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| [GMCnet] A/C Problem [message #359234] |
Wed, 07 October 2020 16:40  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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A couple of days ago, I got the GMC out and washed it, top to bottom. I'm
not sure the roof had been washed all over since the 2002 paint job!
Needless to say, it was DIRTY! Dawn mixed with lots of water and 83 yo
elbow grease finally got it looking pretty good.
Then yesterday I got inside, only to find lots of mildew. Seems sitting
closed up since 26 November 2019 wasn't its favorite condition. I got most
of that, including every square inch inside and outside of the
refrigerator, cured with Lysol wipes and more elbow grease.
Today I tried the TroyBilt generator. 10-15 seconds of cranking had it
running like a top and it was happy to power the roof air conditioner.
Then I went to fill the gas tanks (24 gallons) -- nope, I didn't top them
off before parking it. That's when I found out that the dash air no longer
produces even cool air. When I parked it last November, it was cooling
well. Perhaps needed a little more Freeze 12 but not bad at all for having
been untouched for 5 years+. But today, NO cooling. So, the refrigerant
must have leaked out, right? I've got a pretty good manifold set, and I've
used it a number of times over the past 15-20 years. And I've rebuilt,
redesigned, and repaired several auto A/C's -- but I'm NO EXPERT! I've
been lucky -- all the bits and pieces I've used have all worked, except for
the odd seal, hose, or belt which anyone could find and replace.
When I connected the manifold set, the high and low gauges, as expected,
read the same. I was a bit surprised to see 95 psi static, but so be it.
Then I started the engine with the A/C turned on. Still reading the same
on both gauges! Still about 95 psi! Hmmmm... I finally realized (with
being able to see it) that the compressor clutch was not engaging. Jumping
power to it directly from the chassis battery, I could hear the clutch
engage and the engine pick up a little load. But I saw essentially no
change on either pressure gauge!
Finally, I connected a fresh can of Freeze 12 to the filler hose. Opening
that caused the low pressure to rise sharply -- with no effect on the high
pressure side. Later, I disconnected the Freeze 12 and bled off most of
the pressure on the low side -- still no effect on the high side. Opening
the high side slightly caused a slow drop in that pressure -- I didn't
drain off much. It sits now with maybe 20 psi on the low side and 85 psi
on the high side -- after an hour or more unattended. The inside of the
coach is nice and cool -- with the roof air running on shore power!
SO, what say ye? What's plugged? I've never heard anything abnormal
sounding from the Sanden-clone compressor I've been using for about 10
years, so I find it hard to believe it's failed internally. But if not,
why is there no change in any pressure when I can tell it's running?
Where's the energy that the engine's obviously putting into it going?
Nope, the gauges are not stuck -- they respond perfectly normally.
After determining it was 111*F outside, I quit (only to have the
thermometer say it's only 91*F). I've no idea whether to attack the
thermo-expansion valve or the compressor or ???. Sure hope one of you
more-experienced A/C experts has an idea.
Thanks!
Ken H.cwipersetc.com
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] A/C Problem [message #359239 is a reply to message #359234] |
Wed, 07 October 2020 17:36  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I would suspect the dessicant/drier/filter. Automotive A/C systems do not
like to sit without being exercised. Seals become elliptical from the
shafts sitting in one place for long periods of time, even though they are
supposed to be a completely sealed system, they are victims of
condensation, like the inside of your coach and refrigerator was. Just what
I would check first.
Jim Hupy
Salem, Oregon
On Wed, Oct 7, 2020 at 2:41 PM Ken Henderson via Gmclist <
gmclist@list.gmcnet.org> wrote:
> A couple of days ago, I got the GMC out and washed it, top to bottom. I'm
> not sure the roof had been washed all over since the 2002 paint job!
> Needless to say, it was DIRTY! Dawn mixed with lots of water and 83 yo
> elbow grease finally got it looking pretty good.
>
> Then yesterday I got inside, only to find lots of mildew. Seems sitting
> closed up since 26 November 2019 wasn't its favorite condition. I got most
> of that, including every square inch inside and outside of the
> refrigerator, cured with Lysol wipes and more elbow grease.
>
> Today I tried the TroyBilt generator. 10-15 seconds of cranking had it
> running like a top and it was happy to power the roof air conditioner.
> Then I went to fill the gas tanks (24 gallons) -- nope, I didn't top them
> off before parking it. That's when I found out that the dash air no longer
> produces even cool air. When I parked it last November, it was cooling
> well. Perhaps needed a little more Freeze 12 but not bad at all for having
> been untouched for 5 years+. But today, NO cooling. So, the refrigerant
> must have leaked out, right? I've got a pretty good manifold set, and I've
> used it a number of times over the past 15-20 years. And I've rebuilt,
> redesigned, and repaired several auto A/C's -- but I'm NO EXPERT! I've
> been lucky -- all the bits and pieces I've used have all worked, except for
> the odd seal, hose, or belt which anyone could find and replace.
>
> When I connected the manifold set, the high and low gauges, as expected,
> read the same. I was a bit surprised to see 95 psi static, but so be it.
> Then I started the engine with the A/C turned on. Still reading the same
> on both gauges! Still about 95 psi! Hmmmm... I finally realized (with
> being able to see it) that the compressor clutch was not engaging. Jumping
> power to it directly from the chassis battery, I could hear the clutch
> engage and the engine pick up a little load. But I saw essentially no
> change on either pressure gauge!
>
> Finally, I connected a fresh can of Freeze 12 to the filler hose. Opening
> that caused the low pressure to rise sharply -- with no effect on the high
> pressure side. Later, I disconnected the Freeze 12 and bled off most of
> the pressure on the low side -- still no effect on the high side. Opening
> the high side slightly caused a slow drop in that pressure -- I didn't
> drain off much. It sits now with maybe 20 psi on the low side and 85 psi
> on the high side -- after an hour or more unattended. The inside of the
> coach is nice and cool -- with the roof air running on shore power!
>
> SO, what say ye? What's plugged? I've never heard anything abnormal
> sounding from the Sanden-clone compressor I've been using for about 10
> years, so I find it hard to believe it's failed internally. But if not,
> why is there no change in any pressure when I can tell it's running?
> Where's the energy that the engine's obviously putting into it going?
> Nope, the gauges are not stuck -- they respond perfectly normally.
>
> After determining it was 111*F outside, I quit (only to have the
> thermometer say it's only 91*F). I've no idea whether to attack the
> thermo-expansion valve or the compressor or ???. Sure hope one of you
> more-experienced A/C experts has an idea.
>
> Thanks!
>
> Ken H.cwipersetc.com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] A/C Problem [message #359240 is a reply to message #359234] |
Wed, 07 October 2020 18:12 |
Marsh Wilkes
Messages: 155
Registered: January 2004
Karma: -3
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Senior Member |
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Hi Ken,
I'm no automotive air expert, but I've done extensive maintenance and even
design
improvements on 35 ton multi-zone R-22 units that I later converted to 407C.
I actually have to go to work right now, I will ponder on your problem while
at work
and get back with you later. Someone will probably pipe up in the mean time.
From what I
am hearing though, it sounds like the metering valve (expansion valve) is
totally blocked some how.
Marsh Wilkes
Perry fl
-----Original Message-----
From: Ken Henderson via Gmclist
Sent: Wednesday, October 07, 2020 5:40 PM
To: GMC Mail List
Cc: Ken Henderson
Subject: [GMCnet] A/C Problem
A couple of days ago, I got the GMC out and washed it, top to bottom. I'm
not sure the roof had been washed all over since the 2002 paint job!
Needless to say, it was DIRTY! Dawn mixed with lots of water and 83 yo
elbow grease finally got it looking pretty good.
Then yesterday I got inside, only to find lots of mildew. Seems sitting
closed up since 26 November 2019 wasn't its favorite condition. I got most
of that, including every square inch inside and outside of the
refrigerator, cured with Lysol wipes and more elbow grease.
Today I tried the TroyBilt generator. 10-15 seconds of cranking had it
running like a top and it was happy to power the roof air conditioner.
Then I went to fill the gas tanks (24 gallons) -- nope, I didn't top them
off before parking it. That's when I found out that the dash air no longer
produces even cool air. When I parked it last November, it was cooling
well. Perhaps needed a little more Freeze 12 but not bad at all for having
been untouched for 5 years+. But today, NO cooling. So, the refrigerant
must have leaked out, right? I've got a pretty good manifold set, and I've
used it a number of times over the past 15-20 years. And I've rebuilt,
redesigned, and repaired several auto A/C's -- but I'm NO EXPERT! I've
been lucky -- all the bits and pieces I've used have all worked, except for
the odd seal, hose, or belt which anyone could find and replace.
When I connected the manifold set, the high and low gauges, as expected,
read the same. I was a bit surprised to see 95 psi static, but so be it.
Then I started the engine with the A/C turned on. Still reading the same
on both gauges! Still about 95 psi! Hmmmm... I finally realized (with
being able to see it) that the compressor clutch was not engaging. Jumping
power to it directly from the chassis battery, I could hear the clutch
engage and the engine pick up a little load. But I saw essentially no
change on either pressure gauge!
Finally, I connected a fresh can of Freeze 12 to the filler hose. Opening
that caused the low pressure to rise sharply -- with no effect on the high
pressure side. Later, I disconnected the Freeze 12 and bled off most of
the pressure on the low side -- still no effect on the high side. Opening
the high side slightly caused a slow drop in that pressure -- I didn't
drain off much. It sits now with maybe 20 psi on the low side and 85 psi
on the high side -- after an hour or more unattended. The inside of the
coach is nice and cool -- with the roof air running on shore power!
SO, what say ye? What's plugged? I've never heard anything abnormal
sounding from the Sanden-clone compressor I've been using for about 10
years, so I find it hard to believe it's failed internally. But if not,
why is there no change in any pressure when I can tell it's running?
Where's the energy that the engine's obviously putting into it going?
Nope, the gauges are not stuck -- they respond perfectly normally.
After determining it was 111*F outside, I quit (only to have the
thermometer say it's only 91*F). I've no idea whether to attack the
thermo-expansion valve or the compressor or ???. Sure hope one of you
more-experienced A/C experts has an idea.
Thanks!
Ken H.cwipersetc.com
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Unsubscribe or Change List Options:
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| Re: [GMCnet] A/C Problem [message #359254 is a reply to message #359234] |
Wed, 07 October 2020 22:40 |
Marsh Wilkes
Messages: 155
Registered: January 2004
Karma: -3
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Senior Member |
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Hi Ken,
Thought about it a little.
Got some guesses and some questions, mostly just conjecture.
Why was the clutch not engaging, it should cycle off only on low pressure,
an unrelated problem? In theory the bulb in the thermostatic diaphragm
could have lost it's charge closing the expansion valve. That rarely happens
as it is a hermetic device and I am not sure it could close totally. From
what
you describe, it seems something in the system is totally blocked, but if
that's
the case and the compressor is pumping, you would expect to see a drop in
the
low side pressure, but may be not much rise in the high side as there is
little refrigerant
to pump, since it cant return to the low side. Possibly the compressor is
damaged and ran
long enough to plug the orifice, with debris and is not pumping much anyway.
Just a bunch
of guesses. What's needed is some more testing, starting with rerunning what
has already been done.
As Jim said a blocked filter/dryer is a possibility, I wouldn't expect a
complete blockage, but I don't
know for sure. The 95 PSI would seem to indicate liquid in the system (all
the refrigerant has not leaked
out) based on the ambient temperature and best I could find of a
temp/pressure chart for Freeze 12, actually
a very close correlation. Unless you are just getting some really spurious
indications (check everything again) it would
seem that you are going to have to open the system any way. If you have a
way to recover the refrigerant it would
be interesting to know how much refrigerant was remaining, although that
probably would not mean much in terms
of diagnosing the problem. Surely someone else will speak up with some good
ideas on trouble shooting. Do you have
a good local AC guy, I know you have a good machinist, a good auto electric
guy and I think a good welder among other
trusted experts.
Marsh Wilkes
Perry Fl
-----Original Message-----
From: Ken Henderson via Gmclist
Sent: Wednesday, October 07, 2020 5:40 PM
To: GMC Mail List
Cc: Ken Henderson
Subject: [GMCnet] A/C Problem
A couple of days ago, I got the GMC out and washed it, top to bottom. I'm
not sure the roof had been washed all over since the 2002 paint job!
Needless to say, it was DIRTY! Dawn mixed with lots of water and 83 yo
elbow grease finally got it looking pretty good.
Then yesterday I got inside, only to find lots of mildew. Seems sitting
closed up since 26 November 2019 wasn't its favorite condition. I got most
of that, including every square inch inside and outside of the
refrigerator, cured with Lysol wipes and more elbow grease.
Today I tried the TroyBilt generator. 10-15 seconds of cranking had it
running like a top and it was happy to power the roof air conditioner.
Then I went to fill the gas tanks (24 gallons) -- nope, I didn't top them
off before parking it. That's when I found out that the dash air no longer
produces even cool air. When I parked it last November, it was cooling
well. Perhaps needed a little more Freeze 12 but not bad at all for having
been untouched for 5 years+. But today, NO cooling. So, the refrigerant
must have leaked out, right? I've got a pretty good manifold set, and I've
used it a number of times over the past 15-20 years. And I've rebuilt,
redesigned, and repaired several auto A/C's -- but I'm NO EXPERT! I've
been lucky -- all the bits and pieces I've used have all worked, except for
the odd seal, hose, or belt which anyone could find and replace.
When I connected the manifold set, the high and low gauges, as expected,
read the same. I was a bit surprised to see 95 psi static, but so be it.
Then I started the engine with the A/C turned on. Still reading the same
on both gauges! Still about 95 psi! Hmmmm... I finally realized (with
being able to see it) that the compressor clutch was not engaging. Jumping
power to it directly from the chassis battery, I could hear the clutch
engage and the engine pick up a little load. But I saw essentially no
change on either pressure gauge!
Finally, I connected a fresh can of Freeze 12 to the filler hose. Opening
that caused the low pressure to rise sharply -- with no effect on the high
pressure side. Later, I disconnected the Freeze 12 and bled off most of
the pressure on the low side -- still no effect on the high side. Opening
the high side slightly caused a slow drop in that pressure -- I didn't
drain off much. It sits now with maybe 20 psi on the low side and 85 psi
on the high side -- after an hour or more unattended. The inside of the
coach is nice and cool -- with the roof air running on shore power!
SO, what say ye? What's plugged? I've never heard anything abnormal
sounding from the Sanden-clone compressor I've been using for about 10
years, so I find it hard to believe it's failed internally. But if not,
why is there no change in any pressure when I can tell it's running?
Where's the energy that the engine's obviously putting into it going?
Nope, the gauges are not stuck -- they respond perfectly normally.
After determining it was 111*F outside, I quit (only to have the
thermometer say it's only 91*F). I've no idea whether to attack the
thermo-expansion valve or the compressor or ???. Sure hope one of you
more-experienced A/C experts has an idea.
Thanks!
Ken H.cwipersetc.com
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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] A/C Problem [message #359257 is a reply to message #359234] |
Thu, 08 October 2020 00:51 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Ken 83 is only a number as long as you can keep going your not old. I know a 96 year old that is still driving a 40 ft Monico pusher with a pick up in tow. When my wife tells me I’m too old to drive a Motorhome I remind her about nick . that high pressure you found before trying to start your a/c is normal at high ambient temperature even with the system low on refrigerant. Keep those wheels rollin it’ll keep you young for a lot longer. I’m an octogenarian also nothing like greasy hands and and jeans to put a smile on my face.
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Thu, 08 October 2020 00:55] Report message to a moderator |
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| Re: [GMCnet] A/C Problem [message #359264 is a reply to message #359257] |
Thu, 08 October 2020 09:10 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Ken,
What you are seeing (and I believe you) makes no sense unless you have at least two simultaneous problems.
Here are my votes, but I don't have any cures in mind.
The compressor has to have most of the discharge valves not functioning. If it pumped at all, the suction side would have pulled down.
There must be a liquid line blockage. This could easily happen in the TEX valve. If there were not, the low side would be coming up as expected.
My memory about this is shaky, but early in the No-R12 days, I had an A/C dummy load we used in dyno that got plugged up with stuff that seemed to be like putty. We had no idea what this stuff was or where it had come from. I worked all my contacts and one of them had seen a similar issue when the mineral oil of a R-12 system had mixed with the wrong PAL or ester oil in the 134 system.... And the recording ends there.
So, if you have the same goo, I can easily believe that it both made the pumps valves hang open and plugged up the TEX. Unfortunately and as written, I do not know what to do about it. In my case, the pump still worked and I had one of my techs disassemble and clean the regulating valves in the dummy load.
Please let us all know when you get it figured out.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] A/C Problem [message #359272 is a reply to message #359234] |
Thu, 08 October 2020 12:15 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Guessing stuck valves too. Did you evacuate the system before charging last year? Moisture may have made bad sludge. I’m no Sanden expert but betting that they don’t go 50 years like an A6
John Lebetski
Woodstock, IL
77 Eleganza II
[Updated on: Thu, 08 October 2020 12:15] Report message to a moderator |
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