95 a/c pressure switch

new to this forum, i found my sister a nice 95 trans sport (and a job to help pay me back) with 115k on the 3.1, every thing works good except the a/c and a leak in the power steering hose. I'm taking it to my mechanic to have the hose changed, mainly because i don't want the mess in my driveway, and a general inspection with emphasis on the intake manifold gasket. he has 4 vehicles with the 3.1 himself and will do the intake maniold for $250 plus parts, maybe i should just go ahead and get it done now, but he won't touch the a/c systems.

She's bringing it over tomorrow and I want to try recharging the a/c myself, does anyone know where the pressure switch and low pressure valve are located? hope they're not a pain to get to like in my grand prix.

Also, while i have a professional mechanic and the vehicle up on a lift, are there any problems specific to this vehicle we should look for?

Thanks in advance guys, eric

where the pressure switch and low pressure valve are located?
FOr a quick check, I already have the diagrams available right here for the '93 3.8, www.avigex.ca/xport/accompressorcontrol.jpg
www.avigex.ca/xport/acpressureswitch.jpg
THe switches and valve are near the accumulator, passenger side of radiator.
THe only difference for the 3.1 electrical are the fuse arrangement (uses only the 15A fuse in fuse block) and an additional feed to the computer from a splice near connector C100. The 3.1 used a diffferent compressor (variable volume instead of on-off control) in '93.....for '95, I cannot tell if they kept the same configuration..
Better check for leaks before filling up with R134...use first bottle with dye maybe.

SInce the 3.1 has a well known history of head gasket failure, I'd run it for a while before changing the intake manifold gasket....jsut in case it would require a more severe job and paying only once would be better than twice.....if it starts overheating, 9.5 out of 10 chances it is a head gasket......just recently my brother in law came with his 3.1 buick overheating..asking for advice...instantly hinted on the head gasket: nobody likes that, he had it checked....and statistics could not be beaten again......
Other common problems are the front wheel bearings, tie rod ends, lower ball joints: they fail more rapidly than the average car...but these are changed easily and best hint is "clunk-clunk" noises when you accelerate from a stop or braking or tight turning at low speed. Worn out wheel bearing will induce a persistent humming sound in straight line changing in intensity as you turn on one side.
....I understand your "interests" include good humour :)....

Thanks for the diagrams LMP, exactly what i needed. I've never had much success with the freon dyes, don't you need an infrared lamp, black light or something like that to dectect slow leaks with the dye? I've always just recharged and if it takes more than 24oz and doesn't come up to pressure and down to temp, i take it to my a/c guy who uses an electronic sniffer to find leaks.

new to this forum, i found my sister a nice 95 trans sport (and a job to help pay me back) with 115k on the 3.1, every thing works good except the a/c and a leak in the power steering hose. I'm taking it to my mechanic to have the hose changed, mainly because i don't want the mess in my driveway, and a general inspection with emphasis on the intake manifold gasket. he has 4 vehicles with the 3.1 himself and will do the intake maniold for $250 plus parts, maybe i should just go ahead and get it done now, but he won't touch the a/c systems.

She's bringing it over tomorrow and I want to try recharging the a/c myself, does anyone know where the pressure switch and low pressure valve are located? hope they're not a pain to get to like in my grand prix.

Also, while i have a professional mechanic and the vehicle up on a lift, are there any problems specific to this vehicle we should look for?

Thanks in advance guys, eric


Just a word of caution use the proper low and high side gauges and proper freon.
Not on of these.
Good Luck MT

Wal Mart DEATH KITS

You cannot properly and safely recharge an air condition system with them.

The one side stop and go gauge does not tell you what your system is doing or is over charged or undercharged.
A overcharged or malfunction air condition system can reach over 500 lbs of pressure.
Enough to blow up that can or system and freeze you at first and the burn you or blind you and if any propane /butane in there blow and light you up.

The stop leak crap and who knows what kind of oil in the kits there will stop your system for sure.
Just like pouring super glue in it.
And some kits even contain freon with a butane mixer.
Good for a big blast.

If you are going to do it do it right and safe.
Here is what you need to start with.
http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=66773

In the older days you could just throw in a can and go.
But over the years just adding freon is getting harder to do.
Newer systems have to have the correct amount of freon down to the ounces.
Most will need pumped down and vacuumed down and the right and amount of oil and a set amount freon charge installed to get the air to cool right and the system to last.
If an air condition is low there is usually a leak that needs fixed and also a lose of lubricating oil from system.
Also air and moisture enters a low system
If you are going to try to do it get the proper type air condition gauge set with the low and high side gauges.
Hook up the gauges and get a reading with compressor running at idle and at 2000 rpm on the high and low side.
Post back pressure reading and we can help you.
MT