It's been over 100* everyday for the past 3 weeks and sittibg in traffic for an hour dam near causes me to pass out, I've got to get my AC working......PLEASE HELP!!!

Ok, I bought my 1998 Auto used and the AC has never worked. I already fixed the HVAC display by resoldering the capacitors as shown in the how-to, so the controls and display are working. When I push the AC on/off button, the light just blinks and then shuts off. I tried adding freon to get the pressure up thinking the compressor wouldn't engage due to low pressure. It wouldn't come on and the pressure quickly dropped back to almost nothing. Obviously I have a large leak somewhere in the system. Are there some common areas I should check first? What order should I check the A/C system components in and how do i check them? Should i try adding the ultraviolet dye? I'm very capable of performing all the maintenance and repairs/upgrades on my carm however the AC system is somewhat of mystery to me. I'd prefer to do as much of the work as possible on my own, please keep this in mind when providing advice. Thanks in advance.

 

A leak that large should leave an oil residue.But 134a is hard to detect without a good leak detector.Take it to a pro and at least let them point the leak out to you,then if you can, do it yourself.

 

Look for oily residue around the compressor clutch and pulley.

Leaking shaft seals are very common on these compressors.

 

I'll do that here in a bit. It has been a couple months since i tried to charge the system and who knows how long since the system worked and the compressor run, so will freon even be able to circulate thru the compressor to leak at those seals? And let's say it does have an oily residue, can those seals be replaced individually or do I have to get a whole new compressor? Sorry for all the questions, but I'm learning as this is all new to me and I'm trying to kind of run thru a process of elimination to fix my AC. Thanks.

 

I havent heard of anyone replacing a/c compressor seal in years,even under warranty they replace the unit.

 

If you have a large leak, just charging it up isn't a good idea. You will need to fix the leak and then replace the accumulator, the orifice tube the oil that is missing and then evacuate the system with a vacuum to achieve 29 inches of Mercury and then recharge with the correct R-134 charge.

If you charge it back up and use it, the moisture in the system will cause the system to eat it self form the inside out and you will develop tiny pin holes in the aluminum piping.

 

Hi, Searching for a leak is not the hardest thing to do, but it can be tricky. If you put refrigerant in the system, put some dye in with it. Put in a few pounds of ref, with a few ounces of dye, even if the comp doesn't run the ref and dye will get in there and if the leak is large come out quickly.(My guess would be that your leak is right at the comp judging by how fast you say the pressures are dropping to 0. Then use a black light to find it. If the leak is not huge the comp should at least cycle on and off if you put enough in fast enough. Some of the most common places they leak is the seals at the comp inlet and outlet, the center of the comp at the seam, the comp clutch area, any joints and connections, the evaporator coil, and the condenser. You will be able to see most of those places except the evaporator which is inside the plenum. If the evaporator is leaking that badly you should hear it as you are putting in the ref, if you get the comp to run for a little while you can check the condensation that falls on the ground below the car with a black light for the dye that will be in it, substantiating the evaporator leak.
Once the leak is found and fixed see below for charging info.
++++++++++++++++++++++++++++++++++
1, It is best to charge and check levels on the vette at 2000 rpm's, it can be done at 1000, or 1500 accurately, but you have to compensate for the lower rpms, with higher pressures. As the rpm's increase the low side will go lower, and the high side higher.
2, At 2000 rpm's with an 80% relative humidity, and ambient temp at 80 degrees, the low side should be 34psig, and the high side right around 250psig, this should yield at least 50 degrees or lower at the center duct with a thermometer.
If the temp is 90 degrees and the humidity is 80% the low side is 39psig, and the high around 310psig, this should yield 67 or lower at the center duct.
At 100 degrees and 60% humidity, low is 38psig, and high is 350psig.Humidity levels do make slight differences in the optimum read levels, as do temps. But if you get close to those numbers you will have an optimum system.
3, The proper way to make sure you have optimum levels is to evacuate the system, as you don't really know who worked on it before you, and might have let air or moisture, or even the wrong refrigerant in it. Then pull a vacumn of at least 29inches, for a few hours to dry it out, then recharge it being sure to add some proper oil. If it hasn't been disassembled, usually about 4 to 6 ounces of oil will be enough to protect the system. If you suspect a leak, which you should, because refrigerant doesn't wear out it leaks out, a bit of dye added will help you find it.
Good Luck

 

The o-ring seals at the accumulator, evaporator, condenser, and orifice tube connections are easily replaced.

The compressor shaft seal replacement is difficult, and it requires some special tools for removing and replacing the clutch and seal. A new or rebuilt compressor is probably your best option there.

 

thats what i was looking for "bestvettever", thank you! and thank you to everyone who posted. Now I have a starting point to get this thing workin again. I'll start chasin down the leaks and get a few prices on compressors just in case. How do i evacuate the sytem? Also, any idea on what it would cost to have the system vacuum/refilled from zero?

 

Hi Boost, To evacuate the system you need to let all the refrigerant out,(it is illegal to vent refrigerant to the atmosphere), into a tank, (you can use an old ref tank and take it to an AC shop for recycling), then you need to hook up a vacumn pump to the hi and low side and pull the system down to a 29" vacumn, and allow it to continue pumping down for a few hours to dry it out, even overnight would be a good thing to do in a system that has been open. When you turn off the vacumn pump, let it sit for a little bit to see if it holds the vacumn, if it does it should hold the pressure of the recharge, if it doesn't you need to search further for the leak/s. Vacumn pumps are not cheap, but sometimes can be rented, another option is to use an old electric compressor, ie: an old refrigerator, freezer, ac, dehumidifier motor. fabricate an end that can connect to
the inlet,(low suction side port,) connect a line to the center hose of your guages from the suction line of the old compressor, turn it on and let it run till the job is done, the lines from the guages will be connected to the high and low side of the car ac system and the valves open, when the job is done, close the valves to hold the vacumn, disconnect the old pump, and connect your refrigerant source to the center hose of the guages. Purge air from the center line, Let ref into the car ac system to get a positive pressure untill no more will enter, then turn on the car ac system, set therm to max cold, 65 in the vette, leave the windows open, put a thermometer in the center vent, and charge to proper levels using the can or tank in an upright position to protect the comp valves from slugging liquid. It sometimes helps to put the can/tank of 134 in some warm water, but do not allow water near the outlet of the can/ tank.
Of course before you waste time on the evac and refill, make sure the leaks have been fixed and if the system was open you should replace the accumulator drier.
Some other good ways to find or eliminate possible leak sites is, disconnect the lines going to the evaporator and hook a line from a tank of nitrogen or compressed air to one line, close off the other and pump about 100 lbs of pressure into the evaporator, (you can do the same thing with the condenser, and the compressor), if the pressure drops there is a leak in that component. You are basically isolating that component and pressure testing it. Normally you would not introduce anything other that refrigerant into the system, but since you are going to open it up, fix the leak, and evac and refill it,it is ok to do in that circumstance. As an alternative to using guage pressures to charge the system you can put a weighted charge into an empty system, factory fills were 1.5 lbs but they changed it to combat evaporator freezes under certain circumstances, to 1.75 lbs so that is 28 ounces. I think cans of ref come in 12 ounce cans so that equals 2 1/3 cans, and be sure to use a can with added oil to replace the oil lost in the leaking. If you have a 15 or 30 lb tank of ref, put it on a digital scale and watch the weight as you do the refill, when you lose 28 ounces from the tank, your full.
As for what a shop charges to evac and refill, it varies a lot, but you should be able to find someone to do it for less than 100.00
Good Luck

 

Thank you so much. This is all great info. I got called in to work so I havnt had an oppurtunity to start chasing down the leak yet, but i'm definately feeling a lot more confident about getting this repaired and working properly in no time.