A/C question 12 or 24 Volt Compressor

I am in the process of replacing my A/C compressor and the Supplier wants to know if the A/C fan clutch is 12 v or 24 v. ? I see the replay is 12v and 30 amp. but not 100% sure of the supplied voltage to the Fan clutch. anybody purchased a compressor lately? Or know the proper voltage?

Thanks.

84 Mondial QV

 

12v system.

What make and model compressor are you looking at? There is a good choice available these days. I'm thinking of replacing a couple of compressors with some new Sanden compressors (choice of 5 or 7 cylinder type) and they are quite cheap (here in the UK I can get them for under US$200). Previously converted my systems to R134a BTW.

 

Yep, 12v.

Why are you replacing it? Just curious.

 

I always thought we have about 10.5V.... ;-)

 

Thanks!

It is a Sanden 508 with a single groove pulley The exact model number is rubbed of the unit, but the casting stamping is SD 508 The current compressor is seized up, as it has been inoperative for numerous years according to the PO. I can get the clutch to activate with a 12V jumper, but the compressor will not turn over due to the apparent frozen piston.

84 Mondi QV Cab.

 

The SD5 series are 5 piston (I mentioned cylinders previously when I really should have said pistons) and the SD7 series are 7 piston. I'm thinking of trying the 7 piston type if they will work on these A/C systems, my theory being they may be more efficient - will be researching a wee bit more.

 

What belt type and size does the Sanden Sd508 run with?

 

Your clutch and clutch coil will interchange with a new or rebuilt replacement Sanden compressor.

Sanden has changed its numbering system a little bit, but there is a direct replacement for the SD508.

Typically, it is hard to find a new compressor with the Ferrari clutch belt pulley dimensions, but your Ferrari pulley will fit on a Sanden replacement compressor.

The clutch coils are interchangeable regardless, just use the correct voltage. ie:12V

If your clutch, pulley, and coil are good, just install them on the new compressor. It is very mechanical and not very technical to change. Instructions are on the internet.

Make sure you ground the compressor body to the car motor with a ground strap or copper wire. Do not rely on the compressor mounting bracket to be a sufficient ground to energize the clutch coil.

This is a great resource:

http://www.sanden.com/objects/Sanden%20Singapore%20SD7%20Series%20Compressor%20Catalogue.pdf

There is also a lot of Sanden engineering information on the internet.

If the compressor that is on your car is the original - keep it and have it rebuilt later. It has some older engineering specs which make it better for the Ferrari installation, but a newer model will also work fine. The older model has a different clutch shaft drive key set up to drive the wobble plate drive gear inside the compressor. The newer key way design was made so the newer compressors would run quieter.

The Ferrari compressor rotates in the opposite direction of most automobile a/c compressors because of the way it is reversed mounted on the motor. That is a bit hard to think about, but the compressor will run and work/compress the freon rotating in either direction.

Very important. Use the correct compressor oil for which ever refrigerant you decide to use. R12 and R134 use different compressor oil.

There are also some other threads on Mondial and 3X8 a/c systems in Fchat that may help you.

Good luck,
Deep river Garage
Jerry

 

I have a Napa belt #7340 Mine is the single pulley type, fits great

 

[the compressor will run and work/compress the Freon rotating in either direction.

Very important. Use the correct compressor oil for which ever refrigerant you decide to use. R12 and R134 use different compressor oil.

Great info. thanks.

One question, if the compressor rotates backwards then will the suction / discharge ports be opposite on a Ferrari then a stock SD 508 unit spinning the correct way (non-Ferrari application) ? Hate to put a can of r-12 on the high pressure side when filling.

I plan on using r-12 refrigerant, is Ester 100 still a good lube, thought it was compatible with R12 and 134's

 

The discharge and suction ports will remain the same regardless of the direction of rotation of the compressor.

Ester 100 is a synthetic oil and is noted to work with either R12 or 134a on several websites.

http://www.johnsens.com/uploads/files/regulatory_lubricantguide4.pdf

The Sanden reference manual noted above also has a section on proper refrigerant oils.

The angle and width of the belt should match the pulleys.

If I recall correctly, the Ferrari a/c pulley/belt has a 60 degree pulley angle and is 11m (a little more than a 3/8" belt) wide at the outer edge of the belt groove.

The belt angle is a bit more important to match than the exact belt width. A 3/8" width belt is probably as close as you will find in general replacement belts, unless you buy an actual Ferrari replacement belt, which may in the long run be best to match the angle and width. A wider belt will run higher in the pulley, narrowing will run lower. The more belt contact you can get on the pulley, the better.

http://designcenter.gates.com/wp-content/uploads/2015/05/Gates-Belt-ID-Chart.pdf

The 34" length belt will be in the ball park. If you don't have enough adjustment to get it on, or too much length to get it tight, you may have to buy a different length belt.

Ferrari a/c belts are noted to make a metallic clicking noise, especially when cold. A tighter belt may help, but that is a bit harder on the belt and bearings.

If your a/c system has been open for a while, you may want to flush the system, ie: evaporator, condenser, and refrigerant lines, with an appropriate refrigerant solvent. It would probably be a good idea to replace the filter/drier, too.

I hope this helps.

Good luck,
Jerry
deeprivergarage