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2011 Sierra 6.2L AC short cycling

Not pressure or switch related

2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 11 2019, 3:57pm

Vehicle in question is a 2011 GMC Sierra Denali AWD with 6.2L Automatic 185K mIles

A/C is short cycling. I thought it was an issue with the low pressure switch so I replaced it with a A/C Delco OEM one. Still short cycles.

After that I thought that maybe the system was indeed low. So I went to my local parts store and rented their gauges and vacuum pump set.

1. I properly recovered the refrigerant ( cough cough ), pulled vacuum on the system for 30 mins, let it sit for another 30 mins with no change in losing vacuum.

2. I manually jumped the A/C relay and added 25.6 Oz of R134A to the system. System pressure at 85 Degrees was 38 PSI low side and 190 On the high side. Air coming out of the vents at a cool 43 degrees.

Put the relay back in but now it does the same thing , short cycling. On for 2 seconds and off for about 10 to 15 seconds. No cool air coming out of the vents. what can this be?
Original Poster
atxjax
Firing on 3 cylinders [L1]
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Re: 2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 08 2020, 11:04am

bumping this and its old. I still have not found a fix to this
Original Poster
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Firing on 3 cylinders [L1]
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Re: 2011 Sierra 6.2L AC short cycling

Postby B52Bombardier1 » Aug 08 2020, 11:56am

I'm thinking clogged system, blockage somewhere. Your pressure switches are doing their job. With a blockage, the pressures are going high or low somewhere.

Has anybody ever used refrigerant with a sealant in this vehicle . . . . ??? Most of the professional shops don't recommend it.

Rick
1970 Chevy El Camino 5.3 liter LM7 Engine and 4L60E Transmission
B52Bombardier1
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Re: 2011 Sierra 6.2L AC short cycling

Postby 660catman » Aug 08 2020, 12:23pm

Possible plugged orifice tube. Another forum member had issue with his 2013 exactly like my 2013. Here’s a pic of his which is what mine looked like.
Image


2013 Silverado LT CC 1500 Z71 5.3 4WD 3:42’s all stock
2013 Silverado 1500 Z71 CC 5.3 4WD 3:42's and all stock
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Re: 2011 Sierra 6.2L AC short cycling

Postby TennMan » Aug 08 2020, 1:31pm

atxjax wrote:bumping this and its old. I still have not found a fix to this

Start by replacing he AC relay with a new one to rule that out. Then put a jumper across the low pressure switch connector to rule that out too. Yeah, I know it's a new switch but don't take for granted it is good because it's new. Your truck probably has the climate control that regulates the temperature. In that case you could have a bad low TEMP sensor causing the compressor to cycle prematurely.
Ronnie
2001 Sierra 1500 SL - Storm Gray / Graphite interior- ~147K
Just your basic short bed truck. 4.3 V6 -- Automatic -- 2WD

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Re: 2011 Sierra 6.2L AC short cycling

Postby Larry-Cleveland » Aug 09 2020, 4:20pm

I think if you test the voltage and find out what component is cutting the circuit it will give you a better clue as to where the problem is. I would start at the relay feed and work your way forward.
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Re: 2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 16 2020, 7:59pm

660catman wrote:Possible plugged orifice tube. Another forum member had issue with his 2013 exactly like my 2013. Here’s a pic of his which is what mine looked like.
Image


2013 Silverado LT CC 1500 Z71 5.3 4WD 3:42’s all stock



Hmmm......I was under the impression that these trucks have expansion valves.
Original Poster
atxjax
Firing on 3 cylinders [L1]
Firing on 3 cylinders [L1]
Posts: 33
Topics: 6
Joined: Aug 11 2019, 3:51pm
Years of membership: 1 year of membership
Location: Pflugerville, TX USA
Year: 2007
Make/Model: GMC Sierra
Variant: SLE
Extra Info: 53.L with 4L60E
Group Membership:
Registered users

Re: 2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 16 2020, 8:00pm

TennMan wrote:
atxjax wrote:bumping this and its old. I still have not found a fix to this

Start by replacing he AC relay with a new one to rule that out. Then put a jumper across the low pressure switch connector to rule that out too. Yeah, I know it's a new switch but don't take for granted it is good because it's new. Your truck probably has the climate control that regulates the temperature. In that case you could have a bad low TEMP sensor causing the compressor to cycle prematurely.



Problem I ran into on the switch is that it's a three wire. Dont want to jack anything up. We did swap out relay and has same issue. Yes, this truck has the 2 zone with temp control
Original Poster
atxjax
Firing on 3 cylinders [L1]
Firing on 3 cylinders [L1]
Posts: 33
Topics: 6
Joined: Aug 11 2019, 3:51pm
Years of membership: 1 year of membership
Location: Pflugerville, TX USA
Year: 2007
Make/Model: GMC Sierra
Variant: SLE
Extra Info: 53.L with 4L60E
Group Membership:
Registered users

Re: 2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 16 2020, 8:02pm

Larry-Cleveland wrote:I think if you test the voltage and find out what component is cutting the circuit it will give you a better clue as to where the problem is. I would start at the relay feed and work your way forward.



A schematic would be great. I cant find one though.
Original Poster
atxjax
Firing on 3 cylinders [L1]
Firing on 3 cylinders [L1]
Posts: 33
Topics: 6
Joined: Aug 11 2019, 3:51pm
Years of membership: 1 year of membership
Location: Pflugerville, TX USA
Year: 2007
Make/Model: GMC Sierra
Variant: SLE
Extra Info: 53.L with 4L60E
Group Membership:
Registered users

Re: 2011 Sierra 6.2L AC short cycling

Postby atxjax [OP] » Aug 16 2020, 8:07pm

B52Bombardier1 wrote:I'm thinking clogged system, blockage somewhere. Your pressure switches are doing their job. With a blockage, the pressures are going high or low somewhere.

Has anybody ever used refrigerant with a sealant in this vehicle . . . . ??? Most of the professional shops don't recommend it.

Rick



No sealant that I know of since the truck was bought new. Guess I need to crack it open and look at t he orifice.
Original Poster
atxjax
Firing on 3 cylinders [L1]
Firing on 3 cylinders [L1]
Posts: 33
Topics: 6
Joined: Aug 11 2019, 3:51pm
Years of membership: 1 year of membership
Location: Pflugerville, TX USA
Year: 2007
Make/Model: GMC Sierra
Variant: SLE
Extra Info: 53.L with 4L60E
Group Membership:
Registered users

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