ausubaru92 Posted October 15, 2004 Share Posted October 15, 2004 The aircon in my 92 dl wagon is pissin me off!!! When i switch it on it operates normally but only for a few minutes and then after that the air no longer blows cold. I have to switch it off then on again to make it to continue to cool the air. could this be a problem in the temp sensor in the heat exchanger? Link to comment Share on other sites More sharing options...
NorthWet Posted October 15, 2004 Share Posted October 15, 2004 How long has this been doing this? Did it work fine before and just start having this problem? Did you just make a change, like get a recharge? My vote goes for either the overtemp/pressure switch usually on the receiver/dryer (sightglass cylinder) or the pulse-counter on the compressor (which detects whether the compressor is turning so a siezed compressor doen't kill your drivebelt). Link to comment Share on other sites More sharing options...
ausubaru92 Posted October 15, 2004 Author Share Posted October 15, 2004 ive only had the car for about 6 months and i havent realy used the aircon in hot weather, i havent done any mods to the aircon. it seems to work ok when the outside air is cool,.. (like when im usin a/c to demist the windscreen at night) but it only runs for a few minutes when its a hot day Link to comment Share on other sites More sharing options...
NorthWet Posted October 15, 2004 Share Posted October 15, 2004 Take a look at the compressor next time you turn on the a/c. If it stays on for a couple seconds and then disengages, then the pulse-counter could be the fault. If it stays on for longer than a couple seconds it is prog something else. If it works ok on cool days but not on hot, I would suspect the overtemp/overpressure switch. It could either be a funky switch or a serious system condition... Been awhile since I did A/C for a living, but my guess is either under- or over-charged with refrigerant. An A/C place might be able to give you advice for free... just don't believe the first one you go to unless you know you can trust them. :-\ Do remember that the compressor normally cycles on/off but shill should blow cold. And, oh... with the compressor on for a few seconds check the siteglass for bubbles. Some are OK/normal, froth is not. Link to comment Share on other sites More sharing options...
stngllhm Posted October 15, 2004 Share Posted October 15, 2004 the pulse-counter on the compressor (which detects whether the compressor is turning so a siezed compressor doen't kill your drivebelt). that has my vote Link to comment Share on other sites More sharing options...
ausubaru92 Posted October 18, 2004 Author Share Posted October 18, 2004 I checked the sight glass and it looks bubbly,.. it seems to cool effectively but only for a few minutes during warm weather. i used it the other nite when i drove in the rain and it cycled on and off every few minutes (noticeable by a decrease in power and a click in the left hand dash) im thinking along the lines of the temp sensor in the dash, is there a way to check it? Link to comment Share on other sites More sharing options...
NorthWet Posted October 18, 2004 Share Posted October 18, 2004 I checked the sight glass and it looks bubbly,.. it seems to cool effectively but only for a few minutes during warm weather. i used it the other nite when i drove in the rain and it cycled on and off every few minutes (noticeable by a decrease in power and a click in the left hand dash) im thinking along the lines of the temp sensor in the dash, is there a way to check it? What year/model is your car? *edit - Sorry just found info in orig post. Old-timer's disease... - end edit* Although I don't have my manuals at hand, I believe that at least with the pre-Legacy models Subaru did not have any temp sensor... It relies on the expansion valve alone. I have a thought, based on your "it operates normally but only for a few minutes and then after that the air no longer blows cold": What does the air temp feel like when you just are doing a "vent"-type function (bi-level??)? It is possible that you are getting hot heater air leaking in and mixing with A/C cooled air. As engine warms up, the heater air would get warmer. Our '82's heater has a water valve that stopped closing all of the way, causing this problem for us. And my Ford Aerostar (which has constant hot water flow to heater and just mixes air) has started not closing its heater-air flap - vent air blows warm now. Just something more to check. Oh, and make sure that nothing is clogging/blocking the fins on the A/C's "radiator" (between the grill and you coolant radiator). Link to comment Share on other sites More sharing options...
ausubaru92 Posted October 18, 2004 Author Share Posted October 18, 2004 ive ruled out the vent cos i can change the air temp between ambient temp and realy hot. Is the expansion valve the device inside the dash which clicks as the air-con cycles on and off every few minutes. cos when it isnt working,.. it dosent click (except for when u turn it first on,.. it cools the air, clicks again and then thats it) until you switch the air-con off then on again then it will cycle once more. It only does this during warm days Link to comment Share on other sites More sharing options...
NorthWet Posted October 18, 2004 Share Posted October 18, 2004 ...Is the expansion valve the device inside the dash which clicks as the air-con cycles on and off every few minutes. cos when it isnt working,.. it dosent click (except for when u turn it first on,.. it cools the air, clicks again and then thats it) until you switch the air-con off then on again then it will cycle once more... Disclaimer: Last time I worked professionally with A/C was 1977... Do NOT take what I say as absolute fact. If it sounds wrong then get another opinion, please. Expansion valves shouldn't click... they normally have just a bulb-type temperature sensor and tubing connected to a diaphram, which controls the orifice that the refrigerant passes through. Usually, the only clicking from an A/C system should be the clutch on the compressor cycling on and off. If you are hearing clicking noises from the dash that aren't just transconducted noise from the compressor clutch then I have no idea what it is. (i.e. - If the noise really is from the dash then I am stumped.) At this point, given that you say the compressor is cycling (as opposed to stopping and never coming back on), my guess is that the A/C system is just not up to the task. Possibly low refrigerant charge, obstructed condenser ("radiator"), or bad expansion valve. Maybe someone on USMB with more (and more-current!!! lol) A/C knowledge can offer some insight? Link to comment Share on other sites More sharing options...
ausubaru92 Posted October 19, 2004 Author Share Posted October 19, 2004 What causes the compressor to cycle on and off every few minutes??? To clear any possiable confusion,... My air-con cycles (on then off every few minules) as normal when the weather is cool. (i can tell it is cycling cos when the compressor comes in i feel the engine load, accompanied by a click) BUT when the weather is warm, the compressor comes on only once and i can only make it continue by constantly switching off and on the A/C button. I hope this makes sense:-\ Link to comment Share on other sites More sharing options...
NorthWet Posted October 19, 2004 Share Posted October 19, 2004 What causes the compressor to cycle on and off every few minutes??? To clear any possiable confusion,... My air-con cycles (on then off every few minules) as normal when the weather is cool. (i can tell it is cycling cos when the compressor comes in i feel the engine load, accompanied by a click) BUT when the weather is warm, the compressor comes on only once and i can only make it continue by constantly switching off and on the A/C button. I hope this makes sense:-\ It makes sense. IF I remember correctly (see previous disclaimer), the compressor cycling is controlled by system pressure. Once it reaches a certain pressure it cycles off until pressure drops below some low-pressure set point. If the expansion valve is wide full open, then it will keep the pressure below high set point longer, keeping the compressor on longer. You MAY be running against the high-pressure set point and/or the over-pressure point (may be one in the same on soobs, I honestly haven't looked into it). As I think that I typed previously, there should be a pressure switch on the receiver/dryer (canister with sightglass). You might try bypasing the switch next time the compressor stays off. WARNING: If there really is an over-pressure problem, bypassing this switch longer than necessary to see if the clutch activates could cause problems, including blowing out an over-pressure plug on the receiver/dryer which will spray all of your refridgerant into engine compartment and maybe your hands or face. My memory is really stretched by the preceeding. Again, if it does not sound right (except for the warning) please get a second opinion. Link to comment Share on other sites More sharing options...
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