danglerb

Ran around yesterday and this morning buying stuff, and dropped off the 928 at the mechanic we use on our Ford's for a change of all the fluids and filters, and he gave me a pep talk on the Sanden AC compressors. They use it all the time on the old hot rods they restore, even with a lumpy cam he says it works fine. They have something like four mounting tabs on the end, so fit just about anything. Haven't made up my mind.

Isn't a filter drier a generic device? Its a can of desiccant with a filter and two connectors.

Is there some kind of mystery to AC that I am not getting?

Peter F

No

/Peter

blown 87

I do not understand why you want to change from stock.

hacker-pschorr

Isn't different always better?

blown 87

Sometimes yes it is, but in this case I really do not see where it is gaining much.

As long as the compressor is supplying liquid freon to the expansion valve at (X) pressure nothing is going to change as far as cooling goes.

If you get a compressor with more capacity you might be able to improve the cooling by backing off of the expansion spring ( I have no idea if the ones on a 928 are set up so you can adjust them or not). I do know that there is some small degree of component sizing that goes into the design of a A/C system.

When I was going to put A/C on my 70 SS 454 Chevelle the Sanden was what I bought for it because of the stories that I had heard from Vintage air about trying to use a compressor that was too big like the old long GM one.

rhys

I can already freeze a side of beef with my stock a/c... more might be just a tad too much.

Mike Frye

Who drops their car off for fluids ?

dr bob

Danglerb reported originally that the existing compressor was damaged (in a separate post, should have been mentioned here), so the hunt is for a compressor. He's looking at options.

Swapping to the Sanden unit requires a bracket and hoses different from what comes on the car. If your hot-rodder buddy is willing to fab the bracket for you, you can certainly get the hoses made for whatever compressor you buy. The Sanden is certainly a fine unit and would be more than adequate for your 928 needs.

The drier, at least in my later car, is used commonly on other German cars. Most notably the 944 in my case. Porsche wasn't in the habit of inventing these from scratch, instead they went to Behr and had them fit components that would do the job. Except for the control head, the refrigeration side stuff is nothing special. Oh yeah, the condenser and evaporator are particular to the car just because of design and space issues. Otherwise, nothing is at all magical about 928 AC.

Fabio421

Dangler... Slightly OT but if you are doing any A/C work, make sure you update to the new refrigerant. And DO NOT let anyone talk you into petroleum based refrigerants to save money. If you don't believe me ask Louis Ott. BTW Louis...Your story made it into Popular Mechanics. I read it in a back issue while at my Moms for Thanksgiving.

fabric

Since you are putting on a new compressor, it makes sense to go to r134. If you have a working OE compressor, from what I've gathered on Rennlist you're probably better off sticking with r12, even if it is a bit more expensive, although that may be picking nits as conversions to r134 with a stock compressor do work.

IcemanG17

I would just get a rebuilt (from ebay) nippondenso 6E71....thats what most 928's take and it works good! Typically they can be found for around $150.....

blown 87

As long as r-12 is still out there, use it.

danglerb

Sorry forgot to mention original compressor is toast, burnt toast, cracked pivot, no belts, no hoses (sheesh no hoses, whats with that?, my memory going I suspect, but I think the compressor fittings were taped over, maybe the hoses tied off where I didn't see them.).

The non DIYer rule.
You pick the mechanic, not the part. If you want good results you have to let the mechanic do what they think is best. That doesn't mean I don't argue with them, or make suggestions, maybe even change their mind or get them to try something, or try another mechanic. You can't ask somebody to stand behind their work and use parts they don't like, or aren't familiar with.

New original parts are the lowest risk most of the time. For a normal person to keep a 24 year old Porsche on the road as a daily driver, you need to be open to more solutions than with a newer car. Some rebuilt parts are better than new original parts, and some modern parts are also better than the original.

blown 87

So true

tomcat

This is to tell you what I did and my short term results. What you do should be based on your own judgement.

This summer I filled my system with R-12 and found I had a leak and was comtemplating spending another couple hundred dollars for more R-12 - after sealing the system. Bought a vacuum pump, guages, o-rings, etc. and was about to refill with R-12. Then some said ester oil was compatible with R-12 and R-134. I figured worst case scenario filling with R-134 was seizing the compressor and finding another one for ~$150. Tried to get as much of the old oil out but my compressor doesn't have a drain on the bottom.

Sealed the system, filled with R-134 and ester oil, and the AC works great. Actually tried it a couple of weeks ago to avoid drying out the seals and it was still spinning and making cold air.

Some people say performance is diminished with R-134. Maybe, but it's more than cool enough for me in 100 degree DC. There are two oils that I know of that can be used with R-134. One will definitely seize the compressor if there is residual R-12 in the system. The other (ester oil) is working for me till this day. Next summer may be a different story, but I'd rather gamble and pay for a new/used compressor in the future if I have to then worry about spending $300 per year on refilling R-12.

Obviously, change the x-pansion valve and drier if system is opened.