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Question on 92 740 A/C......

I tried a charge with Dura-Cool. I am not getting much cooling at all from the A/C. None before (there was a leak on the condenser), and little after. There is enough that at night when the outside temp is in the 80s you are cool, but it is overwhelmed by humid mid-90s weather in the daytime. I didn't replace the accumulator before recharging. ALso I was told that the orifice tube might be clogged up. So I have an accumulator ordered (along with the AMM) and also a new orifice tube. Will pump it down again and refill with R-134 this time.

ANother problem with the A/C is that the blower puts out a puny volume of air. I know it is rotating freely. I know it is controlled somehow by computer, because every time you go up even a slight uphill grade (or accelerate), the blower cuts back and there is practically no air blowing out the vents. Also the compressor is cut off under load. I would really like to try disabling this feature and see if car still performs OK, because it makes it get even hotter. I ckecked the voltage to it when it is going "full blast" and it is getting about the full system voltage.....maybe it just doesn't blow nearly the volume of air that a modern sedan does. But I don't know, since I don't have another 740 to compare with. Could I get some other more powerful motor for more air volume? How can I check to see of there is some restriction of the air inlet to the blower? I think there is a vacuum operated door, but maybe it is a hot/cold blend door on the outlet side of the blower. ALso, I need to know where the orifice tube is installed....I don't have a clue where to find it. Its probably not the fault of the Dura-Cool, but there is some other issue with it.

Thanks, Geronimo

Reply to
geronimo
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It's probably a clogged orifice, while you've got the system open, disconnect all the joints one at a time and replace all the O-rings, if you're gonna do it, you may as well do it right. Charge with the correct weight of refrigerant and it should work well, mine blows icy cold air when it's 90 outside on the highway.

Reply to
James Sweet

Reply to
geronimo

It's in the liquid line right at the firewall, pull the fitting off and you'll see it stuck in there, just pull it out with some long nosed pliars.

Reply to
James Sweet

Another ac question.....Just in case I have too much oil now in the system, I think I should drain it at the lowest point as much as possible before evacuating the system. I suppose being over-serviced with oil would reduce the amount of refrigerant that it will take, and so could cause poor cooling as well. So if I put 33 oz (nearly 3 cans) of R134 into the system, how much oil should I put in? I have purchased only two cans of refrigerant, which I think is nothing but refrigerant.... so if I buy another 12 oz can with oil, will it be enough? I have done a couple of recharges, the first with oil, and I never really drained the original oil out...so that is why I am thinking I had better really empty the system completely this time, to ensure the full factory charge of refrigerant will go in. I am also guessing that I will need to open a low side line at lowest point as well as a high side line at lowest point...right? Thanks, Geronimo

Reply to
geronimo

If you never drained the mineral oil out before converting, you likely have a real mess in there now. R134 reacts badly with mineral oil and breaks it down. You should definitely remove the compressor, drain all the oil, then flush out the lines, evaporator, and condenser with refrigeration solvent.

IIRC the oil charge is something like 8oz, I found the Volvo retrofit instructions online somewhere when I did mine years back.

Reply to
James Sweet

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