| Problem Charging AC w/Duracool [message #279054] |
Thu, 04 June 2015 12:57  |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Summer heat is here so I could no longer procrastinate getting my Dash AC working. I have an after-market under-dash unit that uses the original compressor and condenser. The original evaporator is bypassed. The system worked really well but the AC has not been used for about two years and was empty of R12. I got the hose and Duracool and set out to charge the system. Things were going well and got nice cool air coming out the vents with the first can. Ended putting in about 2 1/2 cans of Duracool. Readings Low side pressure was about 25 with compressor on @ 1,500 rmp but became somewhat erratic. The Duracool kit came with an oil tester and the oil checked out fine.
Shut down engine and within a couple of minutes smelled something and noticed smoke from front of compressor. Put a fan blowing on it and reattached the gauge and found a static pressure of about 120 on the the low side with the engine off. (outside temp here about 85). Do I have too much refrigerant or a compressor or clutch problem or ?
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Problem Charging AC w/Duracool [message #279055 is a reply to message #279054] |
Thu, 04 June 2015 13:14  |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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After thought, compressor had not run for over two years or so and had the intake manifold replaced during that time so maybe some oil on compressor and I am paranoid!
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Problem Charging AC w/Duracool [message #279071 is a reply to message #279055] |
Thu, 04 June 2015 18:08 |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Senior Member |
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George B. wrote on Thu, 04 June 2015 11:14After thought, compressor had not run for over two years or so and had the intake manifold replaced during that time so maybe some oil on compressor and I am paranoid!
When things cooled down, I was able to take a look. Noticed some very small metal filings on the hoses that run next to the AC pulley. Could this be from the pulley clutch engaging for the first time in a couple of years or signs of a bad AC clutch bearing?
How hard to replace the clutch & pulley on the front of the AC compressor?
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Problem Charging AC w/Duracool [message #279073 is a reply to message #279054] |
Thu, 04 June 2015 18:13 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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I had a problem with the belt slipping causing the AC clutch to heat up and smoke.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Problem Charging AC w/Duracool [message #279080 is a reply to message #279071] |
Thu, 04 June 2015 19:13 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Sir, maybe look at ac hoses right above pulley. They might be rubbing..
George B. wrote on Thu, 04 June 2015 19:08George B. wrote on Thu, 04 June 2015 11:14After thought, compressor had not run for over two years or so and had the intake manifold replaced during that time so maybe some oil on compressor and I am paranoid!
When things cooled down, I was able to take a look. Noticed some very small metal filings on the hoses that run next to the AC pulley. Could this be from the pulley clutch engaging for the first time in a couple of years or signs of a bad AC clutch bearing?
How hard to replace the clutch & pulley on the front of the AC compressor?
C. Boyd
76 Crestmont
East Tennessee
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| Re: Problem Charging AC w/Duracool [message #279094 is a reply to message #279071] |
Thu, 04 June 2015 23:21 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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If there was no residual pressure left in the system it's possible you have air in it and that may be freezing, causing a blockage that would drive the pressure up and cause the clutch to slip. If the front seal is leaking oil (and refrigerant), that will also cause the clutch to slip. If the clutch surfaces were rusty, that could also cause slippage. In either case, the metal filings are probably from the clutch slipping, and that would result in heat and some foul smelling smoke. If it was just hot with no filings, that could be the belt slipping, also causing heat and possible smoke.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Problem Charging AC w/Duracool [message #279159 is a reply to message #279094] |
Fri, 05 June 2015 17:49 |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Bullitthead wrote on Thu, 04 June 2015 21:21If there was no residual pressure left in the system it's possible you have air in it and that may be freezing, causing a blockage that would drive the pressure up and cause the clutch to slip. If the front seal is leaking oil (and refrigerant), that will also cause the clutch to slip. If the clutch surfaces were rusty, that could also cause slippage. In either case, the metal filings are probably from the clutch slipping, and that would result in heat and some foul smelling smoke. If it was just hot with no filings, that could be the belt slipping, also causing heat and possible smoke.
I checked the system again today. I left the gauge overnight and the low side static pressure was 100 this morning. Started the engine & turned on the AC and the pressure went down to 25 and the evaporator was blowing about 30-35 degrees @1000 rpm. The compressor did not cycle while I had it on. It did make some noise when engaged, a slight tapping/clicking sound. Is this the normal sound of one of these compressors when engaged.?
I did not detect any smoke or burning smell as I did yesterday. Hopefully was just burning off some residue accumulated over two years of non use. However the fine metal filings do bother me, perhaps the clutch breaking in again or as mentioned slipping. At this point not really confident to button things up and let it run.
Driving from Las Vegas to Los Angeles next week and really would like some AC. However I do have one of the best GMC after market accessories: The Wind Wings, ya gotta have em.
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: [GMCnet] Problem Charging AC w/Duracool [message #279164 is a reply to message #279159] |
Fri, 05 June 2015 18:28 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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The static pressure doesn't rally have any meaning except to tell you that you have some charge.
You should check the low side pressure at 1500 rpm.
If it drops much lower than 25 it would indicate an undercharge. It would run very cold but you migh freeze up your evaporator and block airflow through your ducts.
Report back with that pressure.
Emery Stora
77 Kingsley
Frederick, CO
> On Jun 5, 2015, at 4:49 PM, GEORGE BUTTS wrote:
>
> Bullitthead wrote on Thu, 04 June 2015 21:21
>> If there was no residual pressure left in the system it's possible you have air in it and that may be freezing, causing a blockage that would
>> drive the pressure up and cause the clutch to slip. If the front seal is leaking oil (and refrigerant), that will also cause the clutch to slip. If
>> the clutch surfaces were rusty, that could also cause slippage. In either case, the metal filings are probably from the clutch slipping, and that
>> would result in heat and some foul smelling smoke. If it was just hot with no filings, that could be the belt slipping, also causing heat and
>> possible smoke.
>
>
> I checked the system again today. I left the gauge overnight and the low side static pressure was 100 this morning. Started the engine & turned on
> the AC and the pressure went down to 25 and the evaporator was blowing about 30-35 degrees @1000 rpm. The compressor did not cycle while I had it on.
> It did make some noise when engaged, a slight tapping/clicking sound. Is this the normal sound of one of these compressors when engaged.?
>
> I did not detect any smoke or burning smell as I did yesterday. Hopefully was just burning off some residue accumulated over two years of non use.
> However the fine metal filings do bother me, perhaps the clutch breaking in again or as mentioned slipping. At this point not really confident to
> button things up and let it run.
>
> Driving from Las Vegas to Los Angeles next week and really would like some AC. However I do have one of the best GMC after market accessories: The
> Wind Wings, ya gotta have em.
> --
> George Butts
> Las Vegas Nevada
> 73 "Custom 26' Q" & 76 23' Birchaven
> 71 Honda 600 Coupe & 01 Tracker Toads
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| Re: Problem Charging AC w/Duracool [message #279168 is a reply to message #279054] |
Fri, 05 June 2015 19:44 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Also I like Terry's theory of moisture in the lines. This can freeze at the expansion valve. But you did not give us pressures during the fail mode. I suspect high side was very high causing clutch slippage. Those clutches will shed metal if they are forced to slip. It 's a bit of a "fuse" by design. Pump down the system for 1hour and recharge. Bad practice to not pull a vacuum on empty system.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Problem Charging AC w/Duracool [message #279178 is a reply to message #279168] |
Fri, 05 June 2015 22:57 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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JohnL455 wrote on Fri, 05 June 2015 18:44Also I like Terry's theory of moisture in the lines. This can freeze at the expansion valve. But you did not give us pressures during the fail mode. I suspect high side was very high causing clutch slippage. Those clutches will shed metal if they are forced to slip. It 's a bit of a "fuse" by design. Pump down the system for 1hour and recharge. Bad practice to not pull a vacuum on empty system.
There is a blow-off valve on the back of the compressor if the high side gets too high. Also in low humidity areas you can bypass the condenser mounted thermostat since the chances of icing are minimal.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Problem Charging AC w/Duracool [message #279184 is a reply to message #279159] |
Sat, 06 June 2015 01:36 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Compressors do make some clicking noises, they make more when they get well used. The clutches should only make one click when engaging and should not be making any noise while running. There should not be any "clacking" noise when the system is on. If there is no evidence of oil leakage at the front seal or anywhere else in the system, you can install about 2 ounces of oil without risk of having too much oil in the system. That may make it a little quieter. Use mineral oil with R 12 or Duracool.
The clutches are metal to metal contact, and after some time of non use those mating surfaces are going to rust just like a disc brake that has been sitting for a few weeks or more out in the humidity. Rust is not going to make the absolute connection and so it will have to be worn away by repeated engagement of the clutch. Use some compressed air to blow it out while the engine is running and the A/C is OFF, then turn it on a couple of times and then repeat with the air blast, that should get the clutch cleaned out well enough.
As John said, always draw a vacuum on a system that is being recharged after a long period of non use, or has unknown quantities of unknown substances inside. Use a heat gun or hair dryer on the accumulator and drier when vacuuming to make sure they are completely evacuated. And as Emery said, the residual pressure only indicate that there is a minimum amount of some kind of outgassing chemical in the system. It could be 4 ounces or 2 lbs. and the residual pressure will be the same, depending on the size of the system. Drawing the system down to maximum possible vacuum will boil off any moisture present, remove any remaining refrigerants, allow much easier lubricant installation, let you know if the system leaks excessively, and assure you of the proper charge amount (if you are using the same as what the manufacturer designed the system to use).
When charging with alternative chemicals, only install enough to get leftover cold coming back to the compressor, but never enough to cause frost on the return line, as that could allow liquid (unevaporated) refrigerant to enter the compressor, and the liquid cannot be compressed. That will cause excessive noise (clacking) and clutch and belt slippage and likely compressor failure. The return line should sweat, but no frost.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Problem Charging AC w/Duracool [message #279186 is a reply to message #279054] |
Sat, 06 June 2015 02:55 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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On Dan Gregg's coach we had a similar problem. I forget which rally we were at but it was a spring one down south. Dan had not used the AC all winter before. The clutch would make noise when engaged and no noise when it wasn't. We found that the clutch was just slightly hitting a body brace which only scraped / hit when the clutch was engaged. Dan had replaced the belt the previous fall and not used the AC since then. The problem turned out to be the 3/8" bellt he installed, rather than 7/16" belt he should have used. The slight difference allowed the compressor to sit slightly farther away from the engine and hit or scrape the body brace. We took a quick trip in his VW to a local AutoZone store and bought the correct length 7/16" width belt. Installing that solved his problem.
Check that you have the correct belt both width and length. If in doubt, use the shortest belt possible.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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