I thought I was finished thinking about my a/c problems for the season. but I just got an epiphany. my main problem was never a problem with my air conditioning system (ie compressor, dryer evap coil, and the rest). It's an air flow problem; hot air is entering into what should be a closed vented system. here's why I think I know this. was driving on a 75 degree day without the a/c (or fan on) and after the car warmed up, the air out of the vents was still around 10 degree hotter than OAT. (which is exactly what happens when the a/c is on). so the rise in temp has nothing to do with the a/c coming on or off or the dryer or evap coil or any of that stuff. It looks to me like I've got a leak/hole in some vent line probably near the radiator which gets pretty hot. I've got the vent and heat settings off and the vents are not really hot the way I would expect if the heater was on. so it seems to me that a hole in some air vent hose is the most logical explanation, or maybe if some of those hoses are supposed to be insulated, may my insulation is gone bad. any thoughts?
The foam around the evaporator is know to degrade and shoot out the vents. Thus, hot OA is bypassing the evap. and mixing with whatever gets through the evap. causing the mixed temp. to rise. I would say that as the car warms up, that OA entering the AC system does as well (remember, the radiator is under the hood = HOT air) making everything warmer. I've had a similar problem. Worked great last year, but as more and more foam shoots out the vents, it seems not to be as cool as last year.
you've got foam shooting out of your vents? what's the fix for that? I'm not clear of where or how this would work. but I've got the same problem even when the a/c is not operating, I'm not too familiar with a/c in general. but what's the mechanics/dynamics of the evaporator? do you mean that there is some kind of hole which lets hot air into the evaporator, or a hole where the evaporator connects to the air vent? sounds like you mean the latter.
Part 22 in the right diagram above is the evaporator. Part 10 is the fan. (right hand diagram) The fan blows air thru the evaporator. The evaporator is like the radiator --- the R12 goes thru it, absorbes the heat from the air and cools it the air (reverse of a car radiator). That cold air is blown into the car. The evaporator has foam around it to create a tight seal between the fans blowing the outside air and the evaporator. You want ALL air to go thru the evaporator. The foam deteriorates and allows warm air from the fan to bypass that evaporator and mix with air coming out of the evap (cold air) and warms it up. ------------------------ --- foam seal [ ] --> [ ] ---> [ ] --> [ ] ---> [ ] --> [ ] ---> --- foam seal ------------------------- FAN - Warm Air - Evap - Cold Air The evap. needs to be tightly sealed agains the walls on top and bottom (the foam). If it's not, the warm air will flow around it and mix with the cold air warming it up. One other thing - left hand diagram, if the flapper that your hand controls aren't set all the way forward (closing the flapper to Outside Air part #1) that air will mix in the box under the dash (part 22 ) again making things worse. I've noticed that as the car heats up, that air out of the vent gets pretty warm, regarless of the outside temperature. To fix the foam problem, you have to evacuate the system, remove the dash and take the evap coil out and put in new foam. It may be possible to squeeze some in around the evap. coil while it's somewhat together, but I've not tried that.
makes sense I guess, but how can the evaporator be the problem if I have it when the a/c is off. if it's off doesn't it mean that the a/c is not on line and nothing is passing through the evaporator and if so if it's not on, then that can't be the problem. what am I missing?
I missed something. Are you saying that the air gets warm coming into the car all the time after it warms up? I think every 308 has that problem. Mine does. After the car warms up and I'm moving, air just leaks in from under the dash area and warms up the foot well of the car. It really sucks. I'm pretty sure one of my vents is not closing properly and that is allowing hot air in. Remember, that radiator up front makes everything up front warm. The later 308's added venting to the hood. Also, the water pipes running through the middle of the car makes everything warmer in the cabin.
yes, I'm saying that with the a/c not operating at all. the vent temp starts out at ambient or a couple degrees warmer, and by the time the water and oil temp get around two thirds to the half way marki, the vent temp increases to around 8-10 degrees over ambient, that is with no a/c and no fan working. at the point I open the window to let in some noticably cooler air in than what is comming in from the vents. the vents are in the standard a/c positions: full down, while the water (center lever) is full up. My GT4 does have a vent in the front bonnet which I guess should vent some of the hot air out. from the above, it seems clear that the rise in vent temp is not related to the a/c system but is caused by hot air from the radiator somehow getting into the vent hoses. (previously I think I ruled out hot water by bypassing the hot water line that feeds into or is controlled by the hot water center lever) therefore it seems to me that I can't be having a problem with the evaporator, condensor or anything else which only operates when the a/c compressor is on. Or am I missing something?
Sean in my Gt4 Ive also got that pesky hot air problem coming from under the dashbut only on the drivers side(in my case the right hand side)That is also one of my biggest problems with trying to cool down my car.I think the hot air is stronger when my thermo fans cut in which leaves me to believe that I have a leak around the foot well under dash area.One other thing I have yet to try is to remove thefornt underbody pan which allows you access to the steering rack and try and insulate the hot water pipes with some wool insulation to reduce the heat transfer to the foot well area.Just one of those other things to do to add to the list
Rick this is the 1st problem you have to tackle in A/C theory.You have to be able to stop the hot air or heat load from coming in before you can try and cool the car down.If you want a big improvement I would suggest you try the vent mod that I spoke about earlier on regarding better vent flow distribution.It certainly made a huge difference to my car and you cant tell it has been done for concours/originalaty issues
If the vent levers are full forward then all vents should be closed off for outside air flow. If the temperature lever is full forward this is cold air (no hot water going to heater boxes). Mine does the same thing. Hot air leaks into the system (but not my AC vents, only the under dash area). In fact, warm air seems to come out from all over under the dash on the drivers side so I'm guessing hot air from the radiator is just leaking into my car. The more I think about it, the more it seems this started right about when I added sealing foam to the top of the radiator to help it cool better. I’m wondering if that hot air that used to flow over the top of the radiator and likely out over the windshield is now being forced around the sides more and into the heater fan inlets. Just because the fan is off does not mean air won’t go thru them. I really need to take the whole system apart and put in new seals, ducts, etc. The old system obviously has leaks. That being said, my AC cold air stays at the same temperature and does not warm up as you describe. It really sounds like you’ve got an air leak somewhere. Did you verify you’re vent levers control as they should? The passenger side on mine sticks and won’t close all the way. It will open, but if I want it closed I have to go under the hood and flip it over with a screwdriver. The little joint gets stuck on the friction lock and won’t move at all.
I had looked into the vent levers previously, One didn't seemed to be connected at all. I ended up manually closing them by fipping them closed. that didn't solve it. I'm still thinking a hole in the air vent hose somewhere. or maybe some insulation fell off surrounding a hose or something. There's no way this is how the car was designed or initially operated; so something's missing or broken with a hole; since it happens without a/c on the hot air from the front is obviously getting into the vent somewhere. It's not comming in from under the dash like the other guy's problem; it's from the air vents, which means I keep thinking a hole. I'll get it eventually.
It has been my experience with classic Ferrari A/Cs that the fan is the weak spot, not the compressor or evaporator.If there is a way to replace the OEM fan with one that puts out a greater volume of air, you would get a great improvement in the cooling . Has anyone ever done that?
Well, I think I have my air conditioning problem figured out, mostly that is. when last I posted, I determined that it wasn't really an air conditioning problem at all because even without the a/c on and on a cold day, the vent temp would get hot, around 90 degrees, in a cold day without the air conditioner! that meant I had either hot air from the radiator area entering the vent ducts, or it could have been hot water entering the system and my heating vent lever was inoperative. I previously tried to by-pass the heat knob, but that didn't help. my problem was that although I'd have cooling (at least 20 degrees from ambient) for awhile, once the temps (oil and water) would get close to normal operating temps, the vent temp would rise around 12 degress or so, leaving the vent temp maybe 5-10 less than ambient air. today I figured it out. Here's the clue; It was only the left top vent and the left mid vent which was blowing hot air. The right side was blowing cool ambient air even with the operating temps not far from midline: that obviously means I don't have a "hot water polluting the system" problem. I now know it's an air leak somewhere forward of where the mid level and top left vent split up. and here's the thing, once I closed the two left vents and also the middle vent, and just had the right vent opened; my duct temperature (with normal engine operating temps, and after running the car for 25 minutes) was a magnificant 42 degrees. And it was continually going down, the way it should since, as the cold air is recirculated it gets colder. At the end of the experiment it was down around 40 and still tending down. when I have the time I'll try to chase down the air leak, but now that I can maintain normal a/c temps even when the car is warm, I can live with the one vent, it just blows that much stronger. it's been a long journey; from switching from r12 to freeze 12 and then back to r 12, which helped; changing out the dryer, blowing out the system, changing out the expansion valve; all the by-passing of hoses. I'm not quite done, but I'm pretty close.
You know I put in a by pass valve for the hot water lines. On a cool day with no ac, the vent temp would be 120. with the bypass valve in it was 110. Are you telling me if I block off the heater vents at the heater water radiator, it will lower my vents temp. Seems to be easy to put a piece of card board in there instead of the filter. Let me know if i got this right, Kelly PS, I posted the drier numbers and expansion valve numbers about 4 or 5 years ago. You could see them if you did a search, or maybe verell and I are so old, not body could find them.
Hi Rick funny you should ressurect this thread again as I to was getting warm air in the cabin with the A/C off.I customised the air flow and I can tell you it is 100% better.First i removed the cover under the bonnet that exposes the fan and relevant ducting.I then removed the duct that feeds the top centre vent that was being fed from the A/C blower and capped off the centre vent.I then removed the ducts that supply the vents on either side of the foot wells and capped off the Y piece diverter on each side.I then got some new duct and a 65mm pvc Y joiner that I got from my local hardware store.I connected a piece of duct to one opening of the Y fiting and connected the other sides to the left and right lower vents.So now the A/C blower supplys the lower vents only.Whilst doing this I had noticed that one of the ducts that originally fed the right side lower vent was half off and hot air was getting in through there and mixing with my cold air.Ok already with this mod to the ducting it improved the A/C air distribution.I then went a little further and modified the lower vents inside the cabin.I got 2 80mm PVC 90 degree elbows and painted them matt black.I then removed the centre part of the lower vent and put the elbow in the vent and attached the centre part of the vent to the elbow opening.This took a little playing aroud at first as I had to heat up the elbow opening and expand it so that the inner vent piece would fit in.This may sound a bit confusing but I will take pics tomorrow and post them up.The end result if you can picture it is the air flows from either side of the cabin and is directed to your face/body and it looks pretty original obviously not concours but it doesnt take more that 5 mins to revert back to original.I will post pics tomorrow so you can see.This as I have stated improved the air distribution 100%
Another thing that I did previously that I didn't mention was that I hooked up a relay with a direct 12v fused power source to the blower fan motor.So the switch that turns the fan on activates the relay which powers up the motor.The result being the fan motor puts out a little more air than before probably 1/10 more and if you know how much air originally come out you would appreciate every extra bit of air flow.The only thing was that I couldnt retain the 3 speed function but it didn't worry me as I always had it on high speed anyway.If the air gets too cold you can just divert the flow using the vent flap.
Sean you are correct though I still have the vents either side of the centre vent connected to the left/right heater coils and they are connected to seperate individual fans which is still stock although in 3 years of ownership I've never needed to defrost the windscreen :.)My next project is to convert to a Sanden compressor, flush the system,replace drier and TX valve and go back to R12.Anyway here are the pics. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
