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| [GMCnet] A/C compressor not engaging [message #174207] |
Thu, 21 June 2012 14:09  |
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My air conditioner compressor is not engaging. Following the procedure in the maintenance manual I shorted across the terminals on the pressure switch connector and the clutch engages. Per the manual this indicates that the pressure in the line is too low or the switch is defective.
Now my questions:
I'm using DuraCool I'm assuming that the pressure should be 20 -25 psi with the gauge connected to Gauge connection 1 ( see photo http://www.gmcmhphotos.com/photos/misc-gmc-photos/p44570-air-conditioning-clutch-not-functioning.html ). Is my assumption correct?
If the pressure is OK and I need to replace the pressure switch can I remove & replace the switch without opening the line and loosing the DuraCool?
Any comments/suggestions will be appreciated.
Bill Brown
Coshocton OH
'77 Buckeye Cruiser
Change is certain, progress is not
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Bill Brown - '77 Buckeye Cruiser
Coshocton OH
carguybill@sbcglobal.net
[Updated on: Thu, 21 June 2012 14:14] Report message to a moderator |
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| Re: [GMCnet] A/C compressor noit engaging [message #174215 is a reply to message #174214] |
Thu, 21 June 2012 14:54  |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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yah
but since he was on the wrong connection, I figure it will be ok
when he gets it right
gene
On Thu, Jun 21, 2012 at 12:52 PM, Emery Stora <emerystora@mac.com> wrote:
>
>
> On Jun 21, 2012, at 1:46 PM, gene Fisher <mr.erfisher@gmail.com> wrote:
> >
> > then the pressure sw will work, (I have not seen a bad one yet)
> >
> > gene
> >
> Then I guess I never told you about the one I had to replace.
>
> Like everything else, then can go bad.
>
> Emery Stora
> >
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--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] A/C compressor not engaging [message #174216 is a reply to message #174207] |
Thu, 21 June 2012 15:07 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Bill: in my opinion 20-25 lb will not kick the switch. It should be holding about 80-95 equallized on both sides with compressor not running.
I`m thinkin you are low on duracool.
| carguy wrote on Thu, 21 June 2012 15:09 |
My air conditioner compressor is not engaging. Following the procedure in the maintenance manual I shorted across the terminals on the pressure switch connector and the clutch engages. Per the manual this indicates that the pressure in the line is too low or the switch is defective.
Now my questions:
I'm using DuraCool I'm assuming that the pressure should be 20 -25 psi with the gauge connected to Gauge connection 1 ( see photo http://www.gmcmhphotos.com/photos/misc-gmc-photos/p44570-air-conditioning-clutch-not-functioning.html ). Is my assumption correct?
If the pressure is OK and I need to replace the pressure switch can I remove & replace the switch without opening the line and loosing the DuraCool?
Any comments/suggestions will be appreciated.
Bill Brown
Coshocton OH
'77 Buckeye Cruiser
Change is certain, progress is not
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] A/C compressor not engaging [message #174219 is a reply to message #174218] |
Thu, 21 June 2012 16:08 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Yes sir agreed. I was just saying just sitting there with the gauges on and the engine not running it should have more than 25 lb. Doesn`t it usually have bout the same pressure that is in the can?
It should be 20-25 on the low side with compressor running at 1500 rpm and air blowing on grill. But turned off and given time to equellize it should be 80-90 on either side.
| emerystora wrote on Thu, 21 June 2012 16:45 |
Chuck
I have found that, on a completely empty and evacuated system, you can put in just one can of Duracool and that will give enough pressure to allow the pressure switch to engage the clutch. You can then start the engine and the air conditioner and put in about two more cans of Duracool and it will be just about the right charge. With moderate ambient temperatures that should give about 20 psi at 1500 rpm. At higher ambient temperatures, say 90 deg and up it will likely give pressure closer to 25 psi at 1500 rpm.
Emery Stora
On Jun 21, 2012, at 2:07 PM, Charles Boyd <covered-wagon@comcast.net> wrote:
>
>
> Bill: in my opinion 20-25 lb will not kick the switch. It should be holding about 80-95 equallized on both sides with compressor not running.
> I`m thinkin you are low on duracool.
>
>
>
> carguy wrote on Thu, 21 June 2012 15:09
>> My air conditioner compressor is not engaging. Following the procedure in the maintenance manual I shorted across the terminals on the pressure switch connector and the clutch engages. Per the manual this indicates that the pressure in the line is too low or the switch is defective.
>>
>> Now my questions:
>> I'm using DuraCool I'm assuming that the pressure should be 20 -25 psi with the gauge connected to Gauge connection 1 ( see photo http://www.gmcmhphotos.com/photos/misc-gmc-photos/p44570-air-conditioning-clutch-not-functioning.html ). Is my assumption correct?
>>
>> If the pressure is OK and I need to replace the pressure switch can I remove & replace the switch without opening the line and loosing the DuraCool?
>>
>> Any comments/suggestions will be appreciated.
>>
>> Bill Brown
>> Coshocton OH
>> '77 Buckeye Cruiser
>> Change is certain, progress is not
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
>
> --
> C. Boyd
> 76 Crestmont by Midas
> East Tennessee
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] A/C compressor noit engaging [message #174225 is a reply to message #174210] |
Thu, 21 June 2012 18:46 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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[quote title=ljdavick wrote on Thu, 21 June 2012 12:23]Bill,
Is that 20-25 lbs with the jumper connected and the engine at 1,500 rpm?
It sure looks to me like changing that switch will dump your duracool.
Hopefully Roy will chime in.
Larry Davick
Fremont, California
The Mystery Machine
'76 (ish) Palm Beach
As everyone is suggesting you are likely out of refrigerant if you are a getting 25 lb reading with the engine off. That is a low pressure switch installed on the high pressure liquid line. Because of its location it is really a loss of charge switch. I believe it will require around 42 lbs of pressure to close the switch (engine off) Just add a little refrigerant with the engine off and an ohm meter on the contacts it should close just before you reach 50 lbs. I guess if you remove it you will release what is left in the system. Most vehicles these days the switch screws into a schrader valve and the charge isn't lost. You will probably be looking for a leak before recharging if this is the case.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] A/C compressor noit engaging [message #174269 is a reply to message #174214] |
Fri, 22 June 2012 06:19 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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We beat up airconditioners regularly in my work. I notice on the units we have - mostly Bard - almost all the fittings on the closed system have Schrader valves, and the switches either have a pin which opens the valve, or they are mounted on an adaptor which has the pin. Why not tee off the low side guage port with one of these, and fit a new switch to one side of the tee, using the other side for guages. Leave the old switch to fill the hole it's in. Check with your A/C parts house.
--johnny
'76 23' transmode bnorris
'76 palm beach
From: Emery Stora <emerystora@mac.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Thursday, June 21, 2012 3:52 PM
Subject: Re: [GMCnet] A/C compressor noit engaging
On Jun 21, 2012, at 1:46 PM, gene Fisher <mr.erfisher@gmail.com> wrote:
>
> then the pressure sw will work, (I have not seen a bad one yet)
>
> gene
>
Then I guess I never told you about the one I had to replace.
Like everything else, then can go bad.
Emery Stora
>
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] A/C compressor noit engaging [message #174290 is a reply to message #174227] |
Fri, 22 June 2012 10:38 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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| emerystora wrote on Thu, 21 June 2012 17:09 |
On Jun 21, 2012, at 5:46 PM, roy@gmcnet.org wrote:
>
>
> As everyone is suggesting you are likely out of refrigerant if you are a getting 25 lb reading with the engine off. That is a low pressure switch installed on the high pressure liquid line. Because of its location it is really a loss of charge switch. I believe it will require around 42 lbs of pressure to close the switch (engine off) Just add a little refrigerant with the engine off and an ohm meter on the contacts it should close just before you reach 50 lbs. I guess if you remove it you will release what is left in the system. Most vehicles these days the switch screws into a schrader valve and the charge isn't lost. You will probably be looking for a leak before recharging if this is the case.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
Roy
I think you should look again at the picture that Bill had referenced. That low pressure switch is actually on the low pressure side (the suction line).
Emery Stora
It is on the liquid line on all GMC's which is the high side. The fatter pipe above is the low side but i'm sure you already knew this .
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Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] A/C compressor noit engaging [message #174292 is a reply to message #174269] |
Fri, 22 June 2012 10:44 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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[quote title=Johnny Bridges wrote on Fri, 22 June 2012 04:19]We beat up airconditioners regularly in my work. I notice on the units we have - mostly Bard - almost all the fittings on the closed system have Schrader valves, and the switches either have a pin which opens the valve, or they are mounted on an adaptor which has the pin. Why not tee off the low side guage port with one of these, and fit a new switch to one side of the tee, using the other side for guages. Leave the old switch to fill the hole it's in. Check with your A/C parts house.
That would work fine but if you wanted to replace the original and function only as a loss of charge switch you would need to connect it to the high side liquid line.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] A/C compressor noit engaging [message #174300 is a reply to message #174297] |
Fri, 22 June 2012 11:44 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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[quote title=emerystora wrote on Fri, 22 June 2012 09:18]
On Jun 22, 2012, at 9:38 AM, roy@gmcnet.org wrote:
>>
>>
>> It is on the liquid line on all GMC's which is the high side. The fatter pipe above is the low side but i'm sure you already knew this .
>> _______________________________________________
Roy
Of course you are correct. I did know that. In fact, ere is something that I posted 7 years ago:
> On Jul 5, 2005, at 9:11 AM, Emery Stora wrote:
> That pressure switch is located in the high pressure line just behind the cover under the passenger side windshield.
>
> If you pull the plug off the switch you can jumper the two wires going into the plug to check the circuits. The pressure switch connects the two wires if there is sufficient pressure in the system.
>
> If you have the engine running with the air conditioner on and the plug removed from the switch, the clutch on the compressor will not engage. If you jump across the two wires in the plug you can see and hear the clutch engage. If the pressure switch is good and there is enough freon in the system then plugging in the connector to the pressure switch should do the same thing as shorting across the two wires in the plug.
However apparently I didn't have my head screwed on right yesterday. The excuse that I will use is that my GMC is 450 mies away from me right now so I couldn't go out and look.. A memory can play tricks on one.
My apologies for trying to correct you. I was wrong.
Emery Stora
_______________________________________________
No apologies necessary Emery we all see things differently at times and I know you knew it was on the liquid line as you have seen it on a lot of coaches. Is your coach still in the repair shop?
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Fri, 22 June 2012 11:47] Report message to a moderator |
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| Re: [GMCnet] A/C compressor noit engaging [message #174305 is a reply to message #174292] |
Fri, 22 June 2012 12:49 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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You have high side and low side fittings do you not? Simply use the high side one.
--johnny
From: "roy@gmcnet.org" <roy@gmcnet.org>
To: gmclist@temp.gmcnet.org
Sent: Friday, June 22, 2012 11:44 AM
Subject: Re: [GMCnet] A/C compressor noit engaging
[quote title=Johnny Bridges wrote on Fri, 22 June 2012 04:19]We beat up airconditioners regularly in my work. I notice on the units we have - mostly Bard - almost all the fittings on the closed system have Schrader valves, and the switches either have a pin which opens the valve, or they are mounted on an adaptor which has the pin. Why not tee off the low side guage port with one of these, and fit a new switch to one side of the tee, using the other side for guages. Leave the old switch to fill the hole it's in. Check with your A/C parts house.
That would work fine but if you wanted to replace the original and function only as a loss of charge switch you would need to connect it to the high side liquid line.
--
Roy Keen
Minden,NV
76 X Glenbrook
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] A/C compressor noit engaging [message #174316 is a reply to message #174309] |
Fri, 22 June 2012 14:26 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
Karma: 0
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Thanks for that update Emery, been wondering since Shawnee.
WOW according to Jim's Streets and Trips version of the Black List, your new town is right in the middle of a bunch of GMC'rs!
There was a young lady on the net trying to help another young lady from CO, maybe even from Longmont, to sell a barn stored GMC. Anyone know if that got done?
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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