p.monro Posted November 19, 2003 Share Posted November 19, 2003 My air conditioning does not work. The compressor will not run when the AC switch is pressed and the fan running. I have traced the problem to the pressure switch which is latched open. I had this problem once before and it came right by itself but it seems to be stuck this time. Any one know of a quick fix. If I bridge the contact (to force the compressor on) will it clear it? Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted November 19, 2003 Share Posted November 19, 2003 get a new pressure switch. I believe you can replace it without depressurizing the system. I'm not 100% sure about that.....but it's in the receiver/dryer. I suppose you could bridge the switch, but I'd want to make sure my pressures are good first.....also you can cause some bad issues if your pressures rise too high and the switch isn't hooked up. Quote Link to comment Share on other sites More sharing options...
p.monro Posted November 20, 2003 Author Share Posted November 20, 2003 Hi Josh Thanks for your reply. Yes replacing the switch would be good. I have had the connector off and checked the switch continuity and it is definitely open when it should be closed to pull in the compressor clutch. I was hoping that if I kicked the compressor over it may free the switch up. I am surprised about your suggestion that it may be possible to replace it without depressurising. Have you any more info on this aspect. Thanks Peter Quote Link to comment Share on other sites More sharing options...
RedLance Posted November 20, 2003 Share Posted November 20, 2003 Having worked on the AC systems on my Crown Vic, as well as my Subaru XT, I know a little bit about this. Possibly what has happened, is that you lost enough refrigerant, to cause this switch to not close. This is to protect the compressor, because if the compressor runs with not enough refrigerant, it also doesn’t get enough oil. Usually, the O-rings in the connections get hard, and no longer seal. So check your pressures, or have the system evacuated at a shop, then you can replace the O-rings your self, and have the shop recharge it. If the switch is indeed bad, I'm pretty sure you can just unscrew it and screw on the new one. They screw onto a shrader valve, which is the same valve that tire stems have in them. So...if the car is more then 3-4 years old, I would suspect bad O-rings, and if it were me, I'd replace them. First step is to check your pressures, either by buying an AC pressure tester (ie manifold gauges) or take it to the shop and have them check it. If the pressure is ok, then swap the switch...if the pressure is low, they can probably just top it off, and you'll be good for a couple more years... Hope that helps more then confuses... RedLance Quote Link to comment Share on other sites More sharing options...
p.monro Posted November 20, 2003 Author Share Posted November 20, 2003 Thanks Redlance you have it just right. I was shopping round for a pressure switch and got on to an AC workshop and they told me that the switch was for low refrigerant pressure, from leaking. The same thing happened last year at this time but it came right and I used the AC all last summer so I guess the refrigerant has slowly leaked out. I was interested to hear about the O rings. That piece of information will be of use when I take it into the AC workshop. The system still has the original refrigerant. R16 isn't it. Will they top that up or replace it with the latest version. Regards Peter Quote Link to comment Share on other sites More sharing options...
RedLance Posted November 20, 2003 Share Posted November 20, 2003 What year is the car? If it's older then 1994(I think) it should have R12, which has since been outlawed, and is no longer made. If it's newer then that, it should have R134A. They can top off an R134A system, but not an R12 system. If it's an R12 system, DO NOT let them talk you into using a "drop in" replacement. These are bad, and some are even made with propane...not something I want under my hood. If it IS an R12 system, it's not hard to switch over to R134A, you have to make sure you get all the old oil out, and change the rubber lines over to barrier type. Then, get the new O-rings, reassemble the system, and charge with R134A, up to the right pressure, and you should be fine. RedLance Quote Link to comment Share on other sites More sharing options...
p.monro Posted November 20, 2003 Author Share Posted November 20, 2003 Hi RedLance It is 1993 model and will have the R12 for sure. I know its history from new and it has had nothing done to the AC. Ok I will be aware about a Drop in unit Thanks for telling me about the hoses and the oil. So far I reckon it sounds like about $100 for hoses, $20 for oil and say 2 hours $150 coming to say $300. I suppose there is a shaft seal is that likely to need replacing? Thanks Peter Quote Link to comment Share on other sites More sharing options...
RedLance Posted November 20, 2003 Share Posted November 20, 2003 The shaft seal could very possibly need replacing too. A good way to tell, is to look at the underside of the hood. If there is an oil spot that that matches up to where the belt runs, then it's likely that your shaft seal is leaking too...if there's no oil spot, then it's probably okay. Although, since you will have the system empty anyway, you might as well replace it. RedLance Quote Link to comment Share on other sites More sharing options...
p.monro Posted November 25, 2003 Author Share Posted November 25, 2003 Just got an estimate from the AC specialist for $784 to fix. This is more than air conditioning is worth to me so I will think about doing it myself. The estimate was for labour $220, oil and O rings $18.5, Evacuate and charge to 134A $100, Denso drier $79, Shaft seal TV12C/14C Carbon $73.48, Gasket set ND TV12/TV14/C $66.12,TX valve Block n/Denso R12 $107.32, Retrofit adaptors $15.95 and with $87.13 tax this comes to $784. The DENSO Tx valve aparantley leak at the thread. Can this be sealed somehow without having to buy a new one? What prices do you guys pay for this stuff? Regards Peter Quote Link to comment Share on other sites More sharing options...
RedLance Posted January 11, 2004 Share Posted January 11, 2004 I think I spent about $7 for O-rings, and got my oil at Wal-Mart for like $4. I have my own evecuation system, so I've no idea if $100 is right for that. My drier only cost me $38, I didn't do my shaft seal, my O-ring set came with 2 O-rings that go into the weird fittings where the hoses connect to the compressor. However, this is all pertaining to my 86 XT, which probably has a different compressor. I got retro fit adaptors at Wal-Mart for like $3 RedLance Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 11, 2004 Share Posted January 11, 2004 where'd you get your o-ring kit? Was it a generic one, or specific to your ac system? I need to replace some of the seals on mine, and on the used compressor I put in the shaft seal is leaking......so I may have to swap compressors again. Quote Link to comment Share on other sites More sharing options...
99obw Posted January 11, 2004 Share Posted January 11, 2004 http://www.thetoolwarehouse.net has some o-ring kits. http://www.acsource.com has some too. I bought a $9.99 o-ring kit from Harbor Freight, but I certainly won't be using any of those on an A/C system. I can't decide if I should buy the specific ones for the vehicles and just change them all, or buy an assorment that would cover both vehicles. I am preparing to do flush, oil, replace receiver/dryer, vacuum, and charge on both of our cars, so this is some good reading. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 12, 2004 Share Posted January 12, 2004 I've got the same o-ring kit, but I didn't know if there was a specific one for the a/c system. Quote Link to comment Share on other sites More sharing options...
RedLance Posted January 12, 2004 Share Posted January 12, 2004 I went to a shop here in Lincoln, that does lots of work on older A/C systems. The guy there was able to match my old o-rings up with new ones. RedLance Quote Link to comment Share on other sites More sharing options...
99obw Posted January 12, 2004 Share Posted January 12, 2004 The Harbor Freight o-rings are nitrile, while the A/C ones seem to be green HNBR, whatever that is. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 12, 2004 Share Posted January 12, 2004 Cool, thanks redlance.....may have to try that if I open the system up again. Quote Link to comment Share on other sites More sharing options...
p.monro Posted January 14, 2004 Author Share Posted January 14, 2004 Why change the receiver / drier. My view is that if it is vacuumed at 50 microns for say 1/2 hour then there will be no water left. There was an earlier posting by someone who had done that. My problem is the compressor. You can get them in the USA for $200 os less. Here in NZ they are about US$500. I bet I can get shipping for less than us$300. As for the refrigerant and valve I am going to try to buy a part used cylinder form a AC tech. The small cans here are about $US24 each instead of the price you guys pay arround $5 I believe How are you going to get on with vacuuming again Josh or have you got a pump now? Regards Quote Link to comment Share on other sites More sharing options...
99obw Posted January 14, 2004 Share Posted January 14, 2004 If the dessicant is saturated with water then it won't provide any resistance to moisture in the newly filled system. I am guessing that the vacuum can't boil the water out of the dessicant. The receiver/dryer also has an internal filter on many systems. The old R12 oil also collects in the receiver/dryer. I picked up a used compressor on ebay for $105 for the outback. It was in really nice shape, from an '01 forester. A good ac vacuum pump can be had here for around $200. I have seen some used ones go on ebay for around $100. I am trying to talk my stepdad out of 1 of his 6 spare vacuum pumps. Quote Link to comment Share on other sites More sharing options...
p.monro Posted January 14, 2004 Author Share Posted January 14, 2004 I guess how the receiver drier removes moisture is the question. If it is a chemical reaction then I guess it will not be removed by vacuum. However I understand others have done it with no problem. At high vacuum I guess any old oil will be removed. I have had some experience with vacuuming oil filled equipment and in some systems the oil will boil at 20in Hg. Now I can not say what the boiling temperature is for R12 oil at high vacuum but my guess is that it will all boil off before the high vaccum can be achieved so (I believe) it will pull it out of the receiver. So my belief is that as long as it is vacuumed with a good pump for say 1/2 hour it should be OK. It would be a good idea to fit a vacuum gauge to check that the vacuum goes to 50 microns to confirm this belief. I like your idea of how to get a vacuum pump. If my grandad had not died 60 years ago I would take a look in his workshop but I doubt he would have 6 spare pumps. Ha. Regards Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 14, 2004 Share Posted January 14, 2004 It's standard procedure to replace the receiver/dryer. They can get contaminated over time as well. if you change refrigerants....then you defintely want to change it. If I swap things again, I'll have to get it vacuumed out. I have a buddy at a shop, so he really doesn't charge me much to do it. I suppose I could get a pump, but by the time I get gauges & a pump.....I could have let him do it several times. Quote Link to comment Share on other sites More sharing options...
99obw Posted January 14, 2004 Share Posted January 14, 2004 http://autoacrepairs.com/134aConversion.htm Quote Link to comment Share on other sites More sharing options...
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