| AC won't take a charge?? [message #86881] |
Tue, 01 June 2010 21:32  |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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I'm trying to charge my dash air system with Duracool.
I'm using the r134 can adapter with the built in pressure gauge.
I put in 1/2 a can and the pressure is way up there like 70 lbs.
When I engage the AC clutch it really sounds like its loading up like there is a blockage somewhere.
The system was empty, and was actually under vacuum as it was just at the AC shop. They ran hoses to my second evap under the couch. They also replaced the dryer and fixed a leak in the condenser. But the original hoses were OK they said.
So I have lot of volume to fill, 1 can should just disappear shouldn't it?
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: AC won't take a charge?? [message #86882 is a reply to message #86881] |
Tue, 01 June 2010 22:04  |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
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| Quote: |
I put in 1/2 a can and the pressure is way up there like 70 lbs.
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Are you charging on the LOW side? If you are charging on the low side see if you have pressure in the system by depressing the high side schrader valve to see if it has pressure. If it doesn't then the refrigerant is not getting into the system. Perhaps the valve in the suction side is not being depressed by the hose set. If it does have a charge is the 70# with the compressor running?
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: AC won't take a charge?? [message #86886 is a reply to message #86882] |
Tue, 01 June 2010 22:28 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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Well I'm on the small fitting. on the big hose.
And yes if I press the schrader on the high side I get pressure.
I suppose I'll have to open it up and see if something is plugged.
Grrrr
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: AC won't take a charge?? [message #86889 is a reply to message #86886] |
Tue, 01 June 2010 22:37 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
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| Keith V wrote on Tue, 01 June 2010 20:28 |
Well I'm on the small fitting. on the big hose.
And yes if I press the schrader on the high side I get pressure.
I suppose I'll have to open it up and see if something is plugged.
Grrrr
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As I recall, you charge R12A with the can inverted which is the reverse of how you do it with 12 or 134. Also, are you running the compressor when you are doing this? You should be, otherwise all you will do is put a static pressure on the system. The compressor needs to run to move the stuff around. With a second evaporator, I would guess you will need around 4 cans of 12A (Duracool). Somewhat under 3 with a single evaporator.
Rob Allen
former owner of '76 x-PB
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| Re: AC won't take a charge?? [message #86913 is a reply to message #86881] |
Wed, 02 June 2010 07:35 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
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to make the compressor run with nothing in the system you have to jumper the low pressure switch.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] AC won't take a charge?? [message #86931 is a reply to message #86924] |
Wed, 02 June 2010 09:06 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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I had the compressor jumpered, so it was running.
The problem is it only takes 1/2 a can barely anything.
Then the compressor sounds like it's working REALLY hard, like the pressure is way too high. I mean it loads the engine pretty good!
So whats a good way to figure out if / where the system is plugged?
So far I disconnected the secondary evap and blew through it, so it seems like it not the problem
Is there a better way to check than just disonnecting everything and blowing compressed air through it?
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: AC won't take a charge?? [message #86956 is a reply to message #86881] |
Wed, 02 June 2010 11:25 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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If there is a blockage or bad restriction in the system the high side will have excessive pressure and the low side will be quite low and most likely in a vacuum with the compressor running. Are you certain you don't have a bunch of air in the system this will mess up your pressure readings and load the compressor. In the business it is called non condensibles
Roy.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: AC won't take a charge?? [message #86985 is a reply to message #86956] |
Wed, 02 June 2010 14:56 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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| roy1 wrote on Wed, 02 June 2010 11:25 |
If there is a blockage or bad restriction in the system the high side will have excessive pressure and the low side will be quite low and most likely in a vacuum with the compressor running. Are you certain you don't have a bunch of air in the system this will mess up your pressure readings and load the compressor. In the business it is called non condensibles
Roy.
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Um well actually I do have air in the system...
I thought I read somewhere not to pull a vacuum before charging???
I think Roy may have uncovered my error...
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: AC won't take a charge?? [message #87104 is a reply to message #86985] |
Thu, 03 June 2010 11:24 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Keith
The easiest way to get the system charged from the get go with no surprises is to pull a vacuum then break the vacuum to about 10 lbs pressure with most any refrigerant then release the refrigerant and pull another vacuum do it again release it again then pull a longer vacuum and charge with the refrigerant of choice(R12,134 or duracool). You should weigh in the charge on the money if you know what it is or just be close .Less is better,
then with the engine running around 1500 RPM adjust for your suction pressure somewhere around 20-30 lbs. If it is a warm day and the discharge is rising due to little air flow thru the condenser you may have to mist the condenser with a garden hose while you are adjusting the suction charge. The easiest way to tell if the discharge is high without a gage is the liquid line will be too hot to hold with your hand. of course the suction line will be cold to the touch.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Thu, 03 June 2010 11:35] Report message to a moderator |
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| Re: [GMCnet] AC won't take a charge?? [message #87143 is a reply to message #87104] |
Thu, 03 June 2010 17:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Roy,
I'm curious about why you suggest repeated charge/vacuum cycles?
If you're using an inefficient vacuum pump, I guess it might make sense to
dilute the residual air/H20 as much as possible by repeating the cycle, but
with a reasonably efficient pump -- say 28+ in.Hg -- I can't see a whole lot
of benefit from the extra steps, especially if the final refrigerant is
Duracool/HC12A.
Just a curious novice a/c charger.
Ken H.
On Thu, Jun 3, 2010 at 12:24 PM, roy keen <roynpaula@charter.net> wrote:
> ...
> The easiest way to get the system charged from the get go with no
> surprises is to pull a vacuum then break the vacuum to about 10 lbs pressure
> with most any refrigerant then release the refrigerant and pull another
> vacuum do it again release it again then pull a longer vacuum and charge
> with the refrigerant of choice(R12,134 or duracool). You should weigh in the
> charge on the money if you know what it is or just be close .Less is better,
> ...
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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] AC won't take a charge?? [message #87149 is a reply to message #87143] |
Thu, 03 June 2010 18:10 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Ken
This is standard a/c charging procedure the first couple of vacuum pump times are short the last is the deep vacuum. It is done the same way on large units also. It is good to know there is no air in the system and it only takes another 20 minutes or so to be sure. When I worked on roof top units I usually didn't use a vacuum pump as the system was only open for repairs then charged. Doing it this way you would pressurize it then bring it to just over 0 and do it twice more( the EPA would like all refrigerant recovered). Dealing with air in the system is a call back on a hot day and a nightmare to figure out with out starting over. Another mind boggler is when an idiot tops off a system with the wrong refrigerant.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] AC won't take a charge?? [message #87266 is a reply to message #87149] |
Fri, 04 June 2010 10:24 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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Thanks Roy,
I found a friend with a vacuum pump, hopefully I'll get er done this weekend!
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] AC won't take a charge?? [message #87297 is a reply to message #87266] |
Fri, 04 June 2010 15:31 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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OK well that made NO difference!
I borrowed a nice snapon AC gauge set and pump. Hooked up the gauges and pulled a vacuum for a good hour.
It went all the way down to 30" of vacuum ( ok maybe only 28, but all the way on the bottom of the scale) on the low side and the hogh side was off the scale.
I closed the valves, hooked a can of duracool up, purged the line, opened the valves and let the can fill up the system.
after a few minutes, the low side was at 50 psi as was the high side. Hmmm
So I started the engine, jumpered the AC clutch and the pressure doesn't change, 55 PSI on the low side 50 psi on the high side.
Oh and the output of the compressor that leads to the condenser was too hot to touch.
Remember I have a secondary evap on this thing and this is with 1 can!
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: AC won't take a charge?? [message #87311 is a reply to message #86881] |
Fri, 04 June 2010 17:16 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
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Keith,
Just out of curiosity, what kind of restriction device is on the new secondary evaporator (TXV, orifice tube, etc). I would hate to think that the new evap is unrestricted, which would allow the refrigerant to be pumped through the second evap circuit as fast as the compressor can move it without being able to build pressure.
I assume the original AC worked and you just added another evaporator for added cooling capacity. If so, we can then assume the original TXV is still on the original evap and working correctly.
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: AC won't take a charge?? [message #87317 is a reply to message #87311] |
Fri, 04 June 2010 18:52 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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OK I talked to a guy who knows AC systems and aparently I did a couple things wrong.
1. I charged the system with the can right side up. Duracool/r12a MUST be charged upside down.
2. since the stystem was open I pulled a hard vacuum. when you do this and then charge it, the hydrocarbons strip the oil off of the valves and they don't seal very well. He says to let it sit overnight...
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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