What is the correct A/C refrigerant pressure for '04 Scion xB?
May 31, 2014 10:49 AM   Subscribe

What is the proper air conditioning refrigerant pressure for a 2004 Scion xB? Should the pressure reading be made at a specific RPM? My A/C has been slowly loosing cooling over the last couple of years, now it really only cools well when traveling above 35~ mph, not so well at all in stop-and-go situations. Does it sound like I am on the right track to recharge the system? Works pretty well at steady-state speeds...
posted by Exchequer to Travel & Transportation (6 answers total)
download the shop manual here and have a look.

The performance you're describing sounds like it needs a recharge though, yes. In my experience AC recharging is less of a measure and definitively answer thing and more of a perceptive thing. Some cars have AC systems that work great seemingly forever even as they age and leak and stuff even when they aren't at optimal pressure(subarus especially, from what i've seen), others... not so much.
posted by emptythought at 12:40 PM on May 31, 2014

It's clearly down on pressure from your description - take it in and get it recharged. I don't know if you can get those aerosol refill things but it's more environmentally responsible to get it fixed - a slow leak is likely just a cheap seal, which will prevent a need for recharge later on.
posted by Brockles at 2:37 PM on May 31, 2014

Over a couple *years*?!? Yeah, get a recharge. Shop rate for evacuate and recharge is about an hour, plus the refrigerant, which isn't much. Have them put some dye in with the pump oil when they're recharging, and if it fails more quickly, they can find the leak.

As to directly answer your question, the correct pressures (low and high sides) depend on the ambient temperature and humidity when testing.
posted by notsnot at 2:57 PM on May 31, 2014

Response by poster: Ambient temp 95 - 100 f and relative humidity 5-15%.
posted by Exchequer at 3:57 PM on May 31, 2014

Response by poster: @emptythought,

"...the publicly available information about maintaining your Scion is no longer available on this site..."

"Admin, ScionLife.org"

posted by Exchequer at 4:01 PM on May 31, 2014

First thing you might want to try is replacing the cabin filter, which can hinder the performance of your A/C system if it's gunked up enough. That probably won't solve the problem, but it could help. If you can get to the evaporator, take a look at that too, and see how dirty it is.

Automotive air conditioning repairs are complicated and potentially dangerous enough that, unless you have some experience with repairing these kinds of things, it's best to have a trained technician look everything over and, if necessary, recharge the system. If you want to go ahead with this on your own, you should, at the very least, buy the Scion shop manual so that you're not just flying by the seat of your pants. Seriously, you can incur horrendous injuries, including freezing your face off, from trying to do A/C repairs without the requisite skill and experience. Please have a repair shop do this if you're not 100% sure of what you're doing.

Repair shops will usually diagnose your system for free or for a modest fee. Refrigerant really shouldn't be leaking out, no matter how slowly, which means that you may have an underlying issue that needs to be addressed. It's pointless and a waste of money to try to recharge the system if the real issue is, say, a marginal compressor. Take it in to a garage you trust and have them go over the A/C system with a fine-toothed comb.
posted by Leatherstocking at 9:30 AM on June 1, 2014

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