AC questions... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Alex Hayley · 04-16-2002, 09:06 AM

It is about that time of the year to get the AC working. Can someone tell me how I would go about pulling a vacumm on the AC system? It has not worked since I got the truck(a couple years ago) so I am figuring I need to evacuate the system. Also, from what I can gather, if I pull a vacumm and hold it for a while you can tell if there is a leak in the system. Am I correct?

Thanks...

Hutch · 04-16-2002, 09:28 AM

YES,
You would use a vacuum pump, Most shops that do auto repair have one. After pulling a vacuum I understand that you need to let it sit for at least 30 min to see if there is any leakage.
You need to be careful when working with R-12
there are alot of procedures that the EPA requires which just seem to make the repair prices go up.
I would think that you are on the right track
Be sure and get the system as tight as possible before investing in all the expendable parts(dryer,expansion valve,etc.)

------------------
John Hutchison
Grapevine,Texas
76051
71 1/2 ton swb 307 pg
69 Jaguar XK-E 4.2 Roadster

Frank_Zeller · 04-16-2002, 09:37 AM

If you have access to a Nitrogen tank with pressure regulator you can rig it up to pressurize the system to about 50 psi then use a liquid with soap the shows bubbles from the leaks on all the lines and components.

Alex Hayley · 04-16-2002, 09:39 AM

If I was going to do this work myself where might I find a vacumm pump? I actually have two vehicle(72 chev and 97 VW) with the AC not working so I figure I will learn how to do it myself and save some money.

Hutch · 04-16-2002, 11:00 AM

Try this,
Looks cheap enough who knows it might work for you http://ww2.harborfreight.com/cpi/cta...temnumber=3952

HuggerCST · 04-16-2002, 11:21 AM

You will need another set of guages for the '97 VW. I believe all vehicles '94 and newer use R-134, which takes special guages. You can use the same vac. pump though.

Frank_Zeller · 04-16-2002, 01:08 PM

these guys also sell the 134A to R12 gauge adapters and new gauges.
http://www.duracoolusa.com/

Vince M · 04-16-2002, 03:13 PM

Alex,

I'm going through exactly the same thing myself. I've been looking at swap meets and found a set of used gauges. Check out eBay for a pump. There's a bunch of them there. Robinair makes some stuff for AC service. I've gone to their web site and learned a few things. There's other makes out there also which look to be pretty good. eBay will give you a good idea on market prices.

------------------
Orlando,FL
72 Chevy 4x4 3/4T CustomCamper w/SB 406

Alex Hayley · 04-17-2002, 07:56 AM

Vince,

In the event that you check this thread again, it looks like the vacumm pump on ebay is the same as mentioned above(http://ww2.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952
) only the one at harbour freight is less money. At least that is what is looks like.

Alex

ebfabman · 04-17-2002, 08:18 AM

Guys, AC pumps and gauge sets are like batteries and tires, not something you really want to buy used.
Been a cerified auto air tech for about 20 years and seen lots of vac pumps that didn't work and lots of gauge sets that looked ok but didn't work properly or not at all.

ONLY BUY USED AC TOOLS IF YOU KNOW THE SOURCE!

DennyB · 04-17-2002, 11:56 AM

Alex Hayley is correct.
Don't buy the Central Pnumatic Air Vacuum Pump from Ebay.
Harbor freight has them for $9.99 and actually there on sale for $8.99 now

Vince M · 04-17-2002, 07:40 PM

ebfabman has some good advice. Be carefull buying used stuff. The vacuum pumps I was looking at were a lot more than $8.99.
At swap meets it easy to find an outlet and plug 'em in before buying them but eBay etc.. makes that kind of hard to do. I take the price into consideration when buying used.
I've seen an old refigeration compressor used as a vacuum pump if you have access to an old refrigerator and don't mind gutting it. Of course that would release Freon into the atmosphere..not such a good idea these days.

------------------
Orlando,FL
72 Chevy 4x4 3/4T CustomCamper w/SB 406

DennyB · 04-18-2002, 12:58 PM

Vince,
That is a great idea!
I've got an old compressor that the pump is shot but motor and tank is good.
and an old refrigerator that has a good compressor.
I have to get the freon removed to dispose it anyway.
Put the 2 together and I have a A/C vacuum pump and a power brake bleeder!
Thanks for the idea!!
Denny

04-16-2002, 09:06 AM	#1
Alex Hayley Registered User Join Date: Jul 2000 Location: NC Posts: 987	AC questions... It is about that time of the year to get the AC working. Can someone tell me how I would go about pulling a vacumm on the AC system? It has not worked since I got the truck(a couple years ago) so I am figuring I need to evacuate the system. Also, from what I can gather, if I pull a vacumm and hold it for a while you can tell if there is a leak in the system. Am I correct? Thanks...

04-16-2002, 09:28 AM	#2
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	YES, You would use a vacuum pump, Most shops that do auto repair have one. After pulling a vacuum I understand that you need to let it sit for at least 30 min to see if there is any leakage. You need to be careful when working with R-12 there are alot of procedures that the EPA requires which just seem to make the repair prices go up. I would think that you are on the right track Be sure and get the system as tight as possible before investing in all the expendable parts(dryer,expansion valve,etc.) ------------------ John Hutchison Grapevine,Texas 76051 71 1/2 ton swb 307 pg 69 Jaguar XK-E 4.2 Roadster __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

04-16-2002, 09:37 AM	#3
Frank_Zeller Registered User Join Date: Jun 2001 Location: Austin, Texas Posts: 796	If you have access to a Nitrogen tank with pressure regulator you can rig it up to pressurize the system to about 50 psi then use a liquid with soap the shows bubbles from the leaks on all the lines and components. __________________ 69 SWB C/10 5-6 drop 700R4 69 Firebird Convert 455 4 spd 70 Torino GT Convert Austin-Texas

04-16-2002, 11:00 AM	#5
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	Try this, Looks cheap enough who knows it might work for you http://ww2.harborfreight.com/cpi/cta...temnumber=3952 __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

04-16-2002, 11:21 AM	#6
HuggerCST Registered User Join Date: Jul 2001 Location: North Louisiana Posts: 4,501	You will need another set of guages for the '97 VW. I believe all vehicles '94 and newer use R-134, which takes special guages. You can use the same vac. pump though. __________________ Wynne 70 CST short fleet Hugger orange & white, 350/350, ps, pb, air, tilt, tach/vac/speedwarning, original buckets, AM/FM, oak bed floor, shoulder belts, 3.5"/5.5" drop, 20" American Racing VN425s. Build thread 53 Chevy shortbed 69 Camaro Click here to subscribe Chevy GMC International Truck Club Louisiana Charter Member http://www.louisianaclassictruckclub.com

04-16-2002, 09:39 AM	#4
Alex Hayley Registered User Join Date: Jul 2000 Location: NC Posts: 987	If I was going to do this work myself where might I find a vacumm pump? I actually have two vehicle(72 chev and 97 VW) with the AC not working so I figure I will learn how to do it myself and save some money.

04-16-2002, 01:08 PM	#7
Frank_Zeller Registered User Join Date: Jun 2001 Location: Austin, Texas Posts: 796	these guys also sell the 134A to R12 gauge adapters and new gauges. http://www.duracoolusa.com/ __________________ 69 SWB C/10 5-6 drop 700R4 69 Firebird Convert 455 4 spd 70 Torino GT Convert Austin-Texas

04-16-2002, 03:13 PM	#8
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	Alex, I'm going through exactly the same thing myself. I've been looking at swap meets and found a set of used gauges. Check out eBay for a pump. There's a bunch of them there. Robinair makes some stuff for AC service. I've gone to their web site and learned a few things. There's other makes out there also which look to be pretty good. eBay will give you a good idea on market prices. ------------------ Orlando,FL 72 Chevy 4x4 3/4T CustomCamper w/SB 406 __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.

04-17-2002, 07:56 AM	#9
Alex Hayley Registered User Join Date: Jul 2000 Location: NC Posts: 987	Vince, In the event that you check this thread again, it looks like the vacumm pump on ebay is the same as mentioned above(http://ww2.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952 ) only the one at harbour freight is less money. At least that is what is looks like. Alex

04-17-2002, 08:18 AM	#10
ebfabman Registered User Join Date: Nov 2001 Location: Concord, NC Posts: 2,488	Guys, AC pumps and gauge sets are like batteries and tires, not something you really want to buy used. Been a cerified auto air tech for about 20 years and seen lots of vac pumps that didn't work and lots of gauge sets that looked ok but didn't work properly or not at all. ONLY BUY USED AC TOOLS IF YOU KNOW THE SOURCE!

04-17-2002, 11:56 AM	#11
DennyB Led Sled! Discs R 4 ME! Join Date: Jan 2001 Location: Toms River, NJ, USA (Transplanted Hoosier) Posts: 7,327	Alex Hayley is correct. Don't buy the Central Pnumatic Air Vacuum Pump from Ebay. Harbor freight has them for $9.99 and actually there on sale for $8.99 now __________________ "Never ride faster than your Angel can fly" I.M.O.M,W,J&C Patriot Guard Rider

04-17-2002, 07:40 PM	#12
Vince M Senior Member Join Date: Apr 2000 Location: Orlando, FL Posts: 1,076	ebfabman has some good advice. Be carefull buying used stuff. The vacuum pumps I was looking at were a lot more than $8.99. At swap meets it easy to find an outlet and plug 'em in before buying them but eBay etc.. makes that kind of hard to do. I take the price into consideration when buying used. I've seen an old refigeration compressor used as a vacuum pump if you have access to an old refrigerator and don't mind gutting it. Of course that would release Freon into the atmosphere..not such a good idea these days. ------------------ Orlando,FL 72 Chevy 4x4 3/4T CustomCamper w/SB 406 __________________ ............................................................ 68 Chevy CST SWB w/LS1, carb & 700r4. Golden Anniversary clone with a few improvements.

04-18-2002, 12:58 PM	#13
DennyB Led Sled! Discs R 4 ME! Join Date: Jan 2001 Location: Toms River, NJ, USA (Transplanted Hoosier) Posts: 7,327	Vince, That is a great idea! I've got an old compressor that the pump is shot but motor and tank is good. and an old refrigerator that has a good compressor. I have to get the freon removed to dispose it anyway. Put the 2 together and I have a A/C vacuum pump and a power brake bleeder! Thanks for the idea!! Denny __________________ "Never ride faster than your Angel can fly" I.M.O.M,W,J&C Patriot Guard Rider



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