground coming from the control the ecm sees it as the same as the the pressure switch cutting off.

Customer: replied 5 months ago.
Yea I would have to agree, thanks for the help
Expert:  Barry Sergeant replied 5 months ago.

No Problem.

Expert:  Barry Sergeant replied 5 months ago.

Just let me know if you need anything else.