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System won't vacuum down

Fishypete on Wed April 01, 2009 11:47 PM User is offline

Year: 1992
Make: Toyoya
Model: Paseo
Engine Size: 1.5
Refrigerant Type: R134

I seem to have a serious problem. I have tried to vacuum down my Air Conditioning system after a total overhaul....everything has been changed except the lines and hoses. New rem compressor, evaporator, condensor, 134 expansion valve and drier and obviously new O-rings. The reason I replaced everything is age... and to change over from R12 to R134, the only problem prior was the evaporator...no compressor failure. When I tried to vacuum down the system, used a Mastercool 1.5 CFM vacuum pump, all I could get was appx 15 on the gauge....and that was after a couple hours.

I have checked the lines and other parts for a leak...used Pag46 with dye...couldn't find a leak....the only place I haven't checked is the evaporator...so should I state the obvious?

Question...I live in Florida appx 15 feet above the water...could being on sea level effect my reading? Could the R134 expansion valve be causing the problem?

I'm using a new set of Robinair gauges and hoses.

Any suggestions?

Thanks;

Peter Giacometti

Chick on Thu April 02, 2009 5:18 AM User is offlineView users profile

Did you make sure your gauges are “zeroed before pulling your vacuum? There is a set screw in the gauge to do this. Also, when you shut the pump off and isolate the system, does it go right back to zero or hang at the 10hg you pulled. You might want to pressurize the system to aid in finding the leak if the gauge set is accurate. Hope this helps..

PS: Sea level should read 29.9hg, you lose one HG of vacuum for every 1000 feet above sea level..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Fishypete on Thu April 02, 2009 9:34 AM User is offline

The gauges are set at zero....and when I shut the pump off, they immediately rise to that level and do not hold a vacuum. At first I thought I had a blockage...so I shot air thru the lines....first from the low side and then from the high side...both times I had air coming out from the opposite line...so I have to think it's not a blockage problem. I also thought perhaps it could be a schrader valve from the new conversion fitting, but I would think even if the valve didn't open...the lines from the gauges would vaccum down more than 15. I even changed the vaccum pump oil to see if that was the reason with no change....and when I did change the pump oil, it had some dye in it, which led me to believe it wasn't the valve.

Thanks;

Peter

Edited: Thu April 02, 2009 at 9:41 AM by Fishypete

mk378 on Thu April 02, 2009 11:03 AM User is offline

See if you can get a full vacuum just in the manifold and hoses -- not connected to the car.

Vacuum pumps typically do not sustain vacuum while the motor is not running. To do a "leak up" check, evacuate the system, then close both hand valves on the manifold to isolate the yellow hose and pump. The gauges will continue to read the pressure in the car. Then you can switch the pump off if you want.

Fishypete on Thu April 02, 2009 11:57 AM User is offline

I believe I already tried that. After reaching the 15 mark on the low side gauge after a couple of hours...I shut both manifold hand valves, shut the vacuum pump off and the reading's on the gauges went to zero immediately. I was using a rental vacuum pump and since brought it back. My friend has one of the vacuum pumps that uses compressed air...would that work?

Should I have changed the tube assy also when I changed the evaporator? It didn't appear to be a problem when I looked at it...but looks can be deceptive.

Thanks;

Peter

dasinc on Thu April 02, 2009 5:08 PM User is offlineView users profile

If it's going down to zero immediately you have a large leak somewhere in the system. Sometimes larger vacuum leaks like that can actually be heard while the pump is pumping down. It's most likely not your gauges but if you haven't done what mk378 suggested you should. In a sealed system most vacuum pumps will have your vacuum down to 15-20 hg in a matter of minutes. The next thing to do would be to pressurize the system, preferably with nitrogen because it's a dry gas. If you have to you can use compressed air, but after the leak is found and sealed you'd want to pull a real good vacuum to burn out any extra moisture that it put into the system. Are you sure that an oring didn't fall off of one of your fittings as you were putting it together? Again, pressurize it and you'll find it.

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Take care,

Travis

[email protected]

Chick on Thu April 02, 2009 6:01 PM User is offlineView users profile

Even if you try to charge the system, a leak that big is going to show pretty fast, so pressurize the system, with nitrogen or refrigerant.. listen close, you should here it..It could even be a bad high pressure pop off valve on the compressor, an O ring that didn't seal properly..let us know what you find..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Dougflas on Thu April 02, 2009 8:02 PM User is offline

Those vacuum pumps that are run by air are not even good as boat anchors.

JJM on Thu April 02, 2009 8:48 PM User is offline

I'm with Chick and the others here... gotta be a pretty large leak, like the pressure relief valve, o-ring(s), or something.

I doubt the evap would have a leak that large, but if you want to be sure, disconnect it, cap off the hoses leading to it, and try to vacuum down the system again. If it holds, the o-rings to the evap were leaking or the evap itself is bad. You can also try pulling a vacuum just on the evap.

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com



Fishypete on Fri April 03, 2009 10:42 AM User is offline

I will try what you suggest. I have ordered another O-ring set and a drier, from AMAI...and also a new tube assy for the Evaporator. When I find the problem, I'll post back.

Thanks;

Peter

TRB on Fri April 03, 2009 10:53 AM User is offlineView users profile

Quote
Originally posted by: Fishypete
I will try what you suggest. I have ordered another O-ring set and a drier, from AMAI...and also a new tube assy for the Evaporator. When I find the problem, I'll post back.

Thanks;

Peter

Thanks for the support, keep us posted!



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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Fishypete on Sat April 04, 2009 4:09 PM User is offline

Alert..Alert..Alert....sorry I couldn't help myself.


Well I found the leak, After disconnecting the lines going into the evaporator...and then as best as I could plugging the outside lines, I vacuumed down the system to slightly less than 29. Considering it wasn't a great seal...that ain't bad!

So as soon as I receive the parts on order....hopefully next weekend I will fix the problem with either the evaporator or the tube assy....and then perhaps I can say...let there be air!!

Since I've had this problem and I have to open up the system again...I think it best to do a full vacuum three times...before I place any R134 into the system...do you agree?

Thanks;

Peter

Edited: Sat April 04, 2009 at 4:09 PM by Fishypete

Fishypete on Thu April 09, 2009 12:53 PM User is offline

Well here's one for the books...I assume anyway. I have taken the Evaporator assy apart, and to my disgust...the flange on the evaporator isn't straight and makes the expansion valve uneven....hence the leak. I have just purchase a new evaporator from AMA Inc. If I don't lose my mind...like my money...LOL...I'll let you know what happens when I receive the new evaporator and put every thing together and test it.

Thank again;

Peter

TRB on Thu April 09, 2009 9:44 PM User is offlineView users profile

Keep us posted and thanks for supporting the forum and AMA. Only way we can keep things going around here as we did not receive any "stimulus" money!

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Fishypete on Fri April 10, 2009 7:13 PM User is offline

Mission Accomplished!!

We have AIR!

Changed the evaporator....same problem even though the other evaporator was screwed up...took it apart and changed the only other item that I didn't try changing again...the R134 Expansion valve....problem solved. For whatever reason...the R134 expansion valve wouldn't work...thanks anyway AMAI.

At 2000 rpm's the temp is 45, at appx 900 rpm's...it's 53 it was 82 today. Pressures are within norms...and I used 24 ozs of Dupont 134.

I don't have to tell you what living in a hot state is like, FLORIDA for me....this wasn't easy for a 57 year old with Arthritis...but with patience and a few chosen words...LOL..I completed the task.

Thank you for your assistance and products.!

Peter Giacometti

Edited: Fri April 10, 2009 at 7:16 PM by Fishypete

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