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Aircon kicks in, but cold air is delayed?!

Suberman on Fri January 21, 2011 3:08 PM User is offline

Year: 2007
Make: Subaru
Model: Impreza STI Spec C
Engine Size: 1994
Refrigerant Type: R134a
Country of Origin: Japan

Hi fellas,

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!

TRB on Fri January 21, 2011 8:06 PM User is offlineView users profile

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.

-------------------------

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Suberman on Sat January 22, 2011 2:30 AM User is offline

Quote
Originally posted by: TRB
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.

I think it's not quite right? Because it's not constant. Sometimes the cold air comes on immediately. Also, i've owned 3 Subarus, and none of them had this problem.

Could a slightly low level of refrigerant cause this? The refrigerant was supposedly evacuated and recharged to spec when the compressor was replaced by the dealership.

NickD on Sat January 22, 2011 5:28 AM User is offline

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.

Suberman on Sat January 22, 2011 8:44 AM User is offline

Quote
Originally posted by: TRB
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.

Yes, after the cold air comes on, it stays nice and cold thereafter.

Suberman on Sat January 22, 2011 9:04 AM User is offline

Quote
Originally posted by: NickD
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.

I don't remember it doing this when i collected the car. But i do remember that this problem was there when the old compressor was acting weird (link on 1st post), it SEEMS to be getting more frequent now. Compressor has been replaced once, so it's not that then.

Yes, mine has climate control. What is that evaporator thermal sensor thing that you mentioned? What difference does that temperature range do?

Thanks for the reply Nick.


TRB on Sat January 22, 2011 9:35 AM User is offlineView users profile

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.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Suberman on Sat January 22, 2011 3:04 PM User is offline

Quote
Originally posted by: TRB
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.

Appreciate your help thus far mate!

One more thing, (not sure if this would help you narrow it down) It seems to only happen after i park the car overnight. You can actually hear (what seems like) some form of gas release (like the refrigerant) is being released into the system after about 30 secs or so then the air gets cold. If i only park it for a couple of hours or so, it seems fine (air is cold immediately)

With you advicing that i get some pressure reading, would a lack of refrigerant cause something like that?

NickD on Sat January 22, 2011 3:35 PM User is offline

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?

mk378 on Sun January 23, 2011 8:35 AM User is offline

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

Suberman on Wed February 02, 2011 7:39 AM User is offline

Quote
Originally posted by: NickD
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?

Hi Nick, sorry for the delayed reply. Work was just piling up. Anyway, i've spent the past week or so logging down the problem.

Everything was working fine for the past week or so. Cool air immediately (within 1 sec or so) when i switch on the A/C. Even though the usage frequency of the car was more or less the same. (i.e. 2-3 times during that week) So each the car was parked, it will be 2-3 days before i start it up again. And everytime the aircon worked like it should.

I was almost happy to think that somehow the problem went away as the car was used more frequently. Until this morning! Drove it to work. ARGH!! No cold air for the 1st 30 secs or so!! I realised the problem is very much still here!

Restarted it about 5 hours later, and no cold air again! This time it took almost a full minute for the cold air to be pumped into the cabin! It usually only happens when i park the car overnight or for a few days. I've never experience it when the car is only parked for a few hours.

With regards, to your suggestion of diagnosing it step by step is going to be a challenge for me as i'm not particularly good with these things. I'm trying to narrow the possibilities down so i can get an aircon shop take a look at it?

The TXV is in-built in the compressor? I doubt that's causing it because like i said, the compressor was replaced under warranty last month, and this intermittent delayed cooling has been there from before.

Would low refrigerant cause something like this?

And no, i'm not from Japan, i selected Japan because i thought that was to note where my car orginally came from. LOL! I doubt there is such a rule to say that the engine has to be replaced every 30k miles, less 30k km!

Suberman on Wed February 02, 2011 7:52 AM User is offline

Quote
Originally posted by: mk378
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.

I physically checked the compressor the other day when i pressed the button, it hooked up and was spinning. Everything under the hood looks fine. But no cold air.

As i've replied to Nick, i doubt it's the TXV? Because the compressor has been replaced last month and the problem was there before as well.

I was saying in my previous post, for the past week it was fine, only happened today again. And this time even though it was only parked for over 5 hours!

Thanks for all the help mate! Appreciate your thoughts.

How do i use the gauges to test it? What gauges and how do i go about doing it?

NickD on Wed February 02, 2011 9:58 AM User is offline

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.

JJM on Sat February 05, 2011 2:00 AM User is offline

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...

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com



NickD on Sat February 05, 2011 5:59 AM User is offline

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.

Suberman on Tue March 01, 2011 3:51 AM User is offline

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?

mk378 on Tue March 01, 2011 9:51 AM User is offline

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

Suberman on Mon May 09, 2011 5:20 AM User is offline

Quote
Originally posted by: mk378
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.

Hi mk378,

I've just sent the car for a complete refrigerant recharge and it still does it. So i think that's not it then. So i guess i'll have to hook it up to a set of gauges if i'm going to narrow down the problem.

I noticed something though. It seems to go in cycles. The delay happens quite regularly for a week or so then goes off and no problems at all for another 2 weeks or so then the cycle repeats.

Is hooking up the gauges and diagnosing the problem as easy as it sounds? I do not have any mechanical background at all. Any links to a step by step process?

Many thanks fella!

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