This is not a problem. In fact being able to develop enough pressure for the
AC to turn on the next stage of the radiator fan is a good sign. The
pressure developed on the high side of the system is dependent on a number
of things. Outside temp, loading from inside temps, and heat from the
radiator adding to the AC condenser will effect operating pressures. R-134a
does operate at slightly higher pressures than R-12 so increased fan usage
is common.

If you are going to service the AC yourself you should get some training,
get a certificate for handling refrigerants, and get a gauge set and learn
how to use it. There is also a sight glass on the receiver dryer you should
use to see the state of the refrigerant system. The whole trick of air
conditioning is the latent heat of vaporization. Compressing the refrigerant
into the liquid and then letting it absorbs heat and boil off is what it is
all about. Excessive high pressures and too much use of the fan at high
speed is a sign of the system being over charged. The proper way to charge a
134A system to completely evacuate it and then fill with a specified amount.
Typically for 134A you use ~80% of the R12 specification. This is why you
need recovery equipment to service air conditioners.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mister Tom
Sent: Saturday, July 12, 2014 11:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: 87 Westy, A/C Question

In my '87 Westy, I put a couple cans of R-134 in a couple of weeks ago. The
van mostly sat for three years after being converted from R-12 to 134.

The air now blows cold, OK.

Today temps are in the low 90s and I fired it up to see if it was still
blowing cold.

After a few minutes, what I think is the mid-speed radiator fan came on and
stayed on.

When I shut the van off, the van ran for just a few seconds and went off.

Does this sound like the high pressure switch, or an outside air temp
problem? I've heard that the A/C systems don't like to work when it's really
hot out.

Back when I added the refrigerant, temps were in the 80s.

I ran the van for a LONG time and never heard the fan come on.

I do remember the mid-speed fan coming on in the past, in the R-12 days,
when the temp was really hot and we were traveling at 70 mph on a hot night.

Thanks for any help.