Monday, May 29, 2006

Project 1 - A/C Conversion R12 to R134

OK. So, I've decided to do the paint later in the year. That means I need to make it drivable. A car is not "drivable" in Houston if it doesn't have A/C. This car came from Michigan, so the A/C didn't work at all.

I took it down to the local Auto Check and had them recover whatever coolant was in the system. I then purchased a Kuehl drier, some ester oil and an R134 Conversion kit from Griffiths (see

They didn't include quite all the o-rings I needed so I bought another couple of sets from AutoZone.

I then swapped out the drier. Take a look at all the nasty coming out from behind the old one. It's that pile of dirt on the floor there. The drier is retained against the fender well by two hose clamps. These were turned too far to get a screw driver on them and they had round heads so I couldn't use an articulated socket. I had to use the dremel cut off wheel to cut the old hose clamps. No big deal. I just replaced them with new.

I torqued the hose fittings back up using a crow's foot. I wish I had a set of flare nut crow's feet but I don't. Oh, well. At least I had flare nut wrenches to get the hoses loose.

The next step was to remove the compressor and drain all the oil out as the oil in an R12 system is not compatible with R134.

Here's the compressor: Swap the O-rings while you're there. There are 6 of them. Two on each of the mounting plates and one at the end of each hose.

OK. Now lube up all the o-rings with ester oil, make up all the fittings, and torque them to spec. Use a torque wrench - there's no such thing as "it's tight enough". Also, it's a good idea to coat everything with antiseize. The fittings on the drier were galled slightly and I had a heckuva time getting them free.

After everything is back together, evacuate the system. I bought a starter kit from AZ Mobile Air. See the link:

Here's the pic:

I drew it down to 3 microns for 15 minutes and let it set. It held for 30 minutes. I guess that means it's sealed. At that point, I evacuated it for 3 hours. There are two ways to boil water. The first is to raise the temp. The second is to lower the pressure. Evacuating the system allows the moisture present in the system to be boiled off. This makes it all nice and dry. Pv=nRT! After that, I loaded up four of those 1 lb r134 containers and that's that. It now blows 58 degrees. Not great, but hey, it's as cold as the r134 system in my Miata.

Maybe today, I'll load another bottle in. I wasn't getting complete transfer of all the refrigerant.



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