Model: Impreza STI Spec C
Engine Size: 1994
Refrigerant Type: R134a
Country of Origin: Japan
I realised that at times (mostly after i parked my car overnight or for a few days) when the aircon is turned on, and i physically hear and see the aircon kicking in, the cold air is very much delayed. I timed in just now, it was a good 30 seconds before the air that comes out from the vent starts getting colder.
Heres the thing, my car has been kept in storage from new unregistered for over 2 years. I don't know if i'm imagining things, or if it's true that some parts (aux parts) don't like such lengthy storage times?
It's only done 3000 miles.
And a few months ago, this was the issue -> http://www.autoacforum.com/messageview.cfm?catid=2&threadid=21605&FTVAR_MSGDBTABLE= I've since gotten a new compressor replaced under warranty.
Oh, and this delay in cooling problem was there even with the previous compressor.
What could be the cause of it?
Thanks for any help fellas!
30 seconds for the air to drop in temp is not totally out of line. After a few minutes is it nice and cold at that point? Knowing it has the proper level of refrigerant would be the first thing to check.
Question is, was it that way when new? R-134a does tend to leak out, especially if you don't run the car, oil around the compressor seal tends to dry out.
Another thought with Subaru's using an economy position on the climate control if yours has that. Plays games with the evaporator thermal sensor, instead of the usual 33-39*F limits, it is raised to something like 38-45*F limits that is controlled by a relay. Could be a loose connection or dirty contacts.
For me this question is pretty tough to answer. It cools but not as fast as I want. I would need some pressure readings idle/1500 plus know the refrigerant level for starters. Then would need to run the system and monitor the performance.
Was just speculating that can be done on a board. With a vehicle in my garage, go through all the steps to properly diagnose the system starting off with the compressor clutch, coil test, gap, running the engine to check on operating pressure over the entire speed range. And even bypass the electrical/electronics by directly hot wiring the clutch coil to be satisfied the mechanical condition of the vehicle is par. With intermittent operation can also be mechanical, your symptom is suggesting a stuck TXV, but again, only speculation, gauges on the vehicle would verify that.
With satisfaction of a properly operating mechanical system, can throw in cooling and the blower motor fans as well, then its electrical troubleshooting. Your symptom may also be an improperly adjusted clutch gap. These things have to be checked.
Since I am also seeing part of the world now, can't even assume a symptom based on USA experience, even with the same make and model, differences occur between vehicles made for the Japan or for the USA.
I did hear in Japan, once an engine hits 30KM, could be 30K miles, many Americans do not know the difference between a kilometer or a mile, that to meet Japan emission requirements, you have to install a brand new engine in your vehicle. Is this true?
Assuming the compressor really does engage as soon as you press the button, it could be a balky TXV getting stuck closed overnight. Or something in the compressor where it turns but does not pump. The sound you hear is the refrigerant starting to flow. You would need to measure the pressures during that 30 seconds while it is not cooling to confirm that, and also see if it's a TXV or compressor issue. Sounds like there's only one chance to make that measurement before it starts working normally.
Intermittent problems are hard to diagnose. If you take it to a garage they'd have a hard time replicating the problem. It'd be better to use your own gauges and test it yourself.
Edited: Sun January 23, 2011 at 8:40 AM by mk378
How would replacing a compressor correct a sticky TXV problem?
I am also here to learn.
Was a time in my life where I could do anything on a vehicle, overhauling an engine, rebuilding a manual or automatic transmission, differential, brakes, suspension, body work, painting, reupholstering, etc. But AC was a complete mystery, watch a pro do it, said I can do that, read books on the subject, and purchased a set of manifold gauges, and a vacuum pump. Was a bit nervous at first but that like anything else became old hate. That was like 46 years ago. Watch a pro.
Course things are a lot different today, started in 1993 when the government got involved. Still not an ounce of data anywhere if they have made any improvements, in my humble worthless opinion, they sure made one hell of a big mess. Should of just stick with extra-martial sex, that they are good at.
Haha Nick, showing your age ole buddy. I started MVAC at around 13... the old A6, A4, monster RV-2, POA, VIR, EEVIR, STV, vacuum operated climate control. It was more out of necessity, because my parents spent a fortune having a pro replace each and every A/C component on our 1973 Olds 98 Regency and still had no A/C - and I couldn't live without A/C.
Mom asked if I thought I could fix it, and I told her with a small investment in A/C tools and books, I was confident I could. Dad gave the green light... and I think the green backs too.
After a few weeks of reading, and lots of live testing on the big Olds (probably burned a whole tank of fuel), I found the problem was the TXV sensing bulb wasn't tightly clamped to the evaporator outlet - it was just sloppily stuck in the insulating goo. I cleaned up the sensing bulb and evaporator tailpipe of the black goo, installed new clamps, tightened the bulb securely to the evaporaor tailpipe, put on new goo (neatly), adjusted the charge - and viola - normal pressures and ice cold air around 35F from the vents. And the rest is history...
Really missed you JJM, are you a daddy now?
Yes, AC systems, once you know the theory of operation is fairly simple, evaporator and condenser is tantamount to a heater core and a radiator. Has a mechanical pump of either the vane or piston type. Orifice is tantamount to the nozzle of a spray can, and if you vary the pressure on the button, you know what a TXV does, except it has feedback. Accumulators or receivers are reservoirs for the excess and also provide a buffering action. Like electrical, can't see what going on, so you have to rely on gauges. Fortunately for me, electronic control came naturally. And when working on any vehicle, become accustomed to inaccessibility.
Government interference sure didn't help, still no statistics as to whether they have any good or not, but sure made a long time procedure very expensive. From my point of view, they made one hell of a big mess in this field of endeavor. And created a lot more problems than solving any.
Yesterday, the relative positions of the axis of rotation and orbiting position of this earth corresponded with a time when I was dumped on this earth. Really had no say on this matter, just asked, where in the hell am I. If given a choice, would have picked a time without so many wars, energy crises, job exportation, and idiotic politicians that think they know what is good for us. Read someplace, we are supposed to be a government by the people.
Perhaps it is being born with an urge to have a high quality of workmanship, not finding that in the AC world was key motivation to do it myself. Wish I could have done my carpal surgery myself, just suppose to clean up the area compressing a nerve. But learned later, my nerve was severed losing the loss of my key tool for almost a year now. But that never is growing back and celebrated two weeks ago that I could finally clip the fingernails on my left hand. But we have strong laws preventing entering that endeavor and see similar laws entering in many other areas of the chores we could do for ourselves.
America was once a country of individual freedom, innovation, and men that could carve out a forest for a place to live. Still let me nail a board, but with some idiot building inspector looking over my shoulder. And believe me, this guy is an idiot like the rest of our leaders. Treated more like sheep today than individuals, I don't like that. Never was such a thing as socialism or communism, was all dictatorships, and we definitely have that here as well.
Hi Nick, i thought the TXV is something inside the compressor. Just learnt that it is inside the cabin for my car. Would checking the pressure during those 30 secs or so point to a faulty TXV?
Yes you need the pressure test. There are two major causes for what is happening and a pressure test while it is not working will differentiate them:
Compressor spins but doesn't pump (for a while). In that case the pressures won't change much after the compressor engages. I think that old Subarus used a rotary vane compressor that was prone to this problem because the vanes get stuck in the rotor, not sure if it's still in the newer ones.
TXV stuck closed (for a while). In this case the compressor will raise the high side pressure and lower the low side like it should, but it will soon starve for anything to pump due to no flow through the TXV and evaporator. The low side will go real low, possibly into vacuum, i.e. below zero psi.
Edited: Tue March 01, 2011 at 9:52 AM by mk378
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