Does anyone have suggestions about keeping the A/C from freezing up in a 400i? This summer I had the system serviced and it blew 40 degree air. It did so for about 70 miles and froze. Having read the manual, I shut off the "snowflake" and thawed out the unit. After 9 hours of this the A/C quit cooling altogether. The A/C clutch had failed. So I bought the last clutch at Dennis McCann's . When the shop tried to remove the R-12 to install the clutch the R-12 had disappeared. It seems to have gone out past the shaft seal. I bought a kit from Rutlands, the shop installed it, pumped up the system and we were back to 40 degrees output. My wife took the car on a 1300 mile run and reported that the A/C had quit after an hour. I took it back to the shop thinking we'd lost the R-12 again. It was all still in the system and, of course, the system worked just fine in the shop. So I assume it had frozen up on her and that she hadn't read the manual. So, how does one set this outfit up to avoid the freezing? I already know what the manual says to do and suppose I am doing something wrong. Thanks, Greg
Greg I have the same issue only if at steady highway speed for 45+ minutes. I have the dual system and I try alternating between front and rear A/C units so one is always thawed out but this has limited success; I end up with both frozen. The most effective way to keep it running longest time is having the fan on high speed, both front and rear. You may have to wear a winter coat or turn on the heat when doing this! I had the clutch fail too. We thought the compressor locked up so I got a new York compressor and new clutch. Clutches are available through non-F sources (I made a post a couple of months ago). When I dismantlement the clutch/compressor the clutched was falling apart, balls falling out of bearing but the original Aspecia compressor turned free and had compression. Yesterday, I installed the new York and clutch; that is a lot of fun getting into a tight spot! Some say an under charge of Freon will cause icing; maybe slightly overfilling will prevent it. Withing the pressure ranges prescribed one might go for the high end. Let me know if you have any success. Ken
Thanks for your reply Ken. I have some business friends at Vintage Air and will ask about the under charge idea. The A/C shop first filled the system to the 3 pounds specified in the manual. The high and low pressure results were both high and the system surged. We ended up with 2.25 pounds in the system to get the rcommended pressures and eliminate the surge. Now that you mention it, the surge may have been caused by the failing clutch. I'll let you know what I learn from Vintage Air. Greg
Bingo!! Think of it as a mobile HVAC system (central air). When return air is starved (generally from dirty/clogged filters or return air blockage), the coils ice up resulting in no air flow either. I would ensure that the airway from the fan motors behind the front grille to the inside coil (coils in the dual air) are obstruction free, & that the inside coil/coils are not loaded with dust/dirt. Keeping the fan on high speed is a definate 'must', turning the temp. setting to a higher level & gradually working it down would be temporary work-arounds until you get things dismantled/cleaned. I'm real interested in the results of a low charge condition! 40 deg. air at the diffusers is a first to me!
Bruce The fans that push air thru the evaporator coils on the front (and certainly not the rear) are not the same fans that supply air for heating. The fans and air flow are completely separate. As far as I know the AC fans only circulate internal air. In the front the air inlet is near about where your knees are at the center of console. In the rear the intake is on the 'parcel' deck and outlets on the sides of the rear 'passengers'. This is why high outdoor humidity should dissipate as moisture inside the car decreases. Someone correct me if I am wrong. Ken p.s. I am talking about a Series II 400i. Earlier cars may be different since the AC layout was changed.
I'd have to look at one of my old manuals to be sure but would the system not have an evaporator temperature sensor possibly a capillary tube type,this is what I think the problem may be also double check the evaporator is not covered in dust and grime as this affects it's heat disapation ability.Most cars have some sort of evap temp sensors to prevent icing up,hope this helps.
Thanks for that clarification Ken, I stand corrected. Many auto manufacturers have 2 settings for A/C, 'normal' which allows outside air to flow through the system & 'max' which recirculates inside cabin air only (outside air shut off). It makes sense Ferrari only allows for recirculation only...with the exception of opening a vent somewhere. The principle still applies in regards to the quantity of air pulled through the coil (evap.) for heat transfer. This is why HVAC systems set the fan speed to 'high' when air conditioning...with the exception of variable fan speed units (which conjunctively varies the flow of freon from the outdoor condensor). The exception to this would be cold return air, which would freeze a coil big-time. B. I'm thinkin' that even if the sensor malfunctions, as long as the coil is free of obstruction...the coil won't freeze until return air gets pretty cold. The amount of air (& air temp.) pulled through the coil is critical on this whole 'icing up' thing, at least that's been my experience.
Below are some additional thoughts on this subject. The questions being answered are in the lower e-mail from me. Greg *Hi Greg, *While I can't claim to be an expert on Ferrari systems, external coil freeze up can only occur when the coil temperature is allowed to drop below thirty -two degrees, and there is water (humidity) from the air. I would start by checking the drain on the evaporator case. If the drain is partially plugged or not functioning as designed (or if it's poorly designed), the condensate will not be removed from the case, and the when the coil temperature goes below freezing, the condensate droplets on the coil fins will begin to crystalize (freeze). If the compressor continues to run (does not cycle off), the freezing will continue and spread until the entire coil becomes incased in ice. *A couple of things I would look at: *Is the evaporator case area well sealed and insulated so that it is taking in interior air? If the interior of the car is not well sealed or insulated and hot air surrounds the case, condensation will increase exponentially, and this means a big increase in water inside the case that may overwhelm the drain. *I don't know how the compressor is controlled in the Ferrari system, but a solution might be to install a thermostat to cycle the compressor and keep coil temperatures at the proper levels. *I can't see where low refrigerant charge will contribute to freeze up. If you are low on refrigerant, system performance will not be as good. This would normally not allow the coil temperature to pull down below thirty-two degrees. I would not continue to increase the charge. The numbers you list would actually be a little on the high side if the system is an TXV/receiver-drier based system depending on the engine RPM and test conditions where you took the readings. *Let me know what you find. * -----Original Message----- From: Gregory Frick [mailto:[email protected]] Sent: Sunday, November 13, 2011 11:22 AM Greg Frick from Inland Empire Drive Line here with a puzzle. Sometime when you have some time on your hands I'd appreciate your collective diagnosis of an A/C issue that seems common in Ferrari 400i. The system is prone to freeze up in 45 minutes to an hour when running at steady highway speeds. I have floated this issue on FerrariChat.com and find that others have the same problem. Here is the story of mine. The manual calls for 3.3 pounds of R-12 in cars with both front and rear A/C units. I had the system filled to that spec. This caused both the high and low pressure readings to run high and made the system surge. To get the high and low pressures within spec we ended up with 2.25 pounds of R-12 in it and blowing 40 degrees inside the car. This 2.2 pounds is what the manual recommends for cars with front A/C only. * The compressor is a York unit from an Italian York licensee. On a run to Minnesota the A/C would freeze up every hour or so. After 9 hours of freezing and thawing it quit altogether. When we got home I discovered that the clutch had failed and so ordered a new one, the very last such new one in the US. Back to the shop for installation and we found that the R-12 had escaped. I ordered a shaft seal repair kit and got that fixed. The system was again filled with 2.25 pounds and we were back to 40 degree output. Carolyn took the car to Minnesota again and it froze up in an hour again. She never did get it to work after that. Back at the shop Friday we found all 2.25 pounds still in the system and still blowing 40 degrees. It has been suggested that the freezing comes from low freon. It has dawned on me that the surge we encountered might have been the clutch going away. If we must go to 3.3 pounds can we ignore the high low pressures? As I remember the low is 30 and the high 250 with the 2.25 pound charge. The owner's manual talks specifically about the system freezing and how to deal with it. So if you come back with "That is the nature of 1984 systems" it won't be a surprise. I'll appreciate any suggestions you may have time to offer. Greg
Greg I think it is the Inland person that started out "Hi Greg". In any case some comments on his response: - Yes a poor evaporator drain will cause what we are seeing. I check both my back and front drains and they were quite clear. - The 400 AC front evaporator is completely inside the passenger compartment. So what are we insulating from. It is not exposed to outside air. Where will the excess condensation come from but the cabin air which is what you are trying to cool and dehumidify. The rear Evaporator is between the rear seats and an panel at back of trunk. There should be no air flow around it but it is in stagnant air separate from the cabin. Both evaporators freeze. -Prior to freezing the air flow through the front grill is very high so there are no restrictions to air flow. Air flow drops off as it begins to freeze. - as far as I know the compressor only cycles on high and low pressure at the dryer. I have never figured out what the snow flake switch does but I have tried full cw and full ccw and the result is the same. I replace the rear capillary a few years ago and no change. - as for charge pressure; this is my profession, chemical engineer. The Freon has a vapor pressure curve the higher the pressure the higher the boiling point. At lower suction pressure to the compressor the Freon will evaporate at a lower pressure. Raise the pressure and it will evaporate at a higher temperature. Obviously there is a minimum and a maximum range for the charge. Too much can really do damage in a hurry. Ken
Actually, I am the Inland person. I guess I should have edited that out. As my friend in the A/C business says, he knows nothing about the Ferrari system and offering some generic suggestions. As a Chemical Engineer you have probably forgotten more about the behavior of Freon than all the rest of know in sum. I am afraid that the freezing up is just the nature of the beast. I think this because the 400s all seem to do it and because there is a specific reference to freezing and how to cope with it in the owners manual. Probably it is just part of being a 1984 design. Still... Greg
Maybe where the hi & lo pressure lines go thru the firewall?? But w/both evap's freezing, that probably can be ruled out. It's got to be the thermostat,...I'm wondering if that might be the problem.
There is an easy fix to this. My BMW 745i did the same thing. There is a thermocoupler switch that cycles the compressor off for short periods of time when the evaporator temp gets low enough to freeze. On my bimmer that switch is a giant pain in the arse to get to, being buried under the blower system... so I just installed an aftermarket one in series with the wire going to the compressor clutch. You will have to remove enough trim (I know exactly how much for the bimmer, have no idea on the Ferrari) to get to either the inlet tube to the evaporator (larger of the two pipes) or to part of the evaporator itself. If you can get to the tube, you can remove the tar tape type insulation, and hose clamp the thermocoupler to the tube, then replace the insulation (may have to get some more if it has lost its "sticky" but 3M strip caulk works fine. You can even get an adjustable switch and fine tune it. My ac has not frozen up in 8 years. Have done this fix on multiple vehicles.
I have dealt with this by installing a toggle switch at the bottom of the dashboard, making me a human thermocoupler I suppose.
Yeah, I did that for a while in the first bimmer that did this. Got tired of it, and put in a thermocoupler. Actually, on my 745i, I put an adjustable one where my old fader control was, seeing as I had put in an aftermarket radio with built in fader controls. That way, when I am using defrost, I can turn it all the way down and just use the bare minimun compressor use needed.
I just replaced clutch, compressor and dryer/filter in our 400i GT. Clutch was slipping, but wasn't sure if it was compressor or clutch. New is York/Aspera Part No. 106607, superceded by 115776. Drove it home from shop (2 hrs Spartanburg to Aiken, SC) in 90°F and worked flawlessly on R134. FOR SALE: Used York/Aspera A/C compressor (needs shaft gasket), Part #115776, and Dryer/Filter Part #129101 (supersedes 62433100/A). $500 OBO.
OH, forgot: This A/C compressor fits Ferraris from early 70s to around 1989. 365, 308, 328, 400, 400i, 208.
Is it a 10cc compressor? I believe the dual AC 400i's have a bigger 10cc compressor and the single AC 400i's and the V8 cars had a smaller 7cc unit. Al
Ok it's a bit late, but as I am replacing the expansion valve of my AC, I've noticed that the probe and sensors are not installed "by the book". I am no AC technician, but the expansion valve instructions explicitly requires that the expansion valve sensor should sit on top of the tube, not under as was the case in my car... There is a risk to seize the compressor. A few more details are provided in the other guys websites (http://forums.pelicanparts.com/porsche-911-technical-forum/759863-ac-expansion-valve-tape.html#post7539248). But the idea is that the oil that flows in the tubes somehow isolate the sensor from the freon, and prevent the expansion valve from detecting that the freon is in its liquid form and may seize the compressor. It does not cost much to rotate the sensor and maybe that replacing the $12 expansion valve would be a good idea. Note that the gooey mess around the valve is "cork tape", and should not be discarded (as I did...). Image Unavailable, Please Login The snow flake switch is supposed to toggle the compressor on/off, but I presume the probe that is inserted in the evaporator fins should also be isolated (with cork tape?), as the hot air from the transmission is probably making the probe totally useless.
I redid my Porsche ac a while back. Buy some prestite cork tape from autozone to insulate your expansion valve. https://www.autozone.com/miscellaneous-non-automotive/tape/santech-prestite-tape/158980_0
The blue snowflake switch should not need insulation. The capillary has virtually no volume relative to the bulb which is being heated and cooled at the expansion valve. Also note that the expansion valve and switch assembly is a part common with Jaguar, maybe not the snowflake but the rest! Ken
