A/C low pressure port showing slight vacuum

[fastartcee]

I have a 1995 Flair motorhome (Chevy chassis). My a/c hasn't been working for years (and has been left 'off'), but we're headed to a hot spot so I thought I'd get it operating again. I used a Red Tek kit, adding one can of refrigerant and one can of Red Tek oil treatment.

With the engine off, I have about 45 psi at the low pressure port. With the engine running, and the a/c on, my gauge actually shows a few psi of vacuum, and I'm not getting any cooling. If I turn the engine off, the gauge shows about 45 psi again.

I don't understand what could be happening that could be causing a vacuum at the low pressure port. Any help would be much appreciated!

Art

[GM Tech]

is it 45 degrees where you are at? Static pressure (engine off) should be nearly the same as ambient temp - so this tells me you are incredibly short, or shy on refrigerant- like maybe only a few ounces have been sucked in...Running in a vacuum also confirms this. A typical a/c system will hold 2 or more pounds- so figure it up, a red tek can is what 12 ounces, you'll need maybe 3 total....before you can test for cooling.....but it looks like you have a pretty big leal if you put one whole can in and you are reading only 45 psi static.....because that would relate to about 3 ounces in the system.....

[fastartcee]

is it 45 degrees where you are at? Static pressure (engine off) should be nearly the same as ambient temp - so this tells me you are incredibly short, or shy on refrigerant- like maybe only a few ounces have been sucked in...Running in a vacuum also confirms this. A typical a/c system will hold 2 or more pounds- so figure it up, a red tek can is what 12 ounces, you'll need maybe 3 total....before you can test for cooling.....but it looks like you have a pretty big leal if you put one whole can in and you are reading only 45 psi static.....because that would relate to about 3 ounces in the system.....

Thanks for the reply. It's about 30 C (85 F) here. So with a proper charge, what should the static pressure be?

I have another can (Red Tek 12A -- 6 oz), plus a can of Red Tek water treatment (Dry 12 -- 2 oz refrigerant) and a can of Red Tek leak treatment (ProSeal 12 -- 2 oz refrigerant). If I were to inject all three, it would mean a total charge of nearly 3 cans. Any advice on doing this would be much appreciated. I'll monitor the forum for a day or two before I do anything.

Again, thanks!

Art

[bohica2xo]

I did not see where you pulled a vacuum on the system before charging. What was the system static pressure before you put the propane in it?

I would avoid adding any "secret sauce" that came from a kit. Sealer can be more trouble than an actual repair.

Is there no 134a available at your location?

[Jag987]

No one here (that I am aware of) is going to tell you to put in leak stop of any sort. The proper thing to do is find the leak, repair it, then recharge it. Because you are using 12A (basically propane), I'm going to assume you are in Canada or somewhere else where you cannot purchase 134a without a license. Anyway, if all the refrigerant has leaked out, it should not be hard to find the leak with what you have already put in. Soapy water in a spray bottle is my favorite way to find leaks, just start spraying the lines and components until you find bubbles.

[fastartcee]

No one here (that I am aware of) is going to tell you to put in leak stop of any sort. The proper thing to do is find the leak, repair it, then recharge it. Because you are using 12A (basically propane), I'm going to assume you are in Canada or somewhere else where you cannot purchase 134a without a license. Anyway, if all the refrigerant has leaked out, it should not be hard to find the leak with what you have already put in. Soapy water in a spray bottle is my favorite way to find leaks, just start spraying the lines and components until you find bubbles.

Jag987, I particularly like your tag line... "I bought a kit, now I'm an expert".

I haven't sorted out my issue, but I've decided that a rank amateur should not be messing around with dangerous chemicals and a complex system. So... if my a/c is going to get fixed, I'll pay to have it done by a professional.

Thanks to all for your replies.

Art
Ex-a/c-amateur

[Jag987]

The thing about this forum is if you are patient, willing to listen and do as suggested, there are people here who are willing to help. I have come across many of the same problems I have read about here. I have gone back to old thread and found solutions to problems. If you want to keep going with this on your own, please stick around. Just be prepared and willing to take it to someone for some testing and refrigerant recovery.

Good luck!