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Car Forum / Volvo Cars / June 2004air conditioning Q - topping off R134a at home?
So the air conditioning of my '93 960, R134a system is working but not all that well. Cool, but not cold air. I thought that one of the home recharge kits would be OK to top off the system. I have been reading and found a lot of generic tips, but not specifically for this car, and do I need to add, "Chilton was of no help"? I got a home recharging kit with a low-side pressure gauge, but have read that the total coolant in the system should be evacuated, weighed, then replaced with the addition of R134a to create the correct total amount. I was thinking that I would run the air conditioning at idle, on high, and put a fast-reacting digital thermometer's sensor in a vent, and while staying in the correct charge zone on the gauge, SLOWLY add R134a while watching the temperature of the air coming out of the vent. First, is the port next to the 'cylinder' (looking like an aluminum propane bottle- is that the accumulator? a guess as the Chilton didn't even have a diagram with the parts named) near the dash the correct low-side port? A cursory inspection revealed this to be the only one I have found so far, but it was late and dark when I looked. The black plastic, screw-on cap on that port says something like "Max 6Nm" on it. I thought Newtom meters was a torque setting and so i am assuming that this is in reference to the torque to be applied to the charging adaptor affixed to teh prot when charging and nothing to do with the level of charge itself. Is that right? Am I heading in the right direction? Is it worth a try? Should I just return the kit and take the car to a shop for recharging? Should I just move to a colder climate? Hey, Rob? What does a home go for where you live? ;-) from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate >So the air conditioning of my '93 960,...snip Can anyone read my original post in this thread? Having probs in othe groups and wondering if anyone say it? THANKS and sorry for replying to my own post. from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate Randy: We can't tell if you should move somewhere else unless we have some idea of where you live now... :-) OK, if you're just getting cool air, when you had cold before, what temperature are you actually getting, and what's the ambient temperature? Generally, with a normally working system, you should see a good 30 degree drop from outside air to inside discharge while at high idle, after running for a few minutes. Freon tends to be a funny thing, especially 134a. Too much can actually cause less cooling than not quite enough. Generally, the kits you can get at the local department or parts store will only let you read the low side pressure, and that's just not enough to know what is really going on. Yes, as you've read, the "right" way is to have the system evacuated and recharged with the correct amount of refrigerant. However, many people have found that if they have low pressure on the low side, along with insufficient cooling, if they add a partial can, everything works fine. Adding a full can, however can really be "too much of a good thing" if it exceeds the capacity of the system because it puts a very high load on the compressor and can cause permanent damage (and I can tell you, compressors are not inexpensive!). The low pressure port is a different size from the high pressure port on R134a systems, so you shouldn't be able to connect to the wrong one, but if you can't identify it from the information you have, perhaps you should get someone to give you a hand. Thanks --Rick > So the air conditioning of my '93 960, R134a system is working but not > all that well. Cool, but not cold air. I thought that one of the home [quoted text clipped - 34 lines] > \__/olvo > 1993 960 Estate >Randy: > >We can't tell if you should move somewhere else unless we have some idea >of where you live now... :-) It's freakin' hot here! Nor Calif. been around 90-95f for the last week or so. Down in the valley it's even hotter! >OK, if you're just getting cool air, when you had cold before, what >temperature are you actually getting, and what's the ambient temperature? >Generally, with a normally working system, you should see a good 30 degree >drop from outside air to inside discharge while at high idle, after >running for a few minutes. I had thought about all that, but had not quantified it at all. I would say that it is not 30 cooler, but I will check that out before I consider adding any 134a. I did get the gauge that measures the low side, and I have identified it correctly as the high side port SEEMS to be on the back of the compressor, by feel, but my head is to big to get down in there to see ;-) >Freon tends to be a funny thing, especially 134a. Too much can actually >cause less cooling than not quite enough. Generally, the kits you can get >at the local department or parts store will only let you read the low side >pressure, and that's just not enough to know what is really going on. Yes, I have been reading about that all over the net. This is what made me think that the combination of the gauge and a digital thermometer with a long probe wire will let me check the gauge as well as the temperature of the air coming out through the vent at the same time. I can add little bits of 134a and see the effect on the temperature of the air coming out. >Yes, as you've read, the "right" way is to have the system evacuated and >recharged with the correct amount of refrigerant. However, many people >have found that if they have low pressure on the low side, along with >insufficient cooling, if they add a partial can, everything works fine. That's what I thought. I wouldn't even think of adding 134 if i didn't have the gauge, but thought that I would ask here first anyway. What with spending over $200 on a rack and pinion last week I thought I would try to save a few dollars right now on this job... I figured that if the gauge and fill kit with a large can of 134a cost $25, it would still be less then going to an AC shop to find out that the level was low or not... >Adding a full can, however can really be "too much of a good thing" if it >exceeds the capacity of the system because it puts a very high load on the >compressor and can cause permanent damage (and I can tell you, compressors >are not inexpensive!). There are Inexpensive parts on a VOLVO!? You got a list? ;-) >The low pressure port is a different size from the high pressure port on >R134a systems, so you shouldn't be able to connect to the wrong one, but >if you can't identify it from the information you have, perhaps you should >get someone to give you a hand. Then I did find the correct port. makes sense that it is up where it is easy to get to like most other service items on this car.. The tranny dipstick is another matter all together! And thanks for the reply. Much appreciated! from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate > There are Inexpensive parts on a VOLVO!? You got a list? ;-) I can start that off:- The little U shaped plastic screw covers on the roof rails. The kit should have instructions on it. I would follow the gauge that should be included, but be careful not to overcharge. The 6 newton-meter is the torque, not a lot really - basically hand tight. The temp may not provide info for over charging. Does the ac cycle on off? If so, add a bit and see if it stops. I use the intermatic kit and have good results on my 850. Jeff > So the air conditioning of my '93 960, R134a system is working but not > all that well. Cool, but not cold air. I thought that one of the home [quoted text clipped - 34 lines] > \__/olvo > 1993 960 Estate >The kit should have instructions on it. I would follow the gauge that >should be included, but be careful not to overcharge. The 6 newton-meter is >the torque, not a lot really - basically hand tight. The temp may not >provide info for over charging. Does the ac cycle on off? If so, add a bit >and see if it stops. I use the intermatic kit and have good results on my >850. I played with it last night. I added some and then stopped as I have decided there are other issues.. maybe. the high pressure pipe got quite cold under the hood where it enters the cars and was dripping from condensation. The air in the car was cold at first then seemed to get warmer. Icing? I am not sure. I also believe that I have a bad vac actuator motor in there as well becasue the cold air only comes out of the two dash vents nearest the doors, and the two center vents in the dash blow warm air. Maybe the heater control valve is also bad? I know the dual acting vac motor at the driver's foot area is bad and needs to be replaced. I was considering doing the cut and hack job to replace it (opening a hole in the air box behind the console to access the flapper), but it seems I also have other issues to deal with. I think I might get the Volvo shop book on the heating air conditioning system and see what that says. I don't mind taking the time to remove the dash and do the job correctly, but would like to know ahead of time what it entails, what is wrong, and to have the repair parts on hand to minimize down time. The compressor cycles a lot (at least that's the way it seems to me)- like ABOUT every five or seven seconds on then abot the same amount of time off. The gauge hooked up to the low pressure side of the system indicates that the compressor engages when the pressure hits the low end of the "good" zone, then the compressor runs, and then the clutch disengages when the pressure hits the high end of the "good" zone. The gauge is calibrated to show that this range is 25psi to 45psi. I can assume a lot of things from that, but what does it really mean? Anyone? I am addind this info to assist others as well as to learn what it happening... from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate > >The kit should have instructions on it. I would follow the gauge that > >should be included, but be careful not to overcharge. The 6 newton-meter is [quoted text clipped - 39 lines] > \__/olvo > 1993 960 Estate What you can determine from your cycling pressures is that the cycling switch is working correctly. What you can determine from the frequency of cycling is that the system is low on charge. It's hard to know just how much is needed to bring the charge up to full without a proper evacuate and recharge, but as you add some the cycling frequency should go down. When the A/C is working hard (i.e. hot day) then there should be no cycling. Add about another half pound and see if the cycling frequency goes down. If not, then you have other problems.  SignatureMike F. Thornhill (near Toronto), Ont. NOTE: new address!! Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) >What you can determine from your cycling pressures is that the cycling >switch is working correctly. What you can determine from the frequency [quoted text clipped - 4 lines] >be no cycling. Add about another half pound and see if the cycling >frequency goes down. If not, then you have other problems. Thanks for that reply, Mike. I did take the car for a short ride yesterday and the air conditioning is working much better after adding a few ounces (? a guess) of 134a. The air from the center vents was actually cold (was warm before) and the air from the side vents was actually much colder. The addition of a small amount of 134a made a big difference for me. I have come to the conclusion that using the low-side gauge on the Volvo is not a very accurate method at all for this job. Too many variables. The cycling frequency did get lower after adding some 134a but without knowing all the other factors and how they interact (air temp, humidity, etc.), there is now way to use that to accurately judge how much is enough or too much. I should also have weighed the can of 134a before adding so I could tell how huch I used. The can says 14ozs.(net weight) and I probably only added about two or three ounces (about 75 grams). Knowing that it should not cycle at all (or at least barely so) when the weather is really hot is good to know as well. Thanks again! Much appresicated! __ __ Randy & \ \/ /alerie's \__/olvo '93 960 Estate > >What you can determine from your cycling pressures is that the cycling > >switch is working correctly. What you can determine from the frequency [quoted text clipped - 32 lines] > \__/olvo > '93 960 Estate It's not just Volvo where using a low side pressure gauge is not an accurate method of filling. Because A/C systems all work on the same principles of physics, and pretty much copy each other in general design, all systems behave this way. Generally the accumulator will hold around a half a pound of refrigerant in reserve, so losing the first bit and adding the last bit doesn't affect performance. SignatureMike F. Thornhill (near Toronto), Ont. NOTE: new address!! Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) If you have a low side guage the pressure when the charge is correct should be 30-32 lbs. If it isn't cold then it is not enough but you see 30 lbs. because the orifice tube is clogged. Sometimes evacuating the system from the low pressure side will clear it but it is better to disconnect the hose on the dryer and clean and reinstall it. Use a new o-ring. That is a sign the compressor is on it's way out, but you may get years more service out of it.An oil charge with sealant is a good idea while you are at it. > So the air conditioning of my '93 960, R134a system is working but not > all that well. Cool, but not cold air. I thought that one of the home [quoted text clipped - 34 lines] > \__/olvo > 1993 960 Estate >If you have a low side guage the pressure when the charge is correct should >be 30-32 lbs. If it isn't cold then it is not enough but you see 30 lbs. [quoted text clipped - 3 lines] >the compressor is on it's way out, but you may get years more service out of >it.An oil charge with sealant is a good idea while you are at i Rod, see my response to Jeff's post in this thread and let me know what you think... from Randy & Valerie __ __ \ \ / / \ \/ / \__/olvo 1993 960 Estate |
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