Matt Posted June 23, 2005 Report Share Posted June 23, 2005 Hey Guys. Thanks to those last night who offered me advice on the Low pressure switch. This started when my Mom said her AC will not go on and there is a message on the dash that says the Compressor is off. I pulled codes for low freon condition. I asked a few questions last night that prompted me to go farther at work today. I got a hold of the manifold and guages to do this right. There are R132 type fittings on the manifold set up. My Moms car has the fitting that is used for R132. It's like a push on shop air fitting. That should be R132. I will look better again for that little sticker that tells what is in the system. My car has R12 and the valve is like a bike tire tube shrader valve fitting. So this weekend I will check pressure. I was told here last night that at 90 Deg outside I should see around 30 to 40 psi on the low side. I will double check the post. I have a chart that should show the hi side reading. I need to get better info on that stuff though. The old chart I found at work is not very good and confusing. I want to know Low and Hi side pressures at a range of different temps and for R12 and R132.. I will feel more comfortable that way. If any body has a link to those charts or info on those pressures please let me know. Then if there is pressure in the system I will jump the low side pressure switch, if the compressor comes on I will replace that 22 dollar switch. I hope I got this figured out right. My Mom remembers the AC coming on not to long ago when useing the defrosters, so hopefully just the switch went bad. Got to go, my girl has a honey do project for me before we turn in tonight. I hope to be rewarded afterwards. Be back in the AM from work. Have a good night all.... Link to comment Share on other sites More sharing options...
KHE Posted June 23, 2005 Report Share Posted June 23, 2005 Hey Guys. Thanks to those last night who offered me advice on the Low pressure switch. This started when my Mom said her AC will not go on and there is a message on the dash that says the Compressor is off. I pulled codes for low freon condition. I asked a few questions last night that prompted me to go farther at work today. I got a hold of the manifold and guages to do this right. There are R132 type fittings on the manifold set up. My Moms car has the fitting that is used for R132. It's like a push on shop air fitting. That should be R132. I will look better again for that little sticker that tells what is in the system. My car has R12 and the valve is like a bike tire tube shrader valve fitting. So this weekend I will check pressure. I was told here last night that at 90 Deg outside I should see around 30 to 40 psi on the low side. I will double check the post. I have a chart that should show the hi side reading. I need to get better info on that stuff though. The old chart I found at work is not very good and confusing. I want to know Low and Hi side pressures at a range of different temps and for R12 and R132.. I will feel more comfortable that way. If any body has a link to those charts or info on those pressures please let me know. Then if there is pressure in the system I will jump the low side pressure switch, if the compressor comes on I will replace that 22 dollar switch. I hope I got this figured out right. My Mom remembers the AC coming on not to long ago when useing the defrosters, so hopefully just the switch went bad. Got to go, my girl has a honey do project for me before we turn in tonight. I hope to be rewarded afterwards. Be back in the AM from work. Have a good night all.... If there is a low refrigerant code set, then the system IS low on refrigerant. I wouldn't start replacing parts - use the manifold gages and post back the high and low pressure readings at high idle. My guess is that the system needs a little refrigerant and it will be fine. If the message returns, then you will need to locate and repair the leak. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Matt Posted June 23, 2005 Author Report Share Posted June 23, 2005 Hey Guys. I am happy to say that I just had an AC lesson from one of the guys I work with. I also was given a two page copy of a diagram and description on how an AC system works. It is wonderfull, it made understanding it all very easy. When you have an understand you loose the fear and in return gain confidence. I want to post this two page document, actually it's one page total. It's just on two pages. If everyone could see and read this they will have a good understand too, that would be very nice for anyone who is a bit unsure about all of this. I will see if my friend comes in today, he has a scanner. If he takes off I will wait till tonight to scan it myself and post it.. KHE- thanks very much. I cant wait to work on My Moms car AC now. I would never have thought to try this in the past. I have put in a can or two of R12 in older cars I once had but now would never think of just putting in anything with out doing it the right way. Thanks to this board I have been taught well. Later guys... Link to comment Share on other sites More sharing options...
Matt Posted June 24, 2005 Author Report Share Posted June 24, 2005 Sorry about not having time to scan and post the AC info last night. I will try and get it done tonight, Fiiday. Link to comment Share on other sites More sharing options...
Matt Posted June 24, 2005 Author Report Share Posted June 24, 2005 OK I have everything I need to check my Moms AC in her car. It is a 93 Eldorado with a 4.9L. I have the manifold with hoses and guages and I have the big tank of 134a. I have a chart that shows different freons and PSI according to outside temps. But I'm not positive on the chart. One side shows "Pressure Temperature Chart" with listed freons of R12-R22-R134a-R502 and R410a. Then it tells ya dfferent temps in Farenhight,example= R-134a at 90 deg outside temp should be 105 PSIG. I figure that is Pressure on the HI SIDE... I have no chart showing the LO SIDE except info on the board from posts under Scottys AC job ware I had asked questions and was told that LO SIDE should be between 30 and 40 PSI at 90 Deg outside. I need a few more reference points of different temps in case it's not 90 Out. Now on the other side of this chart It says " Refrigerant Temperature". But the freons listed are R401a-R401b-R402a and R402b. These are not what I'm working with so I will not worry about this side of the chart. I just need to know a bit more to be confident. Scotty do you know what were the settings for your car? Thanks for the help guys. I have till Sunday to learn more about this.. Later Link to comment Share on other sites More sharing options...
Ranger Posted June 24, 2005 Report Share Posted June 24, 2005 Matt, maybe this is what you are looking for. P.S. not my post re: A/C Differences http://autoacrepairs.com/temperature.htm Link to comment Share on other sites More sharing options...
Matt Posted June 24, 2005 Author Report Share Posted June 24, 2005 Thanks lary, there is much info on that site. I made a quick print out and will look over the site good tonight. I picked up something allready." Do not open the service valve on the tank to the hi side with the compressor running". Instead fill from the low side! I guess that will bring up the pressure on the Hi side. Looking at the chart I guess it will. Thanks again.. Later... Link to comment Share on other sites More sharing options...
Scotty Posted June 24, 2005 Report Share Posted June 24, 2005 Matt, I dont know what the setting were, I let a shop evacuate it and recharge it... just doing the mechanical work was enough for me... Mike Link to comment Share on other sites More sharing options...
Matt Posted June 24, 2005 Author Report Share Posted June 24, 2005 Yes you did the hard part of it. I understand at least that way you know what and how it was all done. That is a big pluss now a day with so many shotey places out there... Later Mike. My day is almost done and WOW my shop is hot.... Link to comment Share on other sites More sharing options...
Ranger Posted June 24, 2005 Report Share Posted June 24, 2005 Thanks lary, there is much info on that site. I made a quick print out and will look over the site good tonight. I picked up something allready." Do not open the service valve on the tank to the hi side with the compressor running". Instead fill from the low side! I guess that will bring up the pressure on the Hi side. Looking at the chart I guess it will. Thanks again.. Later... Matt, That is very very important. NEVER EVER open the high side (red) valve while it is hooked up to the system and it is running. You'll likely turn the 12 oz. can you are holding into a grenade (with the pin and spoon removed). Not sure if the large tanks can take the pressure or not but then that grenade would become a bomb. The only time that I can see when the high side (red) valve is opened is for vacuuming down the system. It is mentioned in there. Yes, always service from the low side. That will bring both low and high up as freon is added. I went through that site completely yesterday and you are right. There is a LOT of good information in there. I learned a few things. Link to comment Share on other sites More sharing options...
navion Posted June 24, 2005 Report Share Posted June 24, 2005 Matt, Just to be safe, recharge your Mom's system with the can or cylinder upright. This will allow only gaseous refrigerant into the system. If you have the cylinder or can upside down, it will allow liquid refrigerant into the car's system. Some cars can take liquid on the low side and some can't. If liquid refrigerant reaches the compressor, then you WILL have a problem! It will lock up the compressor & most likely damage it. It takes a little longer to charge with gas, but it i$ $afer. Good Luck Britt Britt Link to comment Share on other sites More sharing options...
navion Posted June 24, 2005 Report Share Posted June 24, 2005 Matt, I forgot, if your Mom's Eldo is displaying the low refrigerant warning, you will probably have to disconnect the battery momentarily to clear that message. You will not be able to start the compressor with the low refrigerant message set. Check your manual. Britt Britt Link to comment Share on other sites More sharing options...
KHE Posted June 25, 2005 Report Share Posted June 25, 2005 Matt, Just to be safe, recharge your Mom's system with the can or cylinder upright. This will allow only gaseous refrigerant into the system. If you have the cylinder or can upside down, it will allow liquid refrigerant into the car's system. Some cars can take liquid on the low side and some can't. If liquid refrigerant reaches the compressor, then you WILL have a problem! It will lock up the compressor & most likely damage it. It takes a little longer to charge with gas, but it i$ $afer. Good Luck Britt Most GM Systems have the low pressure port on the accumulator - I always charge as a liquid - you won't damage the compressor as any loiquid refrigerand IMMEDIATELY vaporizes upon entering the accumulator through the low side port so the chance of slugging the compressor is non-existant.... Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Matt Posted June 25, 2005 Author Report Share Posted June 25, 2005 Hey Guys, WOW what a long day. It's nice to be back in the AC of my home. It's still 84 and humid outside. I will be going up in the early AM to work on the car. Yes I will remember to never open the hi side wile car is running and or compressor is running. That is only done to evacuate the system. True I want nothing to go " BOOM"!!! The tank I have is the large one. It felt like maybe 25 LBS bringing it into the outside porch. Yes thats a good point, I will have to get the compressor to spin if the system is low in order to suck freon in. Right now the compressor is not going on. That may be a problem. I guess if I clear the code and hook up to the low side and open the valve slow putting some pressure to the system it may take right off and spin when I start the car. I will have to be carefull and get to the valve quick to make sure it does not over pressure the system. OR If I clear the code and jump the low pressure switch I can get the compressor to spin right off as I start the engine. Then I can go to the valve and open it slow just a little and watch the guage. What ever I do I just have to be carefull. The tank of freon I have is a big tank with lots of pressure behind it. The guy at work told me to stand it upright when doing this and let it feed in gas. He said there is lots of pressure so be carefull and open only a little and watch the guage. He said put in only a little at a time and then let is stablize a bit, watch what it does and go from there. You know my biggest worry is transporting the tank to my folks home. I brought it home today and with my AC on in the car it was nice and cool so I guess it will be ok. I just hope I do not brake down or anything. I would have to put the tank into the woods and not leave it in the car so it does not explode. Well lets see how it goes. This will be interesting.. Link to comment Share on other sites More sharing options...
WarrenJ Posted June 25, 2005 Report Share Posted June 25, 2005 Freon info . . . . Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
Matt Posted June 25, 2005 Author Report Share Posted June 25, 2005 Good Morning all. Thanks Warren, I printed that chart also. I will be leaving soon to go do the job. I will report back later on. It's all ready 80 outside, not looking forward to this trip....... Link to comment Share on other sites More sharing options...
Matt Posted June 25, 2005 Author Report Share Posted June 25, 2005 This is what I found out upon arriving at my Moms. The Eldorado AC actually stoped working a few weeks back and was taken to a mechanic they know to be serviced. The verdict was that there was very little freon in the system but there was some.. The AC was recharged and for some unknown reason it would not work, the compressor would not run. My parents were charged $125.00 any way and told it must be something else that has gone bad. DAaaa!!! They were told to set up another day to come in for more repairs and to spend more money. --------- So today I went and looked things over, this time in the day light. The first thing I found was the sticker for the freon gas. It was not 134a but R12. My car has R12 and the fittings are completly different then what is on my Moms car. They looked like 134a fittings at night. So now these fittings are different then my R12 fittings and different then what is on the Manifold set for the 134a gas. So what the heck are they? It is a type of push lock, like a shop air fitting and like the 134a fittings on the manifold gauge set,yet the manifold hoses do not lock on, but also there are threads on the inside of this fitting on the cars low side. The high side is the same type just much larger. I need to ident these fittings for future refference. So now I had to figure out what to do next, I was not going to let that stop me. True I wanted to see what kind of pressure was in there but that mechanic said he filled the system. So I went on the theory that the system was charged. OK next; I pulled the wires from the low side sensor/switch and jumped them with a paper clip. Then I disconnected the battery for about 2 min. to reset the PCM. I reconnected the bttery and started the car and turned on the AC. The compressor came on and within a few miniuts the receiver/drier was freezing cold and dripping wet. The AC output in the cockpit was freezing cold. The compressor was not going on and off the way they do when the system is low on freon. NOW-- next I shut her down and thought about something, it was, what if the bone head did not clear the codes before testing the system???? I reconnected the wire to the sensor on the low side and restarted her up and turned on the AC. BINGO, the compressor came on and the AC was cold. Everything seemed to be working fine. The system held pressure so I guess that is ok, after all a leek is a leek and there would have been no freon at all if there was a leek. Could that have been the answer? The codes were not cleared? This was to easy, what am I missing here? I do not know a lot about AC so is it going to stop working again? Is it that My Parents were being set up to be" taken" for more cash? I do not believe everybody is crooked so maybe the mechanic just forgot to clear the codes. I ran the car and shut it down for a wile and ran it again, the AC was working fine. I wish it was cooler out so I could see the compressor go on and off but it is to hot and very humid out so the compressor just stayed on. It was about 91 when I was working on it all. It's 97 now here at home. Yikes... I guess we will have to see if it keeps working. Thanks to those who helped me with charts and experience. My Mom is set now, I hope!! Later Guys.... Link to comment Share on other sites More sharing options...
KHE Posted June 25, 2005 Report Share Posted June 25, 2005 R-134a fittings are the push-lock type - sort of like an air compressor line fitting. R-12 fittings are a standard, threaded fitting. 1993 was the last model year that R-12 was used. R-134a was first used in the 1994 model year for GM products. It sounds like your Mom's car is R-12 and your car has been converted to R-134a??? Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted June 25, 2005 Report Share Posted June 25, 2005 Matt, The internal threads on the R134a fittings are for the caps. Large one is high side (red), smaller one is low side (blue). You need to push kinda hard to get them to seat. Support the line from underneath and snap it on. Link to comment Share on other sites More sharing options...
Matt Posted June 25, 2005 Author Report Share Posted June 25, 2005 Hey Guys. My car has the standard threaded fittings, so I believe it is for R12. My last car had the same fittings and it was R12. That is interesting about my Moms car, you say you have to push very hard to get the hoses from the manifold on? I thought I pushed on them very hard yet they would not snap on. If any thing, because of the fittings on my Moms car it looks like her car was converted to 134a. On the receiver/drier there is a sticker for R12, but that does not mean some one did not convert it over. I have no idea what has been done to that car. The fittings are the tell tale signs. I just could not get the fittings on the manifold hoses to snap on. As far as what happened, I beleve the system was low and the mechanic charged the system up. Then he did not clear the codes in the PCM. He then tried to run it and it would not come on. AT that point he must have been stumped. After I reset the PCM it ran fine. The Low Freon code did not come back and it worked fine. I will have to go to a 134a veichle at work and tri the manifold hoses again, or get one of the guys to show me how to get them on. I will do that on Monday. I would like to check the pressure on my Moms car but it seems that it was charged up. It is working good. I think it was just that the code was not cleared. Time will tell..... Link to comment Share on other sites More sharing options...
KHE Posted June 25, 2005 Report Share Posted June 25, 2005 Hey Guys. My car has the standard threaded fittings, so I believe it is for R12. My last car had the same fittings and it was R12. That is interesting about my Moms car, you say you have to push very hard to get the hoses from the manifold on? I thought I pushed on them very hard yet they would not snap on. If any thing, because of the fittings on my Moms car it looks like her car was converted to 134a. On the receiver/drier there is a sticker for R12, but that does not mean some one did not convert it over. I have no idea what has been done to that car. The fittings are the tell tale signs. I just could not get the fittings on the manifold hoses to snap on. As far as what happened, I beleve the system was low and the mechanic charged the system up. Then he did not clear the codes in the PCM. He then tried to run it and it would not come on. AT that point he must have been stumped. After I reset the PCM it ran fine. The Low Freon code did not come back and it worked fine. I will have to go to a 134a veichle at work and tri the manifold hoses again, or get one of the guys to show me how to get them on. I will do that on Monday. I would like to check the pressure on my Moms car but it seems that it was charged up. It is working good. I think it was just that the code was not cleared. Time will tell..... The "ball" in the R-134a fittings sometimes sticks and can make attaching the hoses tough. They just need some persuasion.... From your description, someone must have converted your mother's car to R-134a but did not apply a retrofit label. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted June 26, 2005 Report Share Posted June 26, 2005 Pull back on the outer ring on the coupler, then snap it on. Just like doing it on shop air. Link to comment Share on other sites More sharing options...
Matt Posted June 26, 2005 Author Report Share Posted June 26, 2005 Thats the funny thing about it, there is no ring to pull back. I cant understand it. It's the wierdest thing. I will have to go outside later and get the manifold and take a pic and post it. Link to comment Share on other sites More sharing options...
Ranger Posted June 26, 2005 Report Share Posted June 26, 2005 Hmm, now you got me. Link to comment Share on other sites More sharing options...
Matt Posted June 26, 2005 Author Report Share Posted June 26, 2005 Hey Lary, sorry for taking so long to post the pic. I found what I did wrong. I did not open the valve to be able to pull back the ring. Take note of my error everyone... So another day goes bye and yet another lesson........ Cheeeessss Link to comment Share on other sites More sharing options...
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