| can I get a primer on AC service? [message #173569] |
Sat, 16 June 2012 19:25  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Senior Member |
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I know the the theory of refrigeration but not the execution.
I find myself with three vehicles that need service. I have a case of duracool and a cheap 1.5 CFM vac pump.
Now what?
- last winter the ac compressor on the Expedition went out (at the bearing, no contamination) We installed a new compressor and left it until now.
- last week i had a small bump with hte Civic and cracked a line.
- If i'm successful with these two, i'll take on the coach.
Questions:
- did all the oil leak out with the R134 in the Civic? It was a small crack half way up the condensor?
- Absent a vac gauge, how long should the pump run to evacuate the system?
thanks
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: [GMCnet] can I get a primer on AC service? [message #173572 is a reply to message #173569] |
Sat, 16 June 2012 19:40  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Regards,
Rob M.
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dave silva
Sent: Sunday, 17 June 2012 10:26 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] can I get a primer on AC service?
I know the the theory of refrigeration but not the execution.
I find myself with three vehicles that need service. I have a case of
duracool and a cheap 1.5 CFM vac pump.
Now what?
- last winter the ac compressor on the Expedition went out (at the bearing,
no contamination) We installed a new compressor and left it until now.
- last week i had a small bump with hte Civic and cracked a line.
- If i'm successful with these two, i'll take on the coach.
Questions:
- did all the oil leak out with the R134 in the Civic? It was a small crack
half way up the condensor?
- Absent a vac gauge, how long should the pump run to evacuate the system?
thanks
--
Dave & Ellen Silva
1972 Revcon Olds 455, toro drive train. All Stock
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GMCnet mailing list
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] can I get a primer on AC service? [message #173574 is a reply to message #173572] |
Sat, 16 June 2012 19:48 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dave,
It appears my PC has joined the JimK club of invisible replies.
I'm not knowledgeable enough on the A/C system to comment.
Regards,
Rob M.
-----Original Message-----
From: Robert Mueller
Regards,
Rob M.
-----Original Message-----
From: dave silva
I know the the theory of refrigeration but not the execution.
I find myself with three vehicles that need service. I have a case of
duracool and a cheap 1.5 CFM vac pump.
Now what?
- last winter the ac compressor on the Expedition went out (at the bearing,
no contamination) We installed a new compressor and left it until now.
- last week i had a small bump with hte Civic and cracked a line.
- If i'm successful with these two, i'll take on the coach.
Questions:
- did all the oil leak out with the R134 in the Civic? It was a small crack
half way up the condensor?
- Absent a vac gauge, how long should the pump run to evacuate the system?
thanks
--
Dave
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] can I get a primer on AC service? [message #173590 is a reply to message #173574] |
Sat, 16 June 2012 21:04 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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You really need at least a gauge on the low pressure side.
The process is to vacuum the system and watch the gauge. You are no only trying to remove any moisture in the system but you are verifying that the system does not have any leaks when you vacuum (evacuate) it.
Attach the vacuum pump and watch the gauge. Depending on your height above sea level and a few other things, you should see about 28 or 29 inches. When you turn off the pump and close the valve to the system the vacuum should remain constant for a 1/2 hour or so. Some people believe that 2 to 8 hours is required.
After vacuuming and with the system still sealed you need to add the freon. Depending on the type of freon R-12, r-134, Duracool, etc. you are looking to add enough freon to meet certain pressures on the low side. Emery has come up with an ideal pressure for Duracool of 20 PSI with the AC on full and the engine running about 1500 RPM.
Without at least a gauge for both vacuum and pressure on the low side I do not know how you will evacuate and charge your system.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] can I get a primer on AC service? [message #173622 is a reply to message #173590] |
Sun, 17 June 2012 06:05 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Senior Member |
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Thanks - mission accomplished.
I do have the gauge that comes with the R134 refill can. Earlier in the week, i repaired the leak and shot a bit of Duracool n the the system to pressurize it.
The pressure had not fallen over several days. This morning I ran the vacuum pump for a while, and added Duracool until until it stared blowing cold. I think i have 25 PSI.
It's blowing cold.
I'll experiment with bleeding some off later today when the weather gets hotter.
My other question is about oil;
I know when the compressor on the Expedidition was removed it gushed a big mess of oily R134
But the Honda had a small leak up high on one of the lines. Would the oil have remained in the system?
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: can I get a primer on AC service? [message #173637 is a reply to message #173569] |
Sun, 17 June 2012 10:07 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Sounds like you need to buy 2 gauge sets----134a and R12 due to the year ranges of the vehicles. If you don't see oil smear at the leak you probably had a slow decompression and most stayed behind. GMC---Also on the GMC R12 system if you are using R12, there is the Old School site glass on the dryer. After evacuation of system with the pump, close all the valves, wait to see if vac holds, swap the pump for the R12 canister, open the R12 canister valve, burp the line at the junction of the gauge head and the yellow line from the tank, run the engine on high idle and high fan, open the LOW side gauge only, till stabilizes, turn on compressor,(you may need to jump the low pressure switch to get cluch engagement can't remember if this vintage has that), add R12 by weight to match sticker OR watch until site glass goes clear (liquid 100%) and watch the LOW/HI pressures. These will vary with RPM/TEMP/HUMIDITY and fan clutch status. Depending on a warm day you may see roughly 35-40 low side and 225 high side when the glass goes clear. The textbook only exact way to get what they want in there is precision scale after evac. The armchair way is site glass and gauges. If it's 110 out you could hit 300 on the high side but you don't want the system running that way if its 80 out as then it will be over 300 on a hot soak situation. CAUTION--Don't open the red HI side valve! The HI gauge reads with the valve CLOSED!
After charging close the LO valve on gauge and the tank and disconnect (quickly the low side at the vehicle). Connect blue hose back to keeper on set. Turn off AC and then turn of vehicle. Wait for freon HI side to equalize and then quickly disconnect HI side and return red line to keeper. I sniff the Schraders with leak tool to see they are sealed and then cap. Take off the saftey glasses you have been wearing this whole time.
For HC12 (and a whole lot of ther things) Emery is the man.
For 134a, these cars are "newer" (haha) and so I only have the cheapo low side can gauge for topping off---have not had to evac and do full service. Sound like for the Honda you need 134a gauges so you can evac.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] can I get a primer on AC service? [message #173651 is a reply to message #173622] |
Sun, 17 June 2012 12:04 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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It sounds like the Honda should be OK with the existing oil. On the other one you need to estimate the amount of oil lost and replace it. Usually when replacing an AC component you can look up in the maintenance manual how much to add for each replaced component. Also when adding oil be sure to use exactly the same oil as it had before. NAPA and I believe AZ can look up your vehicle and tell you what oil (and weight) to use.
Do not get carried away and add too much oil. Doing so can lock up a compressor.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] can I get a primer on AC service? [message #173653 is a reply to message #173622] |
Sun, 17 June 2012 12:17 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[quote title=hertfordnc wrote on Sun, 17 June 2012 04:05]Thanks - mission accomplished.
I do have the gauge that comes with the R134 refill can. Earlier in the week, i repaired the leak and shot a bit of Duracool n the the system to pressurize it.
The pressure had not fallen over several days. This morning I ran the vacuum pump for a while, and added Duracool until until it stared blowing cold. I think i have 25 PSI.
It's blowing cold.
I'll experiment with bleeding some off later today when the weather gets hotter.
My other question is about oil;
I know when the compressor on the Expedidition was removed it gushed a big mess of oily R134
But the Honda had a small leak up high on one of the lines. Would the oil have remained in the system?
I wouldn't be too quick to bleed the low side to 20 lbs some vehicles need to be at 25-30 lbs depending on the ambient air temperature. Also you will not likely be able to determine a full charge with the sight glass that was for use with R12.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] can I get a primer on AC service? [message #173705 is a reply to message #173653] |
Mon, 18 June 2012 00:39 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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[quote title=roy1 wrote on Sun, 17 June 2012 12:17]| hertfordnc wrote on Sun, 17 June 2012 04:05 |
Thanks - mission accomplished.
I do have the gauge that comes with the R134 refill can. Earlier in the week, i repaired the leak and shot a bit of Duracool n the the system to pressurize it.
The pressure had not fallen over several days. This morning I ran the vacuum pump for a while, and added Duracool until until it stared blowing cold. I think i have 25 PSI.
It's blowing cold.
I'll experiment with bleeding some off later today when the weather gets hotter.
My other question is about oil;
I know when the compressor on the Expedidition was removed it gushed a big mess of oily R134
But the Honda had a small leak up high on one of the lines. Would the oil have remained in the system?
I wouldn't be too quick to bleed the low side to 20 lbs some vehicles need to be at 25-30 lbs depending on the ambient air temperature. Also you will not likely be able to determine a full charge with the sight glass that was for use with R12.
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I agree. If it is cooling to your satisfaction, leave it that way.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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