my temps now are 17 deg at idle, as the revs go up and the fan speeds up the temp drops after about 5 sec. So clearly not enough air getting through.
Got the car back just now. Air Temp at the vents is 7 degs after only a few minutes As Promised Jay Kay's Auto Electrics and air conditioning 48 Moss Street Slacks Creek. 3209 1422
Hmm, when i got my a/c serviced about a year ago they registered 3 degrees at vents, @ 10 mins. Maybe also to do with climate here or something. But either way, anything around these temps means healthy a/c. btw, good to see you also got your a/c issues sorted out too Greg. Good time of year to have it working A1 me thinks.
He said 6-7 degrees is ideal. Any colder and you risk icing the evaporator I guess. Was only a 10 minute trip home, so on a longer trip it may have got a little cooler who knows
So what is wrong with my system then with new gas and it's still only 17C. I drove home sweating with the air con flat out, and $85 poorer.
That was my next thought, I was going to run the car cold with the air con on cold and see how cold it is, if it's cold before the thermostat opens then I know its the heater valve.(easier than bypassing)
So in answer to a question I had yesterday pondering a solution the cold ac air passes over the heater core?
Beware...Looooong post! Ok a couple of points here need clarifying. Bit of a long one!!!!! Sorry in advance! A quick refrigeration rundown. Compressor compresses refrigerant gas and is cooled and condensed to a high pressure liquid. In a condenser core (hence the name)! Works the same as a radiator really just does a slightly different job. High pressure liquid passes thru the receiver/dryer (round can thingo often with the sightglass) It works as an accumulator/dampener of sorts, kinda storage bottle and has a mesh screen to trap any debris and has a bag of silica-gel in there to remove any moisture. Receiver dryers must be replaced any time the system is opened to atmosphere as they are a welded item and the bag of silica gel cannot be replaced. The high pressure liquid then travels to the Thermal Expansion valve (TX Valve, usually mounted right on the front of the Evaporator core) Its just a variable orifice and the high pressure gas expands across the TX valve becoming a low pressure, low temperature vapour. (Adiabatic change). The cold gas is "evaporated" in the evaporator core and returned to the front end of the compressor in a low pressure/low temp state via the larger "suction" line. The TX valve also maintains a balance between suction and discharge pressures. Compressors are (usually) a positive displacement multi-piston pump and will pump sky high pressures if the suction line to the pump is not controlled to maintain balanced system pressures. Either the belts will screech/break, the clutch will slip and eventually weld itself together or the rubber discharge line from the compressor will blow off/rupture if a TX valve becomes blocked on the liquid side. Its a tiny orifice in there as well! Cleanliness is the key when fiddling with refrigeration bits. Reason for filter screen in dryer. TX valve dramas can be a total arse ending up in hundreds of dollars in labour alone just to get the bastard out, let alone buy a new genuine item as mentioned in a previous post. Id expect his job to come to........christ its going to hurt!!!!! Moisture in the system from a badly maintained or dodgey initial fitting can freeze immediately in the TX valve blocking it temporarily. This can sometimes explain AC systems suddenly going hot and then cold again in succession. Moisture also leads to corrosion of internal parts and this corrosion can circulate around a bugger things up. Blockage on the suction side will simply stop any compression at all and the usual result is a much overheated and eventually rooted compressor after prolonged use. The cold suction side returning gas also cools the compressor. Usually a seizure due to lack of cooling and returning oil. The "old" type of gas is R12 and was known as "Freon" . Its a universal refrigerant and supposedly contributes to the depletion of the ozone layer. Not quite that simple but another story. The "New" gas is R134a. The new gas requires some minor changes to the system for compatability. However, R134a usually runs higher compressor "head" pressures and so draws some more power from the engine compared to R12. Evap. cores are placed in FRONT of the heater cores. If there is the slightest leak in the heater valve, the vent temp will rapidly climb. It is incredibly difficult to remove heat from air but bloody easy to add it. Id say the vast majority of AC vent temp issues are as a result of the heater valve slightly leaking and taking the "edge" out of the system. Sometimes just a fine adjustment of the heater tap cable is enough to solve it. The gas never really "wears out" (unless it is contaminated). The age old question of how often to run an AC system comes up regularly. To make sure, run it at least EVERY TIME YOU DRIVE the car! A little used trick is to run your AC when the windows are badly fogged up in shit weather. The AC will clear the screen in a fraction of the time the demister vents will. Even just for a few seconds at startup to distribute the lubricating oil around the system and to force the liquid thru the reciever/dryer to help remove any moisture in the system. Refrigerant oil is a very pure mineral oil which, unlike motor oil, does not "stick" to AC components. After time the oil simply runs off/dries out/whatever you like and the inner component surfaces can corrode, especially if the system has been opened to atmosphere and not been vacuumed down for enough time prior to re-gassing. The compressor shaft seal is very similar to a water pump dynamic seal with a spring loaded carbon ring O-ringed to the compressor shaft and a static ceramic ring O-ringed into the compressor snout. There is only a thin ring of carbon running against the highly polished ceramic ring to seal off the gas. If this surface dries out gas can leak over time and the surfaces of the seal can be damaged on initial run after prolonged inactivity. Rust can also form under the O-rings on the shaft. This usually equals a rooted compressor. It will always leak gas and the shaft cannot be repaired. Not cost effectively anyway. This type of shit also happens when the system looses all pressure and is left for prolonged periods of time. Repeated heat cycles and the system open to atmosphere sucking in moisture and oil fumes as it cools can render a system a complete PITA for evermore! This is also true of second hand system bought out of wreckers, old write offs and so-on. You never seem to be able to get them to hold gas for any extended length of time and blockages/failures due to dust, moisture and dirt are a tiresomely common occurrence!!!!! If your AC system slowly looses its punch, the first thing is to check whether there is sufficient gas in the system. Have a look at the sightglass with the car idling and AC on and look for the liquid. Its quite obvious. Bubbles is quite normal. Occasional splashes chuffing past the glass is indicating too low gas level. If you cant find/see the sightglass then grab the metal part of the suction line on the the compressor. It should be extremely cold. If all is in order then the next thing is to look for ANY hot water leaking past the heater valve. Here you need to compare the heater inlet and outlet temps. Best of luck depending on the car and where the metal parts of the hose connections are. As stated in a previous post, vent temps should never go under 4 to 5 Deg C. Evaporator cores will condense water out of the air passing thru it (hence the dripping cold water under the car with the AC on) I seem to recall the figure somewhere near 30% per pass of the core.......not sure now...neway, and this water can freeze on the core tubes. Ice is actually a surprisingly good insulator and frozen tubes result in a remarkably inefficient AC system. All AC systems employ a thermostat poked into the evap core. Some are funky electronic sensors and many are just fixed mechanical thermostats with an temp. trimmer. Many a suspect AC system has had some smart-alec incompetent get the screwdriver out and "tweaked" the thermostat chasing colder vent temps and the inevitable result is a frozen evap. core after prolonged use. They all loudly deny theyve adjusted it tho.......clowns! Regardless of the system, be it plain old AC or climate control, the compressor will kick in and out to maintain evap. core temps just above freezing. If your system suddenly goes hot, switch it off immediately and dont run it again until you find out WHY it went hot. Many systems are protected by thermal overtemp, pressure switches and so-on. However, all these gizmos can, and DO fail and the inevitable result is a fckucked compressor if a hose blew and all gas and oil is lost and the compressor is left to run its guts out. It will last a similar amount of time as your exensive engine will run with no oil and thats usually not too long. I cant speak for the Zed but just about every car ever made with a thermo cooling fan as stock will have provisions for the AC system to cut it in and out independent of the water cooling temp. OR have its own dedicated AC fan controlled by the compressor clutch pullin wire. Viscous coupled fans tend to work ok. Compressor discharge temps AND pressures can rise dramatically to alarming levels if the AC system is run hard with no air across the condenser core even on a cool day. I cant speak for R134a but the old R12 had an interesting property where the discharge pressure and temperature are pretty much proportional. Bottom line, for best AC performance, the more/bigger thermo fans the better! OK, the AC system only has so much capacity and regardless of the temp setting, it will only cool down to the limits of its capacity. So setting the thing at bloody cold will NOT cool the car "faster", it will just continue to cool down past a comfortable temp and so make you "feel" cooler. Women seem mostly prone to this furfy......... sorry ladies, way it is! For best results, run the fans on high and the recirc valve OPEN. This brings in fresh air to help force out the very hot air in the cab and then close the recirc valve once things become tolerable in there. As mentioned before, AC removes a significant amount of moisture from the air each pass of the evap. core and so prolonged driving with the fans on high and the recirc valve closed usually results in extremely low humidity. Nice and comfy but often scratchy and dry eyes. Really prolonged AC use in recirc mode in a well sealed car can also result in depleted oxygen levels in the car and added drowsiness.....dont laugh! Even my truck climate control will automatically open the recirc valve after 30 minutes for this very reason! Its wise to open the recirc valve every so often during a prolonged run to introduce some humidity and oxygen. There you go gentlemen. Long winded but there should be something there for some of you!!!!!! L8tr E
i bought my car with recipts of a $1200 ac overhaul new compressor fittings and gases anyway the aircon is pretty sad it was done july 2008
cool "no pun intended" I replaced the compressor myself but made sure when the old one was removed the pipes were covered with glad wrap to prevent foreign matter. Sould I have had the dryer replaced then? Is this the cylinder at the front of the car? I didn't ask what gas was used, what would happen if my car was charged with R134a but should have R12? how about crimping the heater hose in the bay temporarily to determine if I have a leaky heater? I can't think of an easier simple way. should my system have been "vacuumed down" (what is this) after I installed the compressor? Thankyou I've been trying to explain this above to some people. I can vouch for the drousyness, my brand new hilux used to make me sleepy. Chrispy and I were talking about the timed recirc thing today, he said it was 15 mins before it turns off, so it's to stop you sleeping:biggrin:
i took mine in to be checked and he told me i had a leak but couldnt do anyhtign about it becouse he couldnt get to it and didnt know how to (-_-') ****ing ZX's.... he didnt charge me for it and now i know i got a leak, soo,, I dono what to do from here
perhaps just call around ac shops and tell them where the leak is? Or some people here might suggest some places to go.
yer i think im going to look at some other places that do car mechanics and AC. He couldnt even tell me where the leak was ay, he had no idea.. "couldnt see in and couldnt fit a jack under" luckily he didnt charge me, i woulda been quite angry.
Temp readings Well done, this is my medium for testing medium-rare and rare air conditioning problems. LOL Anyway, here is the digital temp probe (all be it a roast meat thermometer) showing 6 degs at the vents. My dilemmas continue. Round 1 = Nissan install a supplied receiver dryer and compressor over 1.5 days, charge $718 (result no fix). Nissan refuse to supply the evaporator (too hard perhaps???) Round 2 = Found Jaykay Auto electrics, they install supplied evaporator / Tx valve over a 2 day period (result works perfectly again), but gas leaks out over a 6 day period. Round 3 yesterday and today try and locate leak (leak not found either with the sniffer or dye leakage) regas with an increased amount of dye, so if it leaks out again it will be easier to spot. He ran for 2 hours yesterday with air con running leak couldn't be found. Hopefully that'll be it, else next week I'll be back there again.
Sounds like a similar process to how i cook a medium-rare CAS unit in the oven for 15mins. Well that sounds strange, all of a sudden the leak has stopped. As Rob said, a good cruiZe on a hot summers' day will tell a lot. Lets hope it's fixed for good though. Nothing worse than the A/C not working in middle of summer!
