A/C High Pressure switch leaking

[bdkee]

Hi all,

I've got a 91 Vanagon GL with an A/C system that has been converted to R134. The condenser up front sprung a leak last week after being hit by a rock or some other debris. I swapped that out for a new unit and then refilled the system filling from the low side. I do not have a high side gauge so I didn't touch it. It took two and a half small bottles of refrigerant and blew cold. After a day though I lost about 15psi and it stopped blowing cold. I added another can and then discovered that the high pressure switch was leaking out of the backside where the wires come out.

Do you think that I just need to replace that switch or should I have done something on the high side that may have kept it from building up too much pressure and blowing the seal on the switch?

Thanks as always.

Brian

[Terry Kay]

This is exactly why,when loading up any AC system you need a high pressure gauge so you don't overload it.

Maybe you smoked the valve -- who knows?

Change the leaking switch with a new one, & reload.

This is the down side of using The Wally World jippo reloading kits.
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T.K.

[bdkee]

Hi T.K.,

That's kinda what I figured. Just making sure I wasn't inhaling too many fumes and missing something (even more) obvious.

Thanks for the advice. Off to order up a new switch and proper gauges.

Brian

[Sir Sam]

Harbor freight has inexpensive guage sets and vacuum pumps. Served me well for years.

If you unscrew the switch there is a Schrader valve in the line that should hold the pressure in.

Did you pull a vacuum before refilling?
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'91 Carat Westy

87' Syncro + '87 Westy conversion coming soon

[Terry Kay]

What a Perfect---- opportunity to load your system up with refrigerant that will actually work well.

Re load with Red Tek.
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T.K.

[bdkee]

I'll check out the Red Tek. How much will I need to refill the system?

As to the question about vaccum lines, no, I did not remove any. Is there a vaccum line to remove on the C-pillar near the pressure switch?

[Terry Kay]

No, you weren't asked about a vacuum line.

I'll ask this one again;

Did you suck the AC system down into a hard vacuum prior to introducing the 134-a you used, or did you just fix the condenser and let the 134 fly?

You must totally evacuate the system first, or deem the work you've just done worthless.
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T.K.

[bdkee]

Got it and no, I didn't pull a vacuum as I assumed that opening the system up to change the condenser would have evacuated the system. See what happens when I assume?! I'll find a post on the proper procedure and go from there.

Cheers

Brian

[Terry Kay]

You did evacuated the system---if there was any freon left in it.

You must pull a hard vacuum to evacuate any moisture out of the system, and see how long it'll hold it---to make sure it's good & tight.

Then load it up.
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T.K.

[dobryan]

Lots of good reading here....

http://www.thesamba.com/vw/forum/viewtopic.php?t=292488&highlight=redtek
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[redeyeksc]

Before wasting time on a vacuum, do a pressure test with dry nitrogen. Leave it in for half hour. This will not only tell you if there is a leak but it will also help with the evacuation process later by drawing out the moisture.

Although not required you should pull the system down with a vacuum pump to 500 microns. It should hold below 1100 microns, with the pump off, if it doesn't and goes above 1500 chances are there is still a small leak somewhere.If it doesn't go above 1500 there is still moisture in the system and needs more time with the vacuum pump.

For a long life of your A/C and it's components this procedure is a must, anything else is just guessing.

As a licensed refrigeration mechanic I have to admit, products like Redtek scare the crap out of me. Hydrocarbon refrigerants tend to not be properly labeled for future mechanics working on the system. I highly recommend finding someone with the proper tools and knowledge to do the job, you won't regret it.
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84 Westfalia, now with Bostig Zetec 2.0L, Manual Transmission
Alex

[Terry Kay]

Pulling the system down with a vacuum pump is plenty good pulled down to 29--30 hg.
for every 100 ft above sea level the vacuum gauge must be corrected by 1 inch of Hg. to be on the money.

If your between 950 & 1050 ft above sea level the gauge should be reading 28.5 hg, and will be the same as 29.5 hg.

These readings are what you should be looking at & seeing on the low pressure gauge.

This is the standard of evacuation proceedures, & measurements and you can delete the nitrogen caper--nobody in the trade uses that.

You must have a decent evac pump to get to these evac pressures efficiantly.
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T.K.

[redeyeksc]

Do as you would like, my information is the proper way to do the job. Because not everyone does it, does not mean that they are doing it correct. To pull a proper vacuum you must measure it with a micron gauge. Measuring in Hg will not tell you if there is moisture present, and will not tell you if there is a leak. Will what others are recommending to you work? Probably.

Like anything, do your research, make an informed decision.

To get you started here is a good write up:

http://www.trutechtools.com/Vacuum-Training_c_1100.html
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84 Westfalia, now with Bostig Zetec 2.0L, Manual Transmission
Alex

[Farf]

I'm with redeyeksc on this one. The use of nitrogen and micron gauges is the standard in the HVAC industry and I haven't seen technicians not using them for quite a while. It took me a few years to join the micron gauge/nitrogen bandwagon, but I'm glad I did as it took the guesswork work out of system diagnosis. Can't imagine not using them today.

[dobryan]

[Terry Kay]

Here is the instructions direct out of an Industry standard Mitchell's Automotive AC Manual;

"At altitudes higher than sea level, it will not be possible to obtain a vacuum reading of 29.5 inches of HG, on the low side coumpound gauge.
For each 1000 feet of altitude, the vacuum gauge must be corrected by 1 inch of HG, to comprensate for the change in atmospheric pressure.
For example, at an altitude of between 950 and 1,050 feet, a gauge reading of 28.5 inches of HG. will be the same as a gauge reading of 29.5 inches of HG. at sea level. When this vacuum is reached approximatly 30 minutes should be allowed in evacuating the system to ensure complete moisture removal."

This is right from the industry standards mouth, it has worked quite well for me since 1961, and has never failed, in automotive, Truck , heavy equipment operating levels.
Don't complicate a basic AC theory of operation.

I have tried to make it simple for the babes in the woods here who don't have a clue how an AC system is supposed to operate, how to get it up and running in the easiest ways without complicating the issue.

You guys in the HVAC department huffing on the nitrogen bottles may do as you wish.
There is nothing mentioned anywhere in any period correct Industry Standard AC manuals mentioning nitrogen use, and that's the way it's gonna stay here.
Keep it simple and period correct stupid.

I try and always have tried to make it easy here and has been working quite well up until yesterday.
Don't toss flies in the pie, don't try and complicate something that isn't at all complicated.

I suggest often that these kids purchase a AC Basic training manual to explain & give them an easy comprehesion of automotive AC operation & repair.
It would make all of this a hell of a lot easier, but they are saving a buck, and still have no idea where in the heck they are going.

Penny wise--pound foolish.
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T.K.