308 Air Conditioning Question

First of all why is it empty? If you don't know, don't spend the $$$$ for R12 until you do know. DO NOT convert to 134 unless you want it to blow warm only.

The switch really should be replaced while the unit is empty too.

 

That's a rather gross overstatement. I converted my system to R134 the last time my compressor had to be replaced... and it blows VERY cold and maintenance on the A/C is now much less expensive.

 

The changeover to R-134a is more involved than just vacuuming the system and changing the fitting adapters. <grin>

The simple answer to ScottC's question is yes, there is a low pressure switch located at the receiver/drier up front and you can bridge it to trigger the clutch (if the electrics are good and the inside fan switch and temp control are set to cold) to get the compressor to aspirate R-12 liquid through the low side fitting.

Going back to Tommy's post, the most prudent approach (and least expensive) would be to hook up a set of manifold gauges and see if the system has any pressure in it. If it's very low or non-existent, pull a vacuum with a pump and see if it holds. That's the best way to check for leaks. OTOH, if you have 10 psi on the low side and over 100 on the high side, add some and see what happens.

-Peter (first Ferrari job I ever did was A/C repair on a 308GTSi in August of 1981... wow, I feel OLD!)

 

It isn't in 2 of my other cars. I went 134 and never saw the same cold temps. Same with a friend of mine. 2 cars, 2 "cool" a/cs. It has to do with the chemical volume differences or something. Anyway, I paid to "re-convert" to R12 and now I am cold and happy again. The 308 has always been R12 so I cannot speak from experience for it.

 

Maybe... I do know it seems to need to be fully topped off and is quite sensitive if the freon fluid is low at all. So I have my mechanic also check it when the car is in the shop for other reasons, and have had no problems.

 

i would agree. switched to freeze 12 (which is a combination of 12 and 134) and the temps didn't get nearly as low as with 12. Finally switched back to 12 and got back my previous cold temps.

otoh: I added vintage air to my corvette with 134a from the getgo, and it blows very cold and I have two other classics with 134a and they also blow cold. but 134a in the ferrari raised the temps at least 7-10 degrees. go figure.

 

It has to do with R-134a requiring more evaporator capacity than those designed for use with R-12. Since a majority of the Ferrari evaporators are on the small side anyway (for packaging reasons more than anything else), they're the ones where you see the most difference.

-Peter

 

when dye checking for leaks be sure to use nitrogen not freon.