OT: Nissan AC

Post by **Legacy777** » Fri Oct 29, 2004 12:08 am

I decided to check the nissan's ac, since I was messing with mine today. Something is definitely not right because it cylces too much. I stuck the gauges on, and the low side is around 45. The high side is crazy. It's like 280!

Does that mean it's overcharged, or what's goin on?

I really don't like ac systems.

vrg3 · Post by **vrg3** » Fri Oct 29, 2004 1:41 am

I think that low side pressure is a bit high, too.

This could be an overcharge...Or some kind of clog on the high side, I think.

Or it could be "normal" if the system's charged with some kind of alternative refrigerant. Was this truck originally R-12?

You seem to have bad luck with air conditioning.

Post by **Legacy777** » Fri Oct 29, 2004 3:27 am

To my knowledge it was 134a from the start.

I can try letting some charge out and see if the pressures come down.

I was going to look in the chiltons book on what the pressures should be and it said...only trained professionals should service ac equipment and that it may be illegal for you to mess with......fuck that.

yeah I have horrible luck with a/c systems.

vrg3 · Post by **vrg3** » Fri Oct 29, 2004 3:47 am

You have the Haynes guide to automotive refrigeration, don't you? What does it say?

Refrigerant is pretty cheap... you might just try evacuating and recharging.

Post by **Legacy777** » Fri Oct 29, 2004 2:49 pm

I didn't look at the capacities, just a general guide to what the pressures should be in relation to evap temp and ambient temp.

I really need to buy a vacuum pump so I can just do this damn work myself. I really don't feel like messing with trying to get a custom vacuum pump tweaked and setup......I don't know.

vrg3 · Post by **vrg3** » Fri Oct 29, 2004 3:23 pm

It's not hard to set it up though... I didn't even bother sweating fittings on or flaring the tubing or whatever; I just stuck hose on and used hose clamps. It literally took me like 5 minutes to build my vacuum pump, having already sourced the parts necessary.

Making the connection for the manifold gauges is a little weird... If I remember right, I think I ended up using something like one of each of these:

http://www.fittingsandadapters.com/malsaehosbar.html
http://www.ackits.com/merchant2/merchan ... Code=82634

Post by **Legacy777** » Fri Oct 29, 2004 4:54 pm

I'll have to find the compressors/pumps...... call it whatever, but in my past experience finding stuff for the do-it-yourselfers in Houston is a pain in the ass.

Stuff that I could find up in the north east I can't find down here. Examples: good machine shop that would do some custom stuff for small projects, custom paint mixing and putting it into aerosol cans......etc.

vrg3 · Post by **vrg3** » Fri Oct 29, 2004 5:11 pm

Yeah, I know what you're talking about. I see the difference whenever I go back to the DC area. Stuff that I can easily find up here in Ithaca is impossible down there.

Maybe you could look on eBay. Or just buy used dorm-size fridges or air conditioners at yard sales or something.

Heck, I have a surplus industrialish refrigeration compressor motor I'll send you for the cost of shipping... it's 3-phase so I'm not sure what to do with it, but if you can figure out how to make it run, it's yours.

Post by **Legacy777** » Fri Oct 29, 2004 5:40 pm

Nah I'll pass, I don't feel like electricuting myself

I know enough about electrical stuff to get me by......but haven't dabbled too much with the changing phases...blah blah.

I suppose if I'm really serious about this, I'll start calling around and see what I can find.

vrg3 · Post by **vrg3** » Fri Oct 29, 2004 6:08 pm

Hehehe... Yeah. I'd say cheap used fridges are probably your best source.

"Just be sure to properly evacuate the refrigerant from them."

Post by **Legacy777** » Fri Oct 29, 2004 6:56 pm

I always properly evacuate all refrigerant systems

mikec · Post by **mikec** » Fri Oct 29, 2004 8:18 pm

professor · Post by **professor** » Fri Oct 29, 2004 9:20 pm

your compressor has a high pressure cut-out switch (which operates on the low pressure line), so it could easily be cycling due to high pressure. I'm not sure what the high pressure cut-out is on that system but it is often right around 45 psi.

generally A/C works better with slightly "low" charge rather than slightly high, with high you end up with liquid chasing around taking up heat exchanger space.

I don't know if it is accessible but it would be interesting to put a meter on the high pressure switch and see.

or just take a chance and let some out, you can always replace it for a few bucks.

before doing so make sure your air flow through the condenser is adequate, a slow fan, loose or busted fan shroud, or debris blocking the fins will add up to high pressures and cause cycling.

Post by **Legacy777** » Sat Oct 30, 2004 12:18 am

I'll double check the fan/shroud area, but I'm pretty sure it's clear and fan is working fine.

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OT: Nissan AC

OT: Nissan AC