A/C will not turn on

Tiny
CISCO4512
  • MEMBER
  • 2000 NISSAN MAXIMA
  • 3.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 240,000 MILES
Hey all, so the A/C is just blowing hot air. I was going to recharge it and noticed the clutch not engaging at all. Checked all fuses and relay first. All is good could not figure out why but if I take a piece of wire and jump it at the relay it works clutch engages blows cold air. Changed out relay but still the same. Any ideas?
Wednesday, September 4th, 2019 AT 4:06 PM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good evening.

I attached a wiring diagram for you to view. With the key on, verify there are 2 powers to the relay.

Roy
Images (Click to make bigger)
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 4:20 PM
Tiny
CISCO4512
  • MEMBER
  • 6 POSTS
I checked power I do have power at relay at 5 and 2 and nothing at 1 and 3.
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 5:04 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Okay, the ECM is what grounds the control side of the relay to engage the compressor.

There is a pressure switch on the little line for the Freon. It has 3 wires. Test for 5 volts to the red wire with the sensor disconnected.

Roy
Images (Click to make bigger)
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 5:19 PM
Tiny
CISCO4512
  • MEMBER
  • 6 POSTS
Okay, I just check the pressure switch I do have 5 volts at the red wire.
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 5:47 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Okay, is there another 5-volt wire as well?

Roy
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 5:51 PM
Tiny
CISCO4512
  • MEMBER
  • 6 POSTS
I double checked that just now and nothing on the other two.
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 5:58 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
The middle wire is the signal wire and should also have 5 volts. You may have a bad ECM.

Roy
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 6:10 PM
Tiny
CISCO4512
  • MEMBER
  • 6 POSTS
How do I diagnose the ECM to know for sure? And thanks for all your help, much appreciated.
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 6:39 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
The 5 volts comes from the ECM.

In my first response, I attached a wiring diagram. Follow the wire back to the ECM and see if there is power coming out at that pin.

Download the wiring diagram to your laptop and then enlarge it so you can see it better.

Roy
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 6:53 PM
Tiny
CISCO4512
  • MEMBER
  • 6 POSTS
Thank you.
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 6:55 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
You are welcome.

Roy
Was this
answer
helpful?
Yes
No
Wednesday, September 4th, 2019 AT 6:57 PM

Please login or register to post a reply.

Related Air Conditioner Recharge Content

Air Conditioner Recharge - Simple
VIDEO
Air Conditioner Recharge - Simple
Instructional repair video
Air Conditioner - Add Refrigerant
GUIDE
Air Conditioner - Add Refrigerant
In this guide we show you how to add refrigerant to your car's air conditioner system, simple and easy. Getting started, you will need a refrigerant kit that looks like this...
VIEW MORE