Air Conditioner blows fuses on a 550 Maranello

Has anyone had the air conditioner blow fuses after being on for a few miles. When driving on the freeway about 20 to 30 miles the radio and A/C go off blowing the 20 amp fuse, but if I leave the A/C off the radio stays on and the fuse does not burn out, so I asume it must be in the A/C system. Does anyone know what else is on this circuit. I am hoping someone may of allready solved this problem.

Chuck

 

Chuck,

I had this problem last summer during a heat wave. I changed the fuse a couple of times but it would always blow after a few miles.
It turned out the electromagnetic clutch in the A/C compressor's pulley was shorting the fuse. Upon inspection, the compressor was also diagnosed as shot as it was bathing in its own oil.
The whole compressor was replaced as a result....

Stefano

 

Chuck,

Can you measure the current draw either at the fuse or at the clutch?
At the fuse you can remove fuse and insert a current meter inline, at the clutch there is a plug in connector and you can measure the current here. Look for steady current (can't remember is it 2A?).

Also swop the a/c relay with say the main beam lights relay to see if the relay is at fault (make sure same Bosch number) , but if this is faulty is usually switches the a/c off not causes a high current. But it could be cycling the clutch on and off rapidly.

I had my compressor rebuilt for a few hundred bucks, they will also check the clutch for you.

Keep us updated,
Ron

 

Thanks Guys. I think Maranello72 has hit it because there is an oil leak below the Comperssor that was not there before it started blowing fuses. as soon as I can get it on the lift and get the under tray off I will pull the compressor.

Chuck

 

Thanks for posting. I'll bank this one for when mine starts blowing its fuse.

 

Safest to do as advised above and check the current draw at the clutch first. Oil can sometimes come from the cam seals or the valve cover gasket both higher up just about on top of the compressor. If you have a halogen sniffer handy that can yield more clues. If the compressor really is leaking oil then it needs to be rebuilt. But a creful diagnosis will save you from more work than you have to do.

 

If you find that the compressor has been leaking oil out the front seal, it would be wise to next have a look at the alternator which is directly underneath the compressor and see what kind of shape it's in. If it's gummed up with oil from the compressor, it should be removed, cleaned out (especially the diode bridge at the rear) and load tested.

BTW, these guys: Aftermarket Compressors For Ferrari Automobiles (AKA Polar Bear, Inc) do a nice job of rebuilding/exchanging our compressors for a fair price.

 

Oil does not compress too readily so no wonder it was blowing fuses.

 

When I took the car for the yearly service last May, I noticed a couple of oil drops on the under tray directly below the compressor and told the workshop. They checked the pressure in the AC system, it was fine, so they told me not to worry about it.
In July the compressor failed....

Stefano

 

I dont think the loss of a few oil drops would cause the fuses to blow, advise check current as recommended above,
Ron

 

Thanks everyone,

I got the air filter off yesterday so I could see what was in there and found the right cam cover or camshaft seal leaking and soaking the compressor and alternator. I will have to see which is leaking and check the wiring and freon after I get the oil mess cleaned up. I had to take the undertray off to get the air filter out of the way because there is one nut under the box you can't get with the undertray in place.

Chuck

 

I Finally found the problem and have it repaired. The a/c clutch coil was covered with oil and it must of damaged the coil insulation causing the coil to heat up after about 30 to 40 minutes blowing the fuse rather than being a direct short and blowing it rite away. I finally hooked a direct wire from the battery to a 20 amp fuse and then to the coil positive wire after disconnecting it from the harness. let it set for about 30 minutes while it got very hot and ended up blowing the fuse. Ferrari does not service the coil separate from the compressor assembly ($4100.00) so I went to one of our local air conditioning shops and started matching until we found one from a Cadillac Catera that was the same except it has two wires while the Ferrari one has only one wire and uses the coil mounting to the bracket for grounding, the other wire goes to the relay in the passenger floor. The Catera coil also did not have the Diode in the Positive wire so I had to transfer the one from the Ferrari coil to the Catera coil and add a ground wire to the Negative wire and connect it to a ground on the bracket. This can all be done without removing the compressor from the car that would require recharging the system with freon and oil. I am now getting a 25 Deg F temp drop from the OAT to the air coming out of the center ducts and it will stay on as long as necessary without blowing the fuse.

Chuck

 

Chuck, thanks for updating the thread and congrats on solving the problem!

 

Chuck- Amazing how minor leaks cascade on you. Glad you found the problem.

 

Hey Guys,
I just had this exact same issue happen to me today Ive always had great AC in my car without any issues ever until today. I was driving the car a little harder than usual and hit a pot hole than immediately the radio & AC shut off. I already tried replacing the fuse 2x and blows out after about 10 min. If I do not turn AC on radio works fine until I turn AC on. Sounds like the same issue as yours but do you guys think that the pot hole could have caused something to happen? It didn't bottom out it just hit hard. Any advice would be greatly appreciated

 

"DPA", I think it would be very coincidental if the bump didn't cause the problem.

The circuit is quite simple. Fuse 22 power is fed to the HVAC relay in the footwell. Power comes out of the relay panel on pin 3 of plug "E" on a green/black wire. This goes to the Right Hand Engine Connector (which I believe is behind the right hand kick panel?) and then to the compressor clutch in the engine bay. The bump may have exacerbated an existing fault in an aging electrical connector, but apart from the connector on the compressor clutch, the connectors seem to be in areas not affected by heat and contaminants. I would focus on the wiring in the engine comparment. If nothing evident, I would have the compressor clutch replaced. Is the 550 compressor a Sanden? I believe you can buy clutches separately on eBay relatively cheaply.

Here's the wiring diagram:

Ferrari 550 HVAC Wiring Diagram

It's a complicated diagram (overall), but find fuse 22, then track the red wiring to relay "M", then follow the wiring to relay panel plug "E". There is a small graphic above the fuse panel which shows where this plug is physically located on your car.

Maybe you could try disconnecting the plug at the compressor, then turning on the AC and going for a drive. If the fuse still blows, then it would be a short in the wiring and not a compressor clutch problem. Having said that, I don't know how the system reacts to having the compressor electrically disconnected. It might simply disable the compressor relay, so no current will flow to the short circuit (so no blown fuse).

Experts?

 

Hi

I had the same problem.
Change the Compressor and everything is fine.

Daniel

 

appreciate all the info!! Going to dig into it this weekend, looks like the compressor seems to be the culprit in most cases. After a proper diagnosis I should hopefully know. will keep you guys updated

 

Hopefully be that simple, tnxs

 

Have an Air Conditioner shop check the A/C clutch coil for excessive amperage draw, any good A/C shop should be able to check it. And replace only the Clutch Coil by buying a Coil for a late 90s Cadillac Catera and transferring the Diode that is attached to your old Coil on to the new Coil. The Compressor its self doesn't normally need replacement if it turns freely with the clutch disengaged. But Ferrari won't just sell you just a Clutch Coil, They will only sell you a complete Compressor and clutch assembly, ( about $4,000.00) The Coil alone is only a couple hundred Dollars, and the Compressor doesn't even need to be removed from the engine or the system need to be recharged. Mine was blowing the fuse after driving 5 or 6 miles and that was all it needed. About $4,000.00 Saved and still working fine after 6 years.

Chuck

 

I had an A/C shop replace a coil for far less that that. Common issue with those.

 

Amazing! im in Los Angeles. Can anyone recommend a good AC shop out here that won't gouge you when they see a Ferrari pulling in If not I can probably have a local mechanic just try and change the clutch coil. Is 90s Cadillac Catera the best way to go?

 

We just went thru the shelf until we found one that fit and it happened to be from the Cadillac Catera. The Catera coil we used had two wires, one for power and the other for ground, the Ferrari coil has only one wire with a Diode in it and is self grounding when mounted on the compressor so you transfer the wire from the Ferrari coil to the power wire and connect the other wire to ground, It doesn't make any difference which wire you choose as the power wire coming from your power source as long as the one coming from power has the Diode in it. Do not feed power to the coil without the Diode in the wire or you can damage the Computer.

Chuck

 

Hand them the compressor. They don't know or care what it is out of. If they really do you are doing business with disreputable people.

Getting the compressor out of a 550 isn't easy. Bring it to a Ferrari mechanic. No good reason in the world not to. In LA you have more choices in Ferrari mechanics than anywhere on planet earth. Some are good and some are bad. If you are getting screwed its your fault.

 

My A/C guy never even looks in a catalog. He looks the part over, walks in the back and comes out with a part. There are still people out there that good, you just need to find them.