No Air Conditioning - High Pressure on Low Side
#1
No Air Conditioning - High Pressure on Low Side
Hey folks, I was thrilled to discover the other day that my air conditioning was no longer blowing cold air. Despite the fact that it was only February, it's already too damn hot here in Florida. Either way, I set about trying to diagnose and fix this myself. At the local AutoZone, I hooked up AC gauges with the car on, AC engaged, fans on max speed. On the low side I got ~125 psi and on the high side maybe 155 psi. The compressor runs quiet, the clutch engages when the AC button is pressed.
I"m also dumb because I can't seem to find the dang PCV or dryer in the parts diagrams for my 2003? What the heck are these called? Can Anybody share the numbers and a source? I'm hopeful that the problem is in the valve or dryer, but am open to suggestions. Who's got an avenue for resolution?
AC Gauge Readings
I"m also dumb because I can't seem to find the dang PCV or dryer in the parts diagrams for my 2003? What the heck are these called? Can Anybody share the numbers and a source? I'm hopeful that the problem is in the valve or dryer, but am open to suggestions. Who's got an avenue for resolution?
AC Gauge Readings
#2
first port of call for me would be the expansion valve. its a cheap part that's easily DIY replaced.
of course, you'll have to get the system refilled properly afterwards, so i would purchase the valve and take it to a shop and have them fit it at the same time as properly vaccuming out the system. disconnecting high pressure lines is no joke, and you dont want a big lungfull or refridgerant, as well as it being pretty irresponsible to vent refrigerants to the atmosphere
at least the a/c is one of the few things on an s that isn't specialized. i'd have no problem with a fast fit type place doing it.
edit: useful thread https://www.s2ki.com/forums/s2000-un...valve-1197914/
of course, you'll have to get the system refilled properly afterwards, so i would purchase the valve and take it to a shop and have them fit it at the same time as properly vaccuming out the system. disconnecting high pressure lines is no joke, and you dont want a big lungfull or refridgerant, as well as it being pretty irresponsible to vent refrigerants to the atmosphere
at least the a/c is one of the few things on an s that isn't specialized. i'd have no problem with a fast fit type place doing it.
edit: useful thread https://www.s2ki.com/forums/s2000-un...valve-1197914/
#3
I'm guessing expansion valve as well. The drier is right where you hook up the high pressure line on the gauge. The drier is post condenser and would give you a high reading on the hot side if it were clogged.
If the expansion valve is allowing too much refrigerant into the evaporator you will get high low side pressure. Or if you have a bunch of air and moisture in the system as well. These cars are starting to show their age, a drier isn't expected to work for 15-20 years. Maybe in AZ or California where there's less humidity it could.
The expansion valve is behind the battery, the 2 AC lines terminate at the TXV right behind the 2 piece plastic cover on the firewall. Its held on by a 4mm allen bolt.
If the expansion valve is allowing too much refrigerant into the evaporator you will get high low side pressure. Or if you have a bunch of air and moisture in the system as well. These cars are starting to show their age, a drier isn't expected to work for 15-20 years. Maybe in AZ or California where there's less humidity it could.
The expansion valve is behind the battery, the 2 AC lines terminate at the TXV right behind the 2 piece plastic cover on the firewall. Its held on by a 4mm allen bolt.
Last edited by Slowcrash_101; 03-05-2023 at 03:10 AM.
#5
#7
Took the car to have the refrigerant removed yesterday and the shop was saying that because the low side pressure was bouncing around at 125, that the compressor was bad. So, I guess I'm in the market for a new compressor now, too. I've read to not get a remanufactured one. Anything wrong with a parts store compressor? Have folks had bad experiences with Autozone, O'Reilly, Rock Auto, etc. compressors?
I'm planning to replace the drier and expansion valve at the same time. I mean, hell, cheap parts that I've already got. Anything else to know about replacing a compressor? Should I replace all the schrader valves, too? Similarly bummed because the whole reason I took it to them was so that I could be a good little boy and properly remove the refrigerant, but they wouldn't take it, saying it was contaminated, so now I've just got to vent it, I guess.
I'm planning to replace the drier and expansion valve at the same time. I mean, hell, cheap parts that I've already got. Anything else to know about replacing a compressor? Should I replace all the schrader valves, too? Similarly bummed because the whole reason I took it to them was so that I could be a good little boy and properly remove the refrigerant, but they wouldn't take it, saying it was contaminated, so now I've just got to vent it, I guess.
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#8
Find a good used one, or brand new one, avoid the remanned ones. Also the low side will bounce around when you first start the ac system, it takes a while for the pressure to settle.
Also while one should be responsible for mother earth, sometimes accidental discharge of the system happens. Just make sure you vacuum the system thoroughly before recharging. Vacuum for 30 min at least, then let it hold vacuum for another 30 min. If it holds then you can charge it, use a scale and load by weight.
Also while one should be responsible for mother earth, sometimes accidental discharge of the system happens. Just make sure you vacuum the system thoroughly before recharging. Vacuum for 30 min at least, then let it hold vacuum for another 30 min. If it holds then you can charge it, use a scale and load by weight.
Last edited by Slowcrash_101; 03-10-2023 at 02:59 AM.
#9
Thought I'd issue a follow up post in case somebody comes by to reference this down the line...
I wrapped up the job this past weekend. While I haven't driven the car yet, I'm still calling it a success since I have cold A/C again! To get it done I ended up replacing the compressor (with a new one), dryer (drier?) and expansion valve all from Autozone. The parts were all Four Seasons branded stuff.
When replacing the expansion valve, it's worth nothing that it was much easier to get at everything with the battery removed. Also, twice, I was unsuccessful in reassembly by putting the o-rings on the valve itself. Once I switched to putting the o-rings on the male ends that the valve "plugs into" was I able to make a leak-free system. The reassembly of the lines to the valve was harder than it should've been. Not sure what I was doing wrong there, but I really had to get on them to get it all buttoned back up. ...I did take a bolt out of both the heat shield and the tube support to increase flexibility of the lines, but still.
Bolts everywhere took a good coat of PB Blaster/Kroil before breaking loose. Especially the allen head bolts in the expansion valve and compressor mounting bolts. ...but really, everything for me took a good soaking first. YMMV, of course, depending on how long it's been since anything has come apart.
To get to the compressor, I did go from underneath. While I think it might have been possible to do it by myself, it was a helluva lot easier with a 2nd set of hands (thanks Wife!) to get the compressor in and out. I had to remove the support bracket (three bolts) to get enough room to shimmy the old compressor out and the new one in. It might've been possible by myself, but a LOT of cussing would've been involved.
Other notes include extensive use of ratcheting wrenches and extensions to get at/to various fasteners. It can be pretty tight in there without removing the alternator and intake "stuff", but it's possible. Now, how long this repair holds, we'll see! Also, I added no PAG oil to the compressor because the sticker said it came pre-charged with 3 oz. That may end up dooming me, but I'm hopeful that it's close enough. Thanks for the help and references, I appreciate it!
I wrapped up the job this past weekend. While I haven't driven the car yet, I'm still calling it a success since I have cold A/C again! To get it done I ended up replacing the compressor (with a new one), dryer (drier?) and expansion valve all from Autozone. The parts were all Four Seasons branded stuff.
When replacing the expansion valve, it's worth nothing that it was much easier to get at everything with the battery removed. Also, twice, I was unsuccessful in reassembly by putting the o-rings on the valve itself. Once I switched to putting the o-rings on the male ends that the valve "plugs into" was I able to make a leak-free system. The reassembly of the lines to the valve was harder than it should've been. Not sure what I was doing wrong there, but I really had to get on them to get it all buttoned back up. ...I did take a bolt out of both the heat shield and the tube support to increase flexibility of the lines, but still.
Bolts everywhere took a good coat of PB Blaster/Kroil before breaking loose. Especially the allen head bolts in the expansion valve and compressor mounting bolts. ...but really, everything for me took a good soaking first. YMMV, of course, depending on how long it's been since anything has come apart.
To get to the compressor, I did go from underneath. While I think it might have been possible to do it by myself, it was a helluva lot easier with a 2nd set of hands (thanks Wife!) to get the compressor in and out. I had to remove the support bracket (three bolts) to get enough room to shimmy the old compressor out and the new one in. It might've been possible by myself, but a LOT of cussing would've been involved.
Other notes include extensive use of ratcheting wrenches and extensions to get at/to various fasteners. It can be pretty tight in there without removing the alternator and intake "stuff", but it's possible. Now, how long this repair holds, we'll see! Also, I added no PAG oil to the compressor because the sticker said it came pre-charged with 3 oz. That may end up dooming me, but I'm hopeful that it's close enough. Thanks for the help and references, I appreciate it!
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