| Dash A/C help [message #134304] |
Tue, 12 July 2011 10:09  |
Gil Slaw
Messages: 69
Registered: May 2006
Location: Hampshire, IL
Karma: 0
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I need a little guidance troubleshooting my dash A/C.
Some cooling is happening, but well below what I expect
I have an aux evaporator "t'd" into the system.
Using Dura-Cool
Engine at operating temperature:
Ambient air temp is 85f
At idle(600 RPM} low is 32psi, high is 130
At 2K RPM low is 20 psi, high is 145psi
Both gauges are steady.
Any suggestions are welcomed
Gil Slaw
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| Re: Dash A/C help [message #134312 is a reply to message #134304] |
Tue, 12 July 2011 10:49  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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You didn't say what the problem is? I prefer the suction a little higher then 20# but Emery will tell you that you are right on. That is if it is blowing cold.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Dash A/C help [message #134325 is a reply to message #134315] |
Tue, 12 July 2011 12:06 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[
Problem: Cooling below my expectation. I get about a 10 degree temp. drop across either evaporator. I am thinking that it should be more like 15.
Gil[/quote]
The air TD at 1500RPM should be more then 20 degrees differential. Do you know how much Duracool is in the system? Is the suction line cold if not you are probably short on your charge add more and note the change. Assuming you are not icing up the evap coil it should get real cold before it goes into the compressor (in the 40'sF) Feel the liquid line before and after the dryer it should be the same temperature if it is colder on the evap side the filter is restricted. I doubt there is air in the system or the discharge would likely be higher.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Dash A/C help [message #134342 is a reply to message #134304] |
Tue, 12 July 2011 12:58 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| Gil Slaw wrote on Tue, 12 July 2011 11:09 |
I need a little guidance troubleshooting my dash A/C.
Some cooling is happening, but well below what I expect
I have an aux evaporator "t'd" into the system.
Using Dura-Cool
Engine at operating temperature:
Ambient air temp is 85f
At idle(600 RPM} low is 32psi, high is 130
At 2K RPM low is 20 psi, high is 145psi
Both gauges are steady.
Sir: There is a chance that the water going to the heater box is not shut off and adding heat to the dash air. Do you have a manual valve or the stock vacuum valve? If stock check to see if the lever moves when going to AC. If not check for vacuum and replace if necessary. It also might be the blend door?? Of course I`m only guessing..
Any suggestions are welcomed
Gil Slaw
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C. Boyd
76 Crestmont
East Tennessee
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| Re: Dash A/C help [message #134344 is a reply to message #134342] |
Tue, 12 July 2011 13:00 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| C Boyd wrote on Tue, 12 July 2011 13:58 |
| Gil Slaw wrote on Tue, 12 July 2011 11:09 |
I need a little guidance troubleshooting my dash A/C.
Some cooling is happening, but well below what I expect
I have an aux evaporator "t'd" into the system.
Using Dura-Cool
Engine at operating temperature:
Ambient air temp is 85f
At idle(600 RPM} low is 32psi, high is 130
At 2K RPM low is 20 psi, high is 145psi
Both gauges are steady.
Sir: There is a chance that the water going to the heater box is not shut off and adding heat to the dash air. Do you have a manual valve or the stock vacuum valve? If stock check to see if the lever moves when going to AC. If not check for vacuum and replace if necessary. It also might be the blend door?? Of course I`m only guessing..
Any suggestions are welcomed
Gil Slaw
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Also you said you have an auxillary evaporater, it does have its own expansion valve??
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Dash A/C help [message #134345 is a reply to message #134336] |
Tue, 12 July 2011 13:03 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| emerystora wrote on Tue, 12 July 2011 13:32 |
> [
> Problem: Cooling below my expectation. I get about a 10 degree temp. drop across either evaporator. I am thinking that it should be more like 15.
>
> Gil[
>
You should have a lot more than a 20 deg differential across the evaporator. I am thinking more like 40 deg or so.
With the engine operating at 1500 RPM and the air conditioner on high, measure the low side pressure (don't worry about the high side).
it should he about 20 psi. If it is lower than that add a little Duracool. If it is more than that, bleed off a little.
Let us know what you find.
Emery Stora
77 Kingsley
Santa Fe, NM
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Emery: I have a basic question please. Which scale do you use for durocool? My gauges have 4 scales and 20 is different on each scale? This is confusing to me? I have no formal AC training.
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Dash A/C help [message #134346 is a reply to message #134336] |
Tue, 12 July 2011 13:14 |
Gil Slaw
Messages: 69
Registered: May 2006
Location: Hampshire, IL
Karma: 0
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| emerystora wrote on Tue, 12 July 2011 12:32 |
> [
> Problem: Cooling below my expectation. I get about a 10 degree temp. drop across either evaporator. I am thinking that it should be more like 15.
>
> Gil[
>
You should have a lot more than a 20 deg differential across the evaporator. I am thinking more like 40 deg or so.
With the engine operating at 1500 RPM and the air conditioner on high, measure the low side pressure (don't worry about the high side).
it should he about 20 psi. If it is lower than that add a little Duracool. If it is more than that, bleed off a little.
Let us know what you find.
Emery Stora
77 Kingsley
Santa Fe, NM
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Emery,
Good news and bad news!
Note that I have about 8 ft more hose than stock plus a second small evaporator next to the copilot's seat.
I don't know how much Duracool is in the system.
The suction line seems very cool, but not really cold, I could not get a good temp reading on it. It is not frosted, and the humidity is 60 here
I added 1 full can and at 1500 RPM I now measure a 20 degree drop giving a 70 degree reading. Low pressure went to a little over 30 and high now is 190.
Looks like some progress but I'm hoping for more.
Gil
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| Re: [GMCnet] Dash A/C help [message #134358 is a reply to message #134346] |
Tue, 12 July 2011 14:01 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Why did you add a full can? Don't worry about the differential temperature across the evaporator or the high pressure side. Just concentrate on the low pressure at 1500 RPM. If you now have 30 psi then you have too much Duracool in. Duracool works differently than you expect. The lower the low side pressure the colder the system gets. I once ran mine at 15 psi and it was so cold that the evaporator froze up because the condensation turned to a block of ice and then I got no air flow through the evaporator. When I increased the charge to 20 psi all was fine.
My system also has extra hose and a large second evaporator but my system still only takes about 3 cans total. The extra hoses and extra evaporator fill up with vapor, not liquid, so it doesn't take very much to fill them.
Most GMCs that I have filled take a little less than 3 cans. If there is an extra evaporator then it might take 3 full cans but I would not think it would be any more.
I suggest that you slowly bleed off a little and you should see it get colder.
I already told you this in my last email but you seem to have done the opposite and added more Duracool
Emery Stora
On Jul 12, 2011, at 12:14 PM, Gil Slaw wrote:
>
>
> emerystora wrote on Tue, 12 July 2011 12:32
>>> [
>>> Problem: Cooling below my expectation. I get about a 10 degree temp. drop across either evaporator. I am thinking that it should be more like 15.
>>>
>>> Gil[
>>>
>>
>> You should have a lot more than a 20 deg differential across the evaporator. I am thinking more like 40 deg or so.
>> With the engine operating at 1500 RPM and the air conditioner on high, measure the low side pressure (don't worry about the high side).
>> it should he about 20 psi. If it is lower than that add a little Duracool. If it is more than that, bleed off a little.
>>
>> Let us know what you find.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> Emery,
>
> Good news and bad news!
>
> Note that I have about 8 ft more hose than stock plus a second small evaporator next to the copilot's seat.
>
> I don't know how much Duracool is in the system.
>
> The suction line seems very cool, but not really cold, I could not get a good temp reading on it. It is not frosted, and the humidity is 60 here
>
> I added 1 full can and at 1500 RPM I now measure a 20 degree drop giving a 70 degree reading. Low pressure went to a little over 30 and high now is 190.
>
> Looks like some progress but I'm hoping for more.
>
> Gil
>
>
Emery Stora
77 Kingsley
Santa Fe, NM
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| Re: [GMCnet] Dash A/C help [message #134489 is a reply to message #134345] |
Wed, 13 July 2011 17:27 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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Senior Member |
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| C Boyd wrote on Tue, 12 July 2011 13:03 |
| emerystora wrote on Tue, 12 July 2011 13:32 |
> [
> Problem: Cooling below my expectation. I get about a 10 degree temp. drop across either evaporator. I am thinking that it should be more like 15.
>
> Gil[
>
You should have a lot more than a 20 deg differential across the evaporator. I am thinking more like 40 deg or so.
With the engine operating at 1500 RPM and the air conditioner on high, measure the low side pressure (don't worry about the high side).
it should he about 20 psi. If it is lower than that add a little Duracool. If it is more than that, bleed off a little.
Let us know what you find.
Emery Stora
77 Kingsley
Santa Fe, NM
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Emery: I have a basic question please. Which scale do you use for durocool? My gauges have 4 scales and 20 is different on each scale? This is confusing to me? I have no formal AC training.
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i looked at my gauges today that are made for R134A. the inner most scale is actual # reading. the outer scales show readings for different freons.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] Dash A/C help [message #134502 is a reply to message #134489] |
Wed, 13 July 2011 19:03 |
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ahhh! This helps!
www.central-air-conditioner-and-refrigeration.com/hvac_gauges.html
Google is still my friend.
bdub
On Wed, Jul 13, 2011 at 5:27 PM, fred veenschoten <fredntoni@cox.net> wrote:
Which scale do you use for durocool? My gauges have 4 scales and 20
is different on each scale?
>
> i looked at my gauges today that are made for R134A. the inner most scale is actual # reading. the outer scales show readings for different freons.
>
> --
> Fred V
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bdub
bdub.net
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| Re: [GMCnet] Dash A/C help [message #134503 is a reply to message #134489] |
Wed, 13 July 2011 19:09 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[ looked at my gauges today that are made for R134A. the inner most scale is actual # reading. the outer scales show readings for different freons.
[/quote]
Don't worry about the different scales they just tell you what the refrigerant temperature is for each refrigerant at that pressure.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Dash A/C help [message #134511 is a reply to message #134304] |
Wed, 13 July 2011 20:20 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Dumb question......is your fan clutch OK?? Even when not locked up due to high temp, on the driveway you should be getting a pretty stiff wind being drawn through the grill. If shot, the freewheeling mode can be too free wheeling to provide base lavel air flow though the condensor.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Dash A/C help [message #134518 is a reply to message #134509] |
Wed, 13 July 2011 21:04 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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This might be what your after:
http://www.foxtoolsupply.com/HC-12a.htm
J.R. Wright
GMC GreatLaker
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Jul 13, 2011, at 9:01 PM, D C *Mac* Macdonald wrote:
>
> Is there a T/P (Temperature/Pressure) chart/table around for Dura-
> Cool?
>
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> ~~ ~ D C "Mac" Macdonald ~ ~~
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Dash A/C help [message #134533 is a reply to message #134511] |
Wed, 13 July 2011 21:56 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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| JohnL455 wrote on Wed, 13 July 2011 18:20 |
Dumb question......is your fan clutch OK?? Even when not locked up due to high temp, on the driveway you should be getting a pretty stiff wind being drawn through the grill. If shot, the freewheeling mode can be too free wheeling to provide base lavel air flow though the condensor.
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Not a dumb question at all. If it is a warm day and the liquid line is getting too hot to touch a mist from a garden hose on the condenser is a good idea. It would also lower the high&low side pressures.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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