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I'm having problems on my 01 S40 as my AC did turn on and off on idle.I did fill some refrigerant which fixed this but if I hold the RPM at or over 2K the system shuts off as the low side drops then turns on again when it raises over 30PSI .I'v got 42PSI on the low side on idle and at 2K it goes down to 28 when it shuts the compressor.I suspect the low side pressure switch might be tired wanna replace it but only pressure switch I find is the one on the dryer.It has 3 wire could it be a combo?Is the one I need to replace?
Your diagram agrees with what is shown on the dealer parts sites - that there is only 1 pressure sensor and its located by or plugs into the dehydrator (item 3 in the picture part# 8623270). On older models like the 850, the low pressure sensor is on the return line between the firewall and the low pressure port and there is a separate high pressure port. Did you measure the pressure at both the high and low ports to see if the high pressure is going out of range as well?
Your diagram agrees with what is shown on the dealer parts sites - that there is only 1 pressure sensor and its located by or plugs into the dehydrator (item 3 in the picture part# 8623270). On older models like the 850, the low pressure sensor is on the return line between the firewall and the low pressure port and there is a separate high pressure port. Did you measure the pressure at both the high and low ports to see if the high pressure is going out of range as well?
Yes I hooked up my gauges the pressure is all good otherwise.It shouldn't shut off at that pressure I'm sure.Do you know the actual min pressure on the low side?I'm having hard time believing that one sensor works for both low and high pressure on the same line..
Last edited by GerBeGurGya; Jun 20, 2020 at 07:07 PM.
Is it possible that the system is just low on gas? Sounds like that kind of symptom...
Yes it did seemed a little low hence I added some.Before I measured the low side on idle ~28PSI after it went to 42PSI.If I go any lower than that the system would reach low at higher RPM so right now I'v made a compromise so it will work most of the time.Went temp goes down to 54F I just know it could do a lot better.
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FWIW, I'll sometimes monitor the vent temperatures when adding gas to the A/C. I let everything stabilize, then add a little gas. If the temperature goes down, I add some more. I continue until the temperature doesn't go down any more (or even goes up a degree or two). As long as the vent temperature is in the low 40's or high 30's, I'm happy, and call it a day. Not overly scientific, but I can't imagine that I miss the optimum charge by too much that way.
FWIW, I'll sometimes monitor the vent temperatures when adding gas to the A/C. I let everything stabilize, then add a little gas. If the temperature goes down, I add some more. I continue until the temperature doesn't go down any more (or even goes up a degree or two). As long as the vent temperature is in the low 40's or high 30's, I'm happy, and call it a day. Not overly scientific, but I can't imagine that I miss the optimum charge by too much that way.
Yes thats how I know there is too much gas in there.Lower I go lower the temp gets but cant let out more as then the compressor will turn off even on idle.Instead of 42PSI what I run now on idle I should run 35-ish.I just need to know where is the low pressure switch is at so I can replace or bypass it.
Bubbles mean the system is low. Lots of small bubbles means very low. A few big bubbles means slightly low. No bubbles is full. You probably know this already....
Bubbles mean the system is low. Lots of small bubbles means very low. A few big bubbles means slightly low. No bubbles is full. You probably know this already....
Yes indeed I knew but when I added gas the temp from the vents went up by 15F and was still bubbling.Beginning to think if the dryer is clogged.Is that even possible?I have never saw one open I dont know whats inside.
have you ever recharged the system before? reason I ask is the refridgerant is both R134 as well as oil for the compressor - so when you recharge you need to check whether you are adding more oil. That said, the dryer is there to accumulate extra refridgerant during the cycles but most do have a filter for moisture and particles so its plausible to me that it could clog up. If topping off the coolant level doesn't restore your chill, it may be time for a proper system service ie replace the dryer ($100), expansion valve ($100), pressure sensor? ($100) new o-rings, dye test for leaks, then vacuum the system and add the correct volume. I'd say this will add up to a $600-700 job if you open the system up
have you ever recharged the system before? reason I ask is the refridgerant is both R134 as well as oil for the compressor - so when you recharge you need to check whether you are adding more oil. That said, the dryer is there to accumulate extra refridgerant during the cycles but most do have a filter for moisture and particles so its plausible to me that it could clog up. If topping off the coolant level doesn't restore your chill, it may be time for a proper system service ie replace the dryer ($100), expansion valve ($100), pressure sensor? ($100) new o-rings, dye test for leaks, then vacuum the system and add the correct volume. I'd say this will add up to a $600-700 job if you open the system up
Yes last summer I did a complete gas replacement and vacuumed the whole system before recharged it.I dont know where you are getting those prices tho.I see expansion valve for $15 same for the dryer.I dont see this valve in the engine bay is it inside the cabin under the dash?Anyway I thing its there and it is working as I measure 33F on the cold side at the firewall.I will replace the dryer for now and flush the system.If the dryer could clog up and it seems it could then would explain the drop of the low side below threshold as its surging for more and its not getting it.
Last time the person at AZ told me the oil needed is PAG 100 is that correct?
Last edited by GerBeGurGya; Jun 23, 2020 at 05:41 PM.
I was looking at tascaparts.com (a dealer web store)- a good way to get the Volvo part number and a good dealer price for genuine volvo. You can always shop for after market and save some coin but no guarantees on fit unless you know the OEM brand.
I was looking at tascaparts.com (a dealer web store)- a good way to get the Volvo part number and a good dealer price for genuine volvo. You can always shop for after market and save some coin but no guarantees on fit unless you know the OEM brand.
I'm shopping for this car from this site since I own it never had a bad experience.Dealer will not see a dime from me ever.Thanks for the input.
AC low pressure switch
