993 aircon diagnosis required
Discussion
I think I may have a problem with my aircon but as this is the first time it's worked since I've had the car, it may be normal. If it is I'm disappointed.
I visited my local friendly garage (not Porsche specific), diagnosed a leaking condenser (hiss, quite easy), fixed it and refilled the system accordingly. All seemed to work, compressor, condenser fan, pressures were ok etc. According to the book, when the MAX AC button is pressed, maximum refrigeration is set, the fresh air flaps to the windscreen and footwells are closed (channeling all air to the centre and side vents) and the blower control automatically sets to speed 4 (flat out) but.........the flaps bit seems ok and briefly (couple of seconds) the blower reaches full thrape then dies away to about 1/4 throttle. The air being expelled is cool but not as cold as I would have expected. The blower appears to be ok (since it will happily blast away at speed 4 if the AC is switched off). I popped the pollen filters out and checked the evaporator temperature, which was certainly fridge cold so in the main the system must be doing the business. I have concluded that when the MAX AC button is pressed the blower only reaches full speed until the motor driven flaps are fully closed, then reduces speed.
Is it possible that the evaporator could be so clogged up that very little air passes through it? It certainly looks clean looking in from the pollen filter housing.
How much influence does the climate control unit have on this setting? (we are talking about a hot sunny day 30 degrees C, in a black car).
Suggestions gladly accepted.
I visited my local friendly garage (not Porsche specific), diagnosed a leaking condenser (hiss, quite easy), fixed it and refilled the system accordingly. All seemed to work, compressor, condenser fan, pressures were ok etc. According to the book, when the MAX AC button is pressed, maximum refrigeration is set, the fresh air flaps to the windscreen and footwells are closed (channeling all air to the centre and side vents) and the blower control automatically sets to speed 4 (flat out) but.........the flaps bit seems ok and briefly (couple of seconds) the blower reaches full thrape then dies away to about 1/4 throttle. The air being expelled is cool but not as cold as I would have expected. The blower appears to be ok (since it will happily blast away at speed 4 if the AC is switched off). I popped the pollen filters out and checked the evaporator temperature, which was certainly fridge cold so in the main the system must be doing the business. I have concluded that when the MAX AC button is pressed the blower only reaches full speed until the motor driven flaps are fully closed, then reduces speed.
Is it possible that the evaporator could be so clogged up that very little air passes through it? It certainly looks clean looking in from the pollen filter housing.
How much influence does the climate control unit have on this setting? (we are talking about a hot sunny day 30 degrees C, in a black car).
Suggestions gladly accepted.
Out at Le Mans last month in my silver 993, i had the aircon on full blast to keep the interior cool when stuck in a traffic jam when it was 35 degrees outside.
I guess with a black car and 30 degrees it might well be similar.
Got to say also that when i first got in the car, started the engine, and put the big snowflake on, the aircon speed went to about level 2 for about 30 seconds before then going to full blast.
Anyone else?
I guess with a black car and 30 degrees it might well be similar.
Got to say also that when i first got in the car, started the engine, and put the big snowflake on, the aircon speed went to about level 2 for about 30 seconds before then going to full blast.
Anyone else?
aceparts_com said:
While we're here, my air seems to blow harder out of the drivers side vents than the pasenger side!
Spooky, whilst delving in the fiddly dark spaces where the bonnet hinges go, I found a fat flexible pipe which looked like it originated from the footwell direction and headed for driver's side vent. The footwell end of mine wasn't located in it's hole so I just pressed it back in. Hadn't noticed in the car, just thought all 993 ventilation was rubbish!
Edited to say there is an identical set up on the passenger side but looks like a real b**** to get at.
>> Edited by gaity on Thursday 14th July 23:02
I think the pause for 10 secs or so before the fan reaches full speed is normal as mine does exactly the same. I've just had it regassed and it's better than it was, but not as good as say a modern Audi's A/C, but then I think Porsche always focussed more on the driving experience than the creature comforts (and we don't complain about that do we...)
If you hit the recirculate button, then it should make a bit the air come out a little colder. My experiences are based on Marbella heat, so should compare to what you're faced with...
If you hit the recirculate button, then it should make a bit the air come out a little colder. My experiences are based on Marbella heat, so should compare to what you're faced with...
evil jack said:
Mine packed up completely last month! Just in time for the heatwave... 
I was getting a frequent hissing sound coming from the left front footwell, so i'm guessing leaky condensor....
My leaky condenser was caused by the point of an overlong self tapper screw from the passenger side headlight cavity pressing down against the top flat tube of the condenser, eventually penetrating it. Nothing that a hacksaw and a spot of alloy welding couldn't put right (cheaper than a new condenser too).
verysideways said:
Of course to prevent problems like this, as far as possible, use the aircon regularly all year round (like 20 minutes at least once every couple of weeks).
VS
Agree with that, too. I've heard that if it goes unused for a while, all the seals dry up and refilling is a waste of time as the gas will all leak out until the seals are replaced - does that sound correct?
ocho said:
Of course to prevent problems like this, as far as possible, use the aircon regularly all year round (like 20 minutes at least once every couple of weeks).
VS
Agree with that, too. I've heard that if it goes unused for a while, all the seals dry up and refilling is a waste of time as the gas will all leak out until the seals are replaced - does that sound correct?
Yep, the gas contains an oil which lubricates all the seals. If the system isn't used the seals dry out and when you turn the system on the gas escapes.
It's definately a case of use it or lose it.
According to the workshop manual at 30 degrees ambient the cooling air should be between 6.5 and 10 degrees. At 35 it should be between 9 and 13.
Search on rennlist; there's a lot of AC experience there. Also check out www.porsche964.co.uk; there's a section on diagnosing the operation of the flaps.
Search on rennlist; there's a lot of AC experience there. Also check out www.porsche964.co.uk; there's a section on diagnosing the operation of the flaps.
Mine was a little less cool than I would have liked,,,earlier in the week I had my system checked, vacuumed and re-charged....
A big improvement, and seems fine a few days later....when it was 25-30 degrees outside, on recirculation and max blower the system got to a low of +3.5 degrees C at the vents.
I now need to see if the system maintains gas over the next few weeks, but seems like a well spent 60 notes up to now.
A big improvement, and seems fine a few days later....when it was 25-30 degrees outside, on recirculation and max blower the system got to a low of +3.5 degrees C at the vents.
I now need to see if the system maintains gas over the next few weeks, but seems like a well spent 60 notes up to now.
Spent a bit of time playing tonight and have arrived at a solution that works although not quite sure why. It seems that there may be a problem with the actual MAX AC button (or the processes it initiates). By unplugging the fresh-air flap servomotor (when in the open position), I can get full blower speed and beautiful fridge cold air into the cabin. If connected and left to it's own devices this flap closes and throttles the air through the evaporator when the MAX AC button is pressed, resulting in poor (read practically zero) air flow. Something isn't opening like it should somewhere. Clan gaity are going to Walton Hall this weekend so 2 hours 4-up driving will be a good test for my modified system if the weather forecast is to be believed!
Thanks for the link Phelix, the tips there can surely be applied to the 993 and I will be attempting to apply them next week to get the thing working like it was designed to.
Thanks for the link Phelix, the tips there can surely be applied to the 993 and I will be attempting to apply them next week to get the thing working like it was designed to.
Hello
I have a problem with my aircon on a 1995 993.
When the big blower button is pushed it shoots out cold air for about 10 secs and then pushes out warmer air at a much reduced rate.
The small blower button does not seem to do muct at all.
Can anyone tell me how these are supposed to work and whether I am using it correctly. Or if mine sounds knackered?
Thanks
Gavin
I have a problem with my aircon on a 1995 993.
When the big blower button is pushed it shoots out cold air for about 10 secs and then pushes out warmer air at a much reduced rate.
The small blower button does not seem to do muct at all.
Can anyone tell me how these are supposed to work and whether I am using it correctly. Or if mine sounds knackered?
Thanks
Gavin
When you put the small button on and the fan on '2' with the temperature turned to "as cold as possible" you should get a nice flow of chilled air from the vents.
The big snowflake is like putting max cold and max fan at the same time.
And no, you shouldn't be getting warm air out when you push the big snowflake.
The big snowflake is like putting max cold and max fan at the same time.
And no, you shouldn't be getting warm air out when you push the big snowflake.
The small snowflake button just turns on the compressor (assuming the temp knob is set low enough); fan speed and air distribution is as per the fan speed switch and the sliders on the CCU (Climate Control Unit).
The large snowflake button puts the fan on max, sets the temp to the minimum and closes the footwell and windscreen flaps.
When you're getting cold air from the system you should be able to see the AC compressor running when you open the engine lid and you should be able to hear/feel the AC condensor fan running as it pulls in at the bumper, through the condenser at the left front corner of the car and then out the downward-facing vent in front of the left front wheel.
If the compressor stops and the condenser fans stops when the AC should be running then you've obviously got a problem somewhere. Most common is too little refrigerant; if there isn't enough pressure in the system it won't run. Systems do tend to leak down over time, particularly with irregular use. You could also have a leak, perhaps at the condenser.
My advice would be to bring the car to an AC specialist (doesn't have to be a Porsche dealer) and have them test the high and low side pressures in the system. If they're not right then a re-gas is in order, probably with a leak detectant so that future troubleshooting is easier.
>> Edited by phelix on Monday 8th August 12:47
The large snowflake button puts the fan on max, sets the temp to the minimum and closes the footwell and windscreen flaps.
When you're getting cold air from the system you should be able to see the AC compressor running when you open the engine lid and you should be able to hear/feel the AC condensor fan running as it pulls in at the bumper, through the condenser at the left front corner of the car and then out the downward-facing vent in front of the left front wheel.
If the compressor stops and the condenser fans stops when the AC should be running then you've obviously got a problem somewhere. Most common is too little refrigerant; if there isn't enough pressure in the system it won't run. Systems do tend to leak down over time, particularly with irregular use. You could also have a leak, perhaps at the condenser.
My advice would be to bring the car to an AC specialist (doesn't have to be a Porsche dealer) and have them test the high and low side pressures in the system. If they're not right then a re-gas is in order, probably with a leak detectant so that future troubleshooting is easier.
>> Edited by phelix on Monday 8th August 12:47
If we assume the fridge bit is working for now, the symptoms sounds similar to mine, ie when the big snowflake is pressed, fan goes to max then dwindles to practically nothing after a few seconds. On mine I worked out that this is how long it takes for the fresh air flap to close. I stand to be corrected but I think another flap (bypass flap?) should be also be opening about now to allow interior air to flow through the evaporator (otherwise there is no air available for the fan to move hence reduced flow). Although I haven't had a chance to delve deeper yet, I believe the bypass flap is operated by a vacuum solenoid. I have managed to get mine working (functional) by unplugging the fresh air flap servo (in the open position). I guess this means no recirculating air function(?), but I'm cool for now!
I'll check the owner's manual but I don't believe the fresh air inlet should be shut off when the max AC buton is depressed; you should still be pulling in exterior air for cooling. Only when the recirc button is pressed should you be cooling interior air.
You say air flow drops. Can you tell if it's the fan speed dropping or if it's the supply or exit to the fan being blocked off? Net result may be the same but the cause may help indicate what's wrong.
You say air flow drops. Can you tell if it's the fan speed dropping or if it's the supply or exit to the fan being blocked off? Net result may be the same but the cause may help indicate what's wrong.
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