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A/C not working after replacing the condensor

Tiny
TOM81
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 232,433 MILES
My old AC unit was leaking so I had to replace the compressor with a new one. Once I have the new compressor installed and charged it work but it blew the valve or the sensor out of the back of the compressor. I Replaced that snap ring that holds a sensor in. Recharge the system and the in cab control unit quit working the AC light would not turn on nor would the compressor kick in I put a different control unit in and it worked for about thirty seconds then quit. I am not sure where to go from there The compressor will run if it is bypassed or jumped by the relay.
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Sunday, June 17th, 2018 AT 5:35 AM

21 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

The control head sends a signal to the high pressure switch which is the one that popped out. The Freon may have damaged either the wiring or the switch itself causing the control head to fail.

Check the switch for voltage with the key on. It should have voltage. I attached a wiring diagram for you to view.

Roy
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Sunday, June 17th, 2018 AT 10:41 AM
Tiny
TOM81
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That is the sensor/switch on the back if the AC compressor? I will look for voltage there, since the head unit is bad there will be none correct?
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Sunday, June 17th, 2018 AT 12:26 PM
Tiny
ASEMASTER6371
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Check the voltage first, it does come from the control head but you also need to check the wiring to be sure it is not wiring.

If you have no voltage at the switch, go back to the control head and verify the voltage the connector.

Roy
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Sunday, June 17th, 2018 AT 12:28 PM
Tiny
TOM81
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I will try them steps first, that sensor did have a small crack in it but I never figured that would have made it not work since it worked on the old compressor. I will keep you posted! Thanks
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Sunday, June 17th, 2018 AT 12:31 PM
Tiny
ASEMASTER6371
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You are welcome.

Keep us updated and let us know if you need more help.

Roy
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Sunday, June 17th, 2018 AT 12:34 PM
Tiny
TOM81
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I do have power on dark brown wire that connects to head unit, but not on the sensor side.
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Sunday, June 17th, 2018 AT 12:45 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay.

Dark brown and dark green are the powers to the control head.

Do you have power at the high pressure switch?

The light green wire is the output for the high pressure switch.

Roy
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Sunday, June 17th, 2018 AT 12:49 PM
Tiny
TOM81
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I do not not have power at the light green white but too the dark brown wire at the head unit, and 1.35 volt or wire in switch.
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Sunday, June 17th, 2018 AT 12:58 PM
Tiny
ASEMASTER6371
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What about the dark green wire? That is main power and must have power?

If you have power then the control head is the issue but may have been burned out from the light green wire shorting to ground.

Roy
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Sunday, June 17th, 2018 AT 1:01 PM
Tiny
TOM81
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The dark green wire has no power.
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Sunday, June 17th, 2018 AT 1:04 PM
Tiny
TOM81
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I jumped the dark brown wire to the dark green wire and then there was power to the switch on compressor, when then two are jumped the blend actuator under dash works. Think I am going to have to take to a shop.
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Sunday, June 17th, 2018 AT 1:14 PM
Tiny
ASEMASTER6371
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Yep, you have a wiring issue. Both of those wires come from the same fuse.

It is a harness issue.

Good job doing the testing. At least you found the exact cause.

Roy
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Sunday, June 17th, 2018 AT 1:28 PM
Tiny
TOM81
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Thanks for your help!
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Sunday, June 17th, 2018 AT 1:39 PM
Tiny
ASEMASTER6371
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Never a problem.

Glad to help.
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Sunday, June 17th, 2018 AT 1:46 PM
Tiny
TOM81
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Roy, I think the cause of this issue is the blend door actuator. I have it unplugged and it works great. I plug it in and takes out the head unit! What does that have to do with the AC if I may ask! Thanks
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Thursday, June 21st, 2018 AT 4:19 PM
Tiny
ASEMASTER6371
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All the commands for the blend door actuator come from the control head.

Get another actuator and just plug it in before installing it and see if it all works.

It may be pulling down the voltage.

Roy
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Thursday, June 21st, 2018 AT 4:33 PM
Tiny
TOM81
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What is cell 63? Or schematic of it?
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Thursday, June 21st, 2018 AT 6:44 PM
Tiny
ASEMASTER6371
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Cell 63? Please explain.

Roy
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Friday, June 22nd, 2018 AT 3:56 AM
Tiny
TOM81
  • MEMBER
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Inside the control head. There is a compressor logic, what is that for is that a relay or a resistor?
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Friday, June 22nd, 2018 AT 4:01 AM
Tiny
ASEMASTER6371
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I do not have a break down of the control head. I never mess with that. If it is bad, then I replace it.

Roy
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Friday, June 22nd, 2018 AT 4:16 AM

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