John - Extract from response I sent to Tom:

Check what compressor it is. More than likely, it will be a sanden SD709. Hope it's not an SD 509 (R12!!) Not quite sure, but I think those compressors came with a High Pressure switch on the compressor itself. I'll check if you can give me the comprssor model. If not - the high pressure switch should be located as close to the compressor as possible - and at the worst case at the very least BEFORE the condenser.

Low Pressure Switch should be on the suction (cold) side of the compressor pipework. Either right at the compressor suction (desireable) or in the line between the compressor and the evaporator. The Low Pressure switch protects the compressor against loss of refrigeant charge & (hence loss of oil circulation). We all know what that means!!

Also - there is not a direct relationship between outside air temp & vent outlet temp in the car - they are related but there's a whole lot of other factors thrown in as well. Basically speaking, any good A/C will have air of the evaporator at about 11-12oC. Allow 1-2oC heat gain in the ducts - you should have 12-13oC out the vents. The harder you rev the engine, the colder the air will get (to a certain point)

PS. To convert oC to oF - multply oC by 9/5 & add 32. Go METRIC you bastards!! - ha ha

David Del Ben 85 Vanagon

-----Original Message----- From: jhlauterbach [SMTP:jhlauterbach@email.msn.com] Sent: Monday, September 04, 2000 12:54 PM To: David Del Ben; vanagon@GERRY.VANAGON.COM Subject: Re: Re: D.I.Y. R-134 Kit AC Recharge advice

On the earlier Vanagons, A/C was dealer installed and no high/low pressure safety switches were included. On my '84 I watch outlet duct temp versus outside ambient to monitor performance. For example today the outside air temp was in high 80s and outlet temp was in high 50s. This appears the norm with my system (Freeze 12 refrigerant). Whre would you put high/low pressure safety switches?

John Lauterbach Macon, GA ----- Original Message ----- From: "David Del Ben" <ddelben@AIRINTER.COM.AU> To: <vanagon@GERRY.VANAGON.COM> Sent: Sunday, September 03, 2000 7:07 PM Subject: Re: D.I.Y. R-134 Kit AC Recharge advice

> Tom, > Would suggest that 'blowing a hose after a while' had nothing to due with > the R134a gas. At 60oC [140oF], R134a is ~230 Psi, R12 is ~210 Psi. If > she's gonna blow at 230 Psi, she'll also blow sooner or later at 210 psi. > Hose blowout would more likely be caused by poor qulaity hoses, poor > workmanship, incorrect crimping of hose, etc - any number of factors. > What is 80% charge? Don't even have a clue what that refers to so you're > going to have to fill me in on that one. > Fan will normally run on high. Your getting rid of all that heat in your > cabin through the condenser - gotta have air to take it away. Also depends > on what the ambient temps are -you didn't mention this? > All A/C systems will/should have a High Pressure Cut-out switch to pro tect > against excessivly high pressures. 'Don't leave home without one' > Why: > 1. You might be running in the Sahara desert and its 60oC (140oF) outside. > Your A/C isn't designed to run to those high temps. You'll damage your > compressor, blow a hose, develop leaks, take your pick. > 2. You might get a newspaper blown in front of your condenser which stops > the airflow through it - refer to item 1 for consequences. > 3. You might get a blockage in your piping somehow - say goodbye to your > very expensive compressor > > Need I go on - get a High Pressure Switch. Anymore questions - just email > me. > I design Bus Air Conditioners for a living. > > David Del Ben > 85 Vanagon > > -----Original Message----- > From: TSmith5041@aol.com [SMTP:TSmith5041@aol.com] > Sent: Friday, September 01, 2000 1:10 PM > To: ddelben@airinter.com.au; vanagon@gerry.vanagon.com > Subject: Re: D.I.Y. R-134 Kit AC Recharge advice > > Have successfully converted my van's a/c system to R-134A. 1st attempt blew > a > hose after a while. Had them rebuilt with modern barrier hose. I went with > an > 80% charge but the hi-pressure switch runs the fan on high a lot. The EPA > web > site on conversion mentions using a cutoff switch on the compressor to > control excessively high pressures. Anyone have any thoughts on or > experience > with this? > > Tom Smith > 83.5 Westie