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Car Forum / Volvo Cars / July 2005850 AC - A different problem?
The AC on our '96 850 (with fancy climate control) works great for about 5-10 minutes after you turn it on, after which it blows warm air. The dealer couldn't find any leaks after injecting dye into the system and looking for it under UV. I don't think the climate control system is turning off the AC because it's still running the fan at full on. What should I look at next ? Thanks, as always, in advance, ----- -RL > The AC on our '96 850 (with fancy climate control) works great for about > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 8 lines] > > Thanks, as always, in advance, Is the evaporator drain plugged? On very humid days you should be able to see the water drip and run out from underneath the middle of the car. > The AC on our '96 850 (with fancy climate control) works great for about > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 12 lines] > > -RL Robert, Could be Evaporator icing........ Dale Peterson I was thinking it might be something like that, icing over of the evaporator. That isn't the usual sign of failed evaporator, is it? Is it fixable? ----- -RL >> The AC on our '96 850 (with fancy climate control) works great for about >> 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 16 lines] > Could be Evaporator icing........ > Dale Peterson >I was thinking it might be something like that, icing over of the >evaporator. > >That isn't the usual sign of failed evaporator, is it? If icing was the problem, the airflow would go way down. Also, icing is usually a sign of low refrigerant charge (At lest it was on my home's system) If it's the overtemp switch, the cooling will come and go, over about a 5 minute cycle. I didsonnected the switch on my 94 years ago, and haven't had a problem since. To reply, please remove one letter from each side of "@" Spammers are VERMIN. Please kill them all. > The AC on our '96 850 (with fancy climate control) works great for about > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 12 lines] > > -RL Doesn't the '96 have the infamous compressor overtemp cutout switch? IIRC they got rid of it in later years, but earlier 850s had the troublesome switch on the rear of the compressor. They didn't seem to save compressors, just cause symptoms like yours. The gurus will probably provide the details. Mike >>The AC on our '96 850 (with fancy climate control) works great for about >>5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 19 lines] > > Mike Yes but if the car has a pollen filter check this also this will keep the evaprator from breathing if it is clogged  Signature"*-344-*Never Forgotten" Is for the New York City Firemen who lost their lives on September 11,2001. The official count is 343, but there was also a volunteer who lost his life aiding in the initial rescue efforts. And I will never forget them as long as I live, nor should any American. Based on the symptoms, I'm guessing it's the overtemp switch on the compressor. Thanks to all who responded. Is the overtemp switch a little square molded yellow thingie, about 1cm square sitting atop the compressor? Thanks, -RL ----- >> The AC on our '96 850 (with fancy climate control) works great for about >> 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 20 lines] > > Mike > Based on the symptoms, I'm guessing it's the overtemp switch on the > compressor. Thanks to all who responded. [quoted text clipped - 5 lines] > > -RL The cutout has 2 wires going into it and is mounted on the back (non drive end) of the compressor. SignatureMike F. Thornhill (near Toronto), Ont. Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) > Is the overtemp switch a little square molded yellow thingie, about 1cm > square sitting atop the compressor? No, it's underneath and round the back, tricky to get to. David. >> Is the overtemp switch a little square molded yellow thingie, about 1cm >> square sitting atop the compressor? > >No, it's underneath and round the back, tricky to get to. > >David. It has two wires, with male and female connectors, which connect between the car's wiring harness and the clutch wire. All you have to do is unplug the two connections, and plug the clutch wire directly into the harness wire. The connectors have split plastic covers on them which keeps them clean and secure. Having long, skinny arms helps. To reply, please remove one letter from each side of "@" Spammers are VERMIN. Please kill them all. > clean and secure. Having long, skinny arms helps.=20 Ah it was the skinny arms that I fail on and besides, I had the compressor in my hands at the point when I decided to bypass it. I was already doing the clutch shims. David. > The AC on our '96 850 (with fancy climate control) works great for about > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 6 lines] > > What should I look at next ? Clutch gap. I've just done mine during the heatwave and bypassed the temp cutout at the same time. Gap should be 0.3 to 0.5mm and mine was something like 1.2mm. It's a bit of a pig to do as I found that I had to remove the ECU's the ECU box, the belt, the power steering pump, the alternator and the brackets for same before I could get to the compressor, then the compressor has to be unbolted to get enough room to take the pulley off just so that you can remove a shim. Still it was worth it in the end. David. > > The AC on our '96 850 (with fancy climate control) works great for about > > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 20 lines] > > David. Another cure for the clutch gap is to put a relay in the circuit. This gets a higher voltage to the clutch winding, delaying the repair for ??? Disconnect the wire that leads to the compressor clutch. The wire that's part of the compressor goes to pin 87 on your relay The wire that's part of the engine harness goes to pin 86 on your relay Pin 85 on the relay goes to ground. Pin 30 goes to a fused power source. This circuit only draws about 5 amps. SignatureMike F. Thornhill (near Toronto), Ont. Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) > Another cure for the clutch gap is to put a relay in the circuit. This > gets a higher voltage to the clutch winding, delaying the repair for > ??? Yes but the amount of effort to do that (and extra pennies) :) when all I had to do was spend several hours doing it properly just doesn't compare! (yeah it's a pig but I like to do things once). David. > > Another cure for the clutch gap is to put a relay in the circuit. This > > gets a higher voltage to the clutch winding, delaying the repair for [quoted text clipped - 7 lines] > > David. While I agree "your" way is the better way to do it, "my" way has some benefits. Volvo added a relay for this function on the S/V70 in 1998. You can do this repair without crawling under the car, or removing any other parts, a big benefit if it's hot, you don't have much time, or don't have the tools/skill. As a disclaimer, I don't know how much longer this will enable the compressor to work. SignatureMike F. Thornhill (near Toronto), Ont. Replace tt with t (twice!) and remove parentheses to email me directly. (But I check the newsgroup more often than this email address.) > As a disclaimer, I don't know how much longer this will enable the > compressor to work. That's the thing and with my gap at 1.2mm already, I was going to do that because the problem only manifested itself during the very hot days and we don't get enough over here to keep doing trial runs to see if the fix worked and when it is hot enough, it's a bummer to discover that it didn't. Hence, full job for me. :) David. Recall that our symptoms are that it works beautifully for about 10-15 minutes and then just blows warm air. When this happens, the clutch is clearly not spinning. Well, we had it at the dealer this week for the timing belt replacement (and transmission flush), so I had them look at the AC too. Based on the good advice from this board, I described all the symptoms and suuggested they look at the overtemp switch and clutch gap. The dealer determined that we need a new evaporator ($1350). This seems unlikely to me, given the symptoms. Signature----- -RL > Recall that our symptoms are that it works beautifully for about 10-15 > minutes and then just blows warm air. When this happens, the clutch is [quoted text clipped - 8 lines] > > This seems unlikely to me, given the symptoms. I agree completely. Evaporator problems were legion for the 850 all right, but they were pinhole leaks and produced low-refrigerant indications - consistently poor cooling and short-cycling of the compressor. Mike > The dealer determined that we need a new evaporator ($1350). > > This seems unlikely to me, given the symptoms. Agreed. If the evapourator has sprung the 850 leak then the refrigerant would leak until it just didn't work at all. If it works for a while, every day then it's not the evapourator! David. > Recall that our symptoms are that it works beautifully for about 10-15 > minutes and then just blows warm air. When this happens, the clutch is > clearly not spinning. It's dead easy to measure the gap yourself, if you don't have a feeler guage just go to any car parts place and buy one, then just select strips until when pushed between the gap, they just bind. It should be something like 0.3 to 0.6mm (or thereabouts), like I said, mine was 1.2mm. David. How do you change the air gap? I've got a VW Passat with similar symptoms, and am planning tomorrow to try a bypass wire to test with a solid 12+ volts. If it is the clutch gap, how would it be adjusted? ( Sanden compressor) >> The AC on our '96 850 (with fancy climate control) works great for about >> 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 20 lines] > >David. Ron/Champ 6 1963 8E5 Champ (Champ 6) 1962 Lark Daytona Convertible On eBay now...(Boomerang) 1995 VW Passat (Vanilla..yuk) 1994 Volvo 850 (Tilley) 1973 Volvo 1800 ES (Hyacinth Bucket) > How do you change the air gap? I've got a VW Passat with similar > symptoms, and am planning tomorrow to try a bypass wire to test with a > solid 12+ volts. If it is the clutch gap, how would it be adjusted? ( > Sanden compressor) The amazing power of Googling for "sanden compressor clutch gap" yields the second link as the Sanden service manual http://www.sanden.com/support/pdf/sd7servicemanual.pdf Basically, you measure the gap first, remove the clutch then remove the right number of shims (using your measuring tool such as digital caliper/micrometer) and then put it all back together again. The notes say you need to use a clutch puller which you might be able to hire or slip some cash to the local AC guy etc. I got mine off by just inserting 3 x 5mm screws and progressively tightening them. They push against the pulley below which isn't quite the idea but it works. :) David. > How do you change the air gap? I've got a VW Passat with similar > symptoms, and am planning tomorrow to try a bypass wire to test with a > solid 12+ volts. If it is the clutch gap, how would it be adjusted? ( > Sanden compressor) Incidentally, the clutch gap problem is usually only when it's very warm say got to the 30 deg C type weather and it works for the first 10 mins or so but then the extra heat increases the resistance of the windings such that there's not quite enough magnetic force to pull the plate in from the increased distance. If it's not working when cold then it's unlikely to be the clutch gap. David. > The AC on our '96 850 (with fancy climate control) works great for about > 5-10 minutes after you turn it on, after which it blows warm air. [quoted text clipped - 8 lines] > > Thanks, as always, in advance, My 960 did exactly the same thing, and it turned out to be a $15 temp sensor at the rear of the engine. Don't know whether the 5-cyl version of this engine has a similar sensor / Motronic setup.
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