Hello all, Have a 1991 348TS with about 50,000 miles on it. The other day I went to start it and all the lights in the AC, heater control unit are dead. I checked the panel with the headlights on and the back lighting does work. Have never had any problems with this before. The unit does not respond to any commands at all. I do have an extra console panel that I am thinking about swapping in but I wanted some expert advice before I do this. Could it be the hidden ac fuse that has blown? I have never checked it and the ac does not work anyway. been told that it is the compressor. Is there a fuse that controls the operation of the panel. I have also had an intermittent high fan operation that comes and goes, with the console not showing this operation. I have found a tap to the passengers side center console causes this to beginning working normally again. Was going to take the center console apart and check connections, pins at the rear of the unit. any suggestions are welcome. Thanks
I had intermittent HVAC issues on my previous 348, a 90 ts. Here's my "hidden" fuse. https://www.ferrarichat.com/forum/threads/348-dead-hvac.453511/ Image Unavailable, Please Login
After fixing that... I still had some problems with the HVAC controller (which a slap to the side would "fix"). I replaced the unit with a later version. Everything was great after that.
Yes it was the hidden fuse, no burn marks, just blown, replaced and everything is back to normal. When I was in there I noticed 4 relays with fuses attached to the side of them, passenger side, on the wheel well area. I believe this is the anti skid control. There are 4 fuse slots but only 3 of them have fuses. Is this correct? Thanks again
The empty fuse slot is part of the brake diagnostic system. If I remember correctly its for resetting the abs warning lamp. At about 4 mins into the video he shows the empty slot.
It's a good idea to keep an eye on it. The fuses blow for a reason. Strangely, my system worked most of the time even with the horrific meltdown.
Instead of just replacing the fuse, it is advisable to replace the fuse holder (and fuse) by a bigger heavy duty one (like Maxi or ANL fuse). The new fuse should have the same Amp rating as the original one. You should also inspect the relay socket pin to which the hidden fuse provides power - make sure it is clean and has no signs of overheating/burning. These are weak points on the 348-s and have possibly caused fire on some. A few examples of heavy duty hidden fuses: Image Unavailable, Please Login Image Unavailable, Please Login
FYI if the problem with your A/C really is the compressor, and you have a Sanden brand unit, I found that I got an exact fit replacement that happens to also be used on Caterpillar vehicles for less than $150 last year. If you replace that, you do have to also replace the receiver/ dryer unit up by the right front fender. Sent from my VS990 using FerrariChat.com mobile app
I upgraded mine similar to what @m.stojanovic posted. Worked a treat for 7+ years while I owned the car.
Thanks for all the info guys, I will change the fuse to a more robust model. pnicholasen, what was the part number for the sanden brand unit, usually see them for much more. Thanks all.
It was a Sanden 4643 ear mount SD7H15 compressor. As I recall from my feeble memory I did have to switch the clutch assembly from the old compressor to the new one to get the correct grove type for the drive belt, although it may have been just the pulley part and the magnet was left in place. CAUTION: don't go ordering any compressor without pulling yours and checking brand and part # because yours could be different. Also of note: compressor was changed with the engine in place. When you remove the right inner fender liner panels you have pretty decent access, although I believe I had to disconnect an oil pipe to get it changed out. You also need to check and see if your new compressor comes with correct oil amount, or if you need to buy oil and put it in. Needs to be correct oil for type of refrigerant. Replace receiver/dryer unit. Grab a set of A/C gauges and a vacuum pump from Harbor Freight and you're good to go. Sent from my VS990 using FerrariChat.com mobile app
I extended the wires and installed a 40A mini circuit breaker. Now I can access it under the panel on the right. I tied it to the Receiver. Way to many electrons trying to get thru at once. I think I'll track it down and maybe install 10ga wire. Sometime.
