A/C compressor has no power

Tiny
EQUILIZER
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • 4.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 210,000 MILES
Hi, I have been having trouble trying to find out what is going on with my A/C. I just recently changed the quick connect on the anti freeze line for the heater. And doing so when I took off from my house my A/C worked fine. But I got a burnt wire smell in my A/C and when I stopped to take a look I saw nothing. When I started my truck up again I was not getting as cold of A/C that I usually get. So I took the truck back home and I saw my compressor was powering on and off still and it was cooling my Freon line. But the next day on my way to work I got that wire smell again. I am not sure if it was a wire or a relay but something burned out because now my compressor does not engage and I was told that I have no power to the compressor either anymore.
Wednesday, May 23rd, 2018 AT 4:22 PM

15 Replies

Tiny
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  • MECHANIC
  • 52,796 POSTS
Good morning.

The first thing I would check is the pressure in the AC system. Anything below 20 lbs will not allow the compressor to engage.

As far as the smell, it may be from spilled coolant on a hot surface.

Roy

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/air-conditioner-leak-detection
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Thursday, May 24th, 2018 AT 3:47 AM
Tiny
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Well I bypassed the A/C to see if the compressor started up and nothing. So I checked the wiring and the green wire that goes to the compressor does not have any power to it.
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Thursday, May 24th, 2018 AT 12:34 PM
Tiny
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Okay, the first thing you need to check is for power to the compressor relay. It is in the fuse box under the hood. Remove the relay and test for two powers with the key on.

Roy
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Thursday, May 24th, 2018 AT 12:40 PM
Tiny
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Okay, so just remove the compressor relay start up the truck and test the connections for power.
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Thursday, May 24th, 2018 AT 12:43 PM
Tiny
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No need to start. Just turn the key on and use a test light or volt meter.

Roy
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Thursday, May 24th, 2018 AT 12:45 PM
Tiny
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Okay, I will give it a try when I get out of work. If there is no power what could it be?
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Thursday, May 24th, 2018 AT 12:49 PM
Tiny
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If you look at the diagram, there are two fuses that need to be checked for power on both sides.

Roy
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Thursday, May 24th, 2018 AT 12:50 PM
Tiny
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Okay the IGN-E fuse is good and so is the A/C COMP fuse, but on the compressor relay 87 and 85 are not lighting up.
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Thursday, May 24th, 2018 AT 3:27 PM
Tiny
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Need power to 30.

Did you verify power across the fuses? Use a test light or voltmeter.

Roy
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Thursday, May 24th, 2018 AT 3:54 PM
Tiny
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I tested the fuses and they lit up. What do you mean by across?
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Thursday, May 24th, 2018 AT 4:02 PM
Tiny
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Check both sides of the fuse. Need to verify power through the fuse.

If there is power on both sides, then you have a wiring issue between the fuse block and the relay. The powers for the relay come from the fuse box.

Roy
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Thursday, May 24th, 2018 AT 4:04 PM
Tiny
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On those two fuses I tested both sides turned on.
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Thursday, May 24th, 2018 AT 4:08 PM
Tiny
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Okay, if you have no powers to the relay, then the wiring is open between the fuse box and the relay.

You will need to inspect the harness for any damage or burning.

Roy
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Thursday, May 24th, 2018 AT 4:12 PM
Tiny
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How do you take off the fuse box?
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Thursday, May 24th, 2018 AT 4:17 PM
Tiny
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Procedure below and picture attached.

Roy

REMOVAL PROCEDURE
1. Disconnect the negative battery cable.

ImageZoom/Print

2. Remove the left fender upper brace.

ImageZoom/Print

3. Remove the electrical center brace cover assemble by lifting the cover (3) outwards to clear the tabs.
4. Remove all fuses and relays.

ImageZoom/Print

5. Push on the tab (3) so that the electrical center can be rotated on the studs located at (2).
6. Remove all connectors by removing the bolt (1) for each connector.
7. Disconnect all connectors from the electrical center block.

ImageZoom/Print

8. Push on the tabs (2) in order to lift the electrical center (1) out of the housing.

ImageZoom/Print

9. To replace the engine electrical center bracket remove the 4 retaining bolts (1).
10. Remove the engine electrical center bracket assembly from the fender.
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Thursday, May 24th, 2018 AT 4:23 PM

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