348 A/C 30A Fuse

One more stupid newbie question as I prep for my projects over the long holiday weekend:

In FerrariForum, there is a reference to a 30A A/C fuse under the "right side" felt covers in the trunk. Before I start tearing out the felt, is this fuse really in a 1990 (Feb '90 build) 348? My fuses, relays, and ABS bottle are all on the left-hand side under an easily accesible cover. Why would Ferrari put an in-line 30A fuse buried under the felt on the other side of the car?

http://www.ferrariforum.net/tech/view.php?id=14

My compresor doesn't even kick on -- let alone cool the car -- so I want to check electrical stuff before going any deeper.

Can somebody confirm location of the blade fuse suggested in F-Forum?

Huge thanks in advance,
Daniel

 

Daniel,

My 30A fuse is there in my '90, just like in the picture except it is clipped to one of the two green relays (the one toward the front of the car). When I took my felt liner out 4 years ago to recharge the AC, I never put it back in - all the mechanical stuff looked better than the liner.

Bob

p.s. I'll be ready to run the Bermuda rally the week of the 4th; don't know which day yet.

 

Mine is in the same spot. I have a 91

 

The "hidden fuse" isn't mentioned in the Owner's Handbook, but it's there, under the trunk liner. Stupid location. It was melted in my 348 when I got it.

 

Although I didn't physically look for the fuse, I did find it in the WSM. It's shown in the wiring schematic on page L31 (Top R/H) as fuse 69 "Air conditioning system protection fuse 30A".

Seems like a pretty important fuse to have omitted entirely from the main specifications. Crazy Italians.


-Daniel

 

It is definately there. I just got done doing this fix to my car yesterday. It works great. My A/C went out on me last week and I thought I would have to replace the climate control unit. You can get the larger fuses at Pep boys.

 

A bad fuse is one possible cause. . . another (as I discovered recently) is that the compressor will not kick on if their is insufficent pressure in the AC system. Had my recharged recently during my 30K service, but a bad connector prevented enought "freon" from getting into the system. As a result, the compressor would not kick on. Once we got the pressure right the system works great, cold enought to produce ICE on a hot day!

Good Luck

 

Well, I can safely say the 30A fuse wasn't the problem. Indeed, that blade fuse gets quite hot, but it was still intact and the holder was solid. But, since I'd already spent $16 on a nice in-line unit, I just couldn't prevent myself from performing a little surgery on the car. New fuse in place, still nothing.

I also started swapping relays on the left-side board, thinking maybe one of those had gone bad. The dipped beam and high beam (if I remember correctly) are the same relays -- so I used those as guinea pigs. Still no cold air for me! BTW: I was running on full LO temp with highest fan speed.

Lastly, I'm a total newbie when it comes to AC systems. I noticed there wasn't even the slightest chill on the freon lines running to the dryer. Should there have been anything? Let me guess: no compressor -> no cold freon -> nothing gets to the dryer.

The next step will obviously be something more intrusive. I'll either pull the compressor, or dump a bunch of freon into it and see if something kicks over. Ozone level be damned.... I want cold air.

-Daniel

 

Daniel

A/C systems are very simple. What you need to do is make sure your compressor is actually engaged and making pressure. When you turn on the A/C does your compressor clutch lock to the center hub and is the center hub spinning with the outer clutch pulley?

If it is, you will need to get a set of R-12 A/C gauges and check your pressures at the high and low side adapters.

At 2000rpm your low side pressure should be approx. 20-40lbs
Your high side pressure should be 180-210.

The high side can be higher depending on the ambient temp and the amount of air passing over the condensor. The low side is not as dependent on ambient temp.

As far as the temp of the hoses and pipes on your A/C. The discharge line from the compressor to the condensor will be very hot. The line from the condensor to the evaporator and the expansion valve will be only slightly cooler.(still very hot) The larger hose from the evaporator back to the compressor will be cool. Not cold. The freon takes the heat out of the car and passes it to the outside air via the differing pressure between the back of the expansion valve and the condensor. It is simply a heat exchange system.

If your compressor is not engaging via the clutch, check and make sure your electrical connection at the clutch is good and that there is battery voltage at the connector with the A/C on and the engine running. If not, you have a control problem that could include fuses, switches, pressure sensors. and thermistors If it has battery voltage, and is not engaging, you have a mechanical or electrical problem with the compressor clutch. If the compressor and clutch are spinning together, you have a problem with the freon flow. It could just be the system is very low on freon.

If you have a problem that will require opening the system, I recommend retro-fitting the system to R-134. R-12 is getting very expensive (about $50.00 per lb.) and more and more stores will not sell you R-12 unless you have a A/C certification card.

If you need more info, feel free to PM or email me

By the way, if you don't have any A/C gauges, you might check with Auto Zone. They rent tools and stuff here in Texas, and they have A/C gauges.

 

I also have A/C problems with my 348 - in that I get nothing.

If I hard wire +12V to the compressor should I see the clutch cut in ?

Just trying to work back from the source of the problem

My system has been re-charged, and is pressurised


I will also check out the 30A fuse - didn't know it was located where it was.

thanks for the pics.

 

Steven -

Thank you for the excellent write-up. I'll start poking around the compressor more seriously this evening. A colleague at work has a set of AC gauges, so I'll ask him to come lend a hand. As an interesting side note, I discovered about 20 pounds of left-over/disabled wiring behind the felt (old stereo systems, alarms, hard-wired radar detectors, etc).

Bob: did you say you've been running the car without all that felt covering the the trunk? I'm inclined to do the same thing -- everything is very accessible now, and it probably didn't contribute to much insulation anyway.


Thanks,
Daniel

-Daniel

 

Hi Daniel,

First off - I'm a 328 guy, so can't offer you specific advice on the 348 cars. But as stated above, A/C systems aren't necessarily that complicated. Typically the filter-dryer has a "pressure switch" that prevents energizing the magnetic clutch if system pressure is too low (basically prevents running compressor no-load & burning up). You can usually get an idea of system charge by looking into "sight glass" (usually in-line or on top of dryer) when system functioning; no bubbles = full charge or full discharge. Bubbles (assuming original freon) indicate partial charge. Since you system *isn't* running, you can (briefly) depress either schraeder valve and if refrigerant blows out at high pressure...my friend your system is charged. Wear goggles & gloves and don't stand directly above when trying this.

Another poster mentioned converting to R-134a above. This is a more complicated process than simple recharge; must replace dryer (never a bad idea) and flush entire system to remove the 525v oil that circulates with freon & blends. To do this properly you'll need to remove the expansion valve and flush pre/post condensor & evaporator. Some folks also reccomend replacing the o-rings when changing refrigerants.

Having said this, I've had pretty good results with one of the R-12 "blend" refrigerants - HC-12 - which is legal (i.e. no license required) & can be purchased for about $6/6oz can. Don't need to change out parts or flush system. Fox Tools in Memphis sells for $69/case. Now you will hear all kinds of stories about "blends" but another FC member (who told me about) has 7 years excellent experience in his cars.

Would reccomend "Haynes Automotive Heating and Air Conditioning Manual" ISBN 1850104808 which you local auto parts store likely stocks as good primer to get started. Also look over my tech article on the other board about AC repair (for 328, but general principles similar) or send me a PM & I'll burn you a CD. . For the 328 at least, many parts were "off-the-shelf" and not necessaily specific Ferrari brand.

Carl

 

Carl -

Thanks for your post! This is exactly why I love F-Chat!!

The sight glass in the dryer is about the size of a pinhead. Not really, but it's quite small. No matter how carefully I positioned my head or a flashlight, I couldn't see anything going on throught that little window. It just looks like a black hole of nothingness.

Schraeder Valve? Can anybody give an idea of where on the 348 I'd find it? Yes, I'll wear goggles and a full chemical suit. I'm starting to wonder if the system is dry, and that's why nothing is kicking over.

-Daniel
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Hi again Daniel,

Schraeder valves are the little protrusions that have little black screw-on caps. Great diagram above, expect (if like 328) fittings that attach to compressor itself have schraeder valves (sortof will resemble aluminum versions of standard (not presta) bicycle tube valves.

Suspect since your system is not cycling (no pun intended) the sight glass trick won't help you much. Failing all this, you can crack fitting at dryer open slightly and watch for refrigerant spill.

Carl

 

Daniel,

these 2 valves are located on the right hand side of the car looking from the front.

There are 2 pipes, just right & below the blower unit, each with what looks like a tyre valve cap. If you remove these you can press in the valve stem and should hear a hiss.

MIie was rather feeble, but I don't know if that's because I can't get the compressor going

We seem to be tracing the same fault at present.

My next steps are:

Disconnect wire from top of compressor and hard wire +12v. If the clutch cuts in then the compressor is OK.

After that, I need to fnd out how to check if the high & low pressure regulators are 'closed'. Don't know where they are yet, or what connections to check but will let you know if I find out.



John

 

Daniel

Have you solved your A/C problem?

 

Steve,

I appear to be tracking the same fault as Daniel.

I am beginning to suspect the A/C control unit.

Checked for power to the HI/LOW pressure regulator located on the drier last night.

Nothing there. (I am presuming I should see 12v somewhere).


John

 

No resolution yet. Mrs. Jack Russell Racing and I went for a holiday to the Virginia mountains. Despite the nice twisty roads, we opted for the big Bimmer instead of the sweaty 348. I'm planning to get into the garage tomorrow morning and do some more diagnostics.

-Daniel

 

Daniel

You have a PM

 

John

If you are not getting battery voltage at the high/low pressure switch, you have a control circuit problem. Make sure all of your fuses are good, particularly the one mentioned earlier by the relay block.

If you blower motor functions normally you can elliminate a large block of wiring circuits and focus on the compressor supply circuit and the ground circuit.

You will need the wiring diagrams to trace the current flow. If your compressor button lights up when you press it, that is a good place to start. If not, start from the fuse.

Hope this helps. If I had a wiring diagram I could be more specific.

 

Steve,

stripped down a/c panel - cleaned DIN connector and resoldered connections for good measure.

+12v now at hi/low pressure regulator but still no compressor cutting in.

By-passed the low pressure connector (black wires) and bingo, compressor now operates.

No cold air, no pressure from the tyre type valves.

So, next step is a pressure test at a local A/C specialist although they did suggest running the system with some dyed gas/fluid as minor pin holes leaks may not show on a pressure test.


Cheers


john

 

OK, I finally got out to the garage to hit those Schraeder valves. What kind of pressure should I expect? The pressure/volume was nothing like a bicycle or car tire... it was rather weak... like a light hissing noise (at most).

A buddy at the office (BORKAP) has some gauges, so I can hook those up next. But am I onto something just by the pathetic little hiss from that valve? BTW, I have also learned from PO that system has been converted to R134a -- so at least I'm not totally up a creek.

Advice?


-Daniel

 

Daniel

A fully charged R-134 system should have 30-40psi low side pressure, and 200-220 high side, depending on ambient temp, at 2000-3000rpm.

When just hooking into the system without the compressor turning, or even the engine on, the static pressures will probably be about 100psi. Both gauges, high and low, will read the same. The system equalizes when the compressor stops turning.

So, you should get more than a pathetic little hiss when you depress the schrader valve. It should give you a pretty good shot of R-134 from either valve.

I would be willing to bet your entire problem is due to low refrigerent.

You can recharge the sytem with R-134 and see if it works. I am not sure the capacity of the 348 system, but a pound and a half should be plentyto start with. There should be a yellow and black label on the engine cover that has the exact spec. If you can, evacuate the system with a vacume pump for at least 30 minutes to draw any moisture out of the system.

Ideally, you need a leak detector to check the entire system for leaks. You can use dye, but I prefer to not use it as there are some manufacturers that are refusing warranty coverage for any A/C systems exhibiting dye usage. That wouldn't apply to you, but obviously the manufacturers are having some issues with it.

The most common point for leaks on R-12 systems (which your is, even though it has been converted) is schrader valves, (especially if the seal caps are missing), expansion valve, and compressor shaft seal. I see some leakage at the condensor fittings due to damage from line shake, and impact damage from road debris.

My advice, get a couple of cans of R-134, borrow some gauges and a vacume pump, evac the system. Let the system set for about 20 minutes and see if it holds the vacume. If it does, put about a pound and a half into the system and see if it cools. If it does, you have a small to medium refrigerent leak somewhere. If it doesn't cool, check your compressor and see if it is engaged, if it is, check your pressures. If the pressures are incorrect, you will have a problem either with the expansion valve, compressor, or some restriction somewhere in the system. If your pressures are within range, then you have an air flow problem in the car.

If it cools well with the refrigerent installed, you can either inject some dye and drive the car for a while and try and find the telltale signs of leakage, or you can use a leak detector and try to pinpoint the leak. Remember, if you have a leak at the expansion valve or evaporator, the dye will not show unless you remove and disassemble the evaporator case to see the components. If you have a leak detector, you can insert the sniffer into the evaporator drain tube and it will often find the leaking refrigerent as the R-134 is heavier than air and will drain out of the case at the lowest point.

Hope this helps

 

John

It sound like you are low on refrigerent also.

I have had no problems using dye. It is a good way to find leaks. I mentioned the problem with dye just in case anyone has a concern with using in their systems. A really quality leak detector will find most leaks if the user is willing to spend the time and energy to properly use the detector. I admit quickly that I often use dye when I am not in such a dilligent mood.

Almost all A/C systems will lose refrigerent over time if they are not used. If the car has been sitting all winter, the compressor shaft seal will shrink and refrigerent will leak past. Even during the winter, you should run the compressor occasionally to keep the system working well and the refigerent oil circulated.

 

Steven -

WOW!! Terrific detailed advice. I'll give it a try tonight!! I've asked my colleague to bring his gagues into the office today, and I'll pick up a few pounds of R134a at noon.

Detailed answers like yours make me honored to be part of this community and prove the Rossa Membership is worth the price of admission.


Dreaming of chilly drives....

-Daniel