i tried the diagnostic codes, that's pretty cool but not any help. everything seems normal.
i jumped the low pressure switch with a paperclip and the compressor kicked in but was still blowing hot... i added some more freon, and now it blows cold, but is leaking from the back of the compressor where the two hoses bolt in... is this just a o-ring problem?? please don't tell me i need a new compressor... they usually leak out the front when they go bad don't they??


how do you replace the low pressure switch (if it turns out to be bad)?? do i just cut the old one off and splice in a new one?

 

The leak is from an O ring. If you do it yourself just unbolt the hose from the back of the comp. and stand back and be prepared for a mess. There are two O rings that you need to change. When you get it back together you need to take it to a shop and have the system evacuated to get the air out that got in when you open the system up. If you don't the system will not take in all the freon it needs, trust me been there done that already. Don't forget that you might have to add a little oil to the system too. good luck. I hate A/C probs.

 

Yes, the manifold connection is a couple O rings seals.
I'll guess you are talking about the 90 (you said freon).
Do yourself a favor,... DON'T just open up the system. The EPA loves to find guy's that do this. That is a shmuck approach. (Sorry hz900)
If you need to, bring it to shop and have them suck out the R12. You will need it when you repressurize they system. A shop will generally do this for very little $, if not free.
It's your choice,... it is a little bit of ozone and $50 worth of R12 that you will waste.

 

"shmuck"? no offense taken I just assummed that if he was doing the job himself it was r134 and not r12. If it is r12 I have to agree with ZylaRace and have the system evacuated by a shop, muuuuuuuch cheaper that way considering the cost of r-12.

 

Don't just unbolt the hose and don't attempt this with the motor hot as system pressure will be much higher. If you're going to discharge the system yourself (assuming you using R134 and not R12), place one end of a charging hose in a coke bottle or a coffee can with a slit cut in the plastic lid. Then attach the hose to the low side fitting on the Accumulator. This will discharge the system and allow you to collect any oil that comes out with the charge. When nothing more is coming out of the low side, move the hose to the high side fitting and discharge any gas remaining on the high side. When done, slowly remove the bolt holding the compressor hose assembly as there might be a tad left. Do not completely remove the bolt until all system pressure is gone. Take whatever seals that come out with you to your supplier as some Nippondenso Compressors use sealing washers and some use o-rings. They are not interchangeable and you need to match them up. Measure any oil that you collected and add that amount back to the system before you pull a vacuum and recharge. The low pressure switch is mounted on a schrader valve and unscrews. Unscrew it rapidly if the system is charged. If you've converted to R134, you want to turn the adjustment screw (between the terminals) about one turn counterclockwise. This will reduce it's cutout pressure from 24 - 25 psi to 20 -21 psi, which is what you need with R134.

 

i have already done the 134 conversion, and the leak was significant enough that there is no pressure left in the system... will the oil spill all over when i take the compressor hoses off??

other than filling the system up over and over, and discovering new leaks each time (hopefully there are none) ... is there some better, more systematic way to do this?? (just in case) i don't have a sniffer or the UV equipment (I didn't wanna spring for the AutoZone kit)

i found the low pressure switch, but (this is probably a dumb question) is this adjustment screw on the switch itself or in the rubber plug that goes on the switch??


thanks for all of your help!!

 

Any oil that was lost went with the charge. Probably less than an ounce, but it wouldn't hurt to add an ounce back before you recharge. Suggest you put it in the compressor hose (outlet side from the evaporator to inlet/suction side of the compressor). This will ensure that some oil gets to the compressor when it first starts. Evacuating or pulling a vacuum (at least 29 inches at sea level) not only gets the moisture out but will also give you some idea as to whether or not it's going to leak. A decent evacuation takes at least an hour and a tight system will hold it overnight. It isn't foolproof since only atmospheric pressure can get back into a vacuumed system and operating pressures are much higher. If it won't hold a vacuum, best to have it leaked check at a shop, but the most common areas for a leak are the evaporator core and the compressor shaft seal. Also, if you didn't replace the old o-rings to R134 compatible ones, do it now or they may begin to leak also. The adjustment screw is on the switch between the terminals. Some aftermarket switches don't have it and if yours doesn't, best to get one from GM.