Air Conditioning Log Out | Topics | Search
Moderators | Register | Edit Profile

Australian RR Forums » Miscellaneous » Threads to 2010 » Air Conditioning « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Bill Vatter (66.20.177.234)
Posted on Friday, 12 July, 2002 - 11:15:   Edit PostDelete PostView Post/Check IP

The following comments are from my study and experience with fitting air conditioning to a Silver Wraith (WGC66).

There is no direct kit of parts that I am aware of, nor could there be considering the coachbuilt nature and differences between individual cars. Kits available for the steel bodied cars are not exact and require a bit of field engineering to complete the installation. As a result, the project is time consuming. I probably spent over 100 hours altogether. A friend who operates a repair shop put a system into a pre-cloud car for one of his customers. He now says he will never do it again. His mechanic took 80 hours to do the work. The customer was angry about the cost, even after my friend discounted the labor charge so much he lost money. Overall a bad deal for everyone.

The pre-cloud cars do not take well to the installation. Bottom line, these cars were not designed for it and capacity is marginal in several areas:

1. Adequate space is hard to find.
2. Electrical capacity of the early cars is very limited.
3. Engine cooling in very hot climates will be challenged, and the car will certainly overheat if the cooling system is degraded.
4. The passenger compartments are not very well insulated and there are typically many air leaks, which means a high output unit or dual units will be needed.

However, if you decide to press on, the following are some considerations you will need to address:

Front, rear or dual unit? Only the dual unit will provide fast cool down and comfortable temperatures throughout the whole car on a hot day of 35 C or higher. The front unit is going to be hard to hide unless you discard the factory radio. The rear unit will take a lot of space from the boot. Unless you get creative with ducting, both units will only cool the space very close to the evaporator. I selected a rear unit and made ductwork that runs from the package shelf along the roof to a point just behind the rear doors. The ducts point the air at the front seat passenger and driverís heads.

The 5 inch dynamo is rated at 27 amps. Probably operating it at a steady load over 22 amps (80%) would place the dynamo at risk of melting armature solder. Air conditioning electrical loads are 4 amps for the compressor clutch, and either 4, 8, or 12 amps for the evaporator blower on low, med, or high respectively. The ignition system takes about 3 amps, leaving very little to operate the lights, which probably need about 12 amps. Donít even think about playing the radio or anything else. The 4 ½ inch dynamo is simply not adequate. In my own car without setting the regulator up for increased load (a very bad idea that could lead to dynamo failure) the dynamo just keeps up at 0 amps charge/discharge when the car is running without lights and the blower on high. At night it can barely keep up on low speed fan, and any higher fan speed will drain the battery. If you use a power condenser or an electric fan ahead of the condenser there will certainly be insufficient electrical capacity. The solution to this problem is of course to change out the dynamo for a 50 amp alternator. Of course you will need to fix the diodes in the alternator to make it a positive ground machine, you will need to find an alternator pulley to accept the wide fan belt, and you will need to fabricate a mounting bracket. Of course a non-authentic alternator is a maximum deduction for the missing dynamo if you have your car judged. For my own car, I use the standard 5 inch dynamo ( I cherish authenticity) and I am very careful with what I turn on. I run without instrument lights much of the time at night, check the battery gravities frequently, and often freshen up the battery charge over night in the garage. This arrangement isnít very satisfactory, but I get by.

Where are you going to put the condenser? There are two choices, ahead of the radiator, and somewhere else. Somewhere else requires a compact unit with its own fan (a power condenser), which draws another 10- or 12 amps, and this is unacceptable unless you get an alternator. My condenser is ahead of the radiator and I do not have an auxiliary fan. I must watch the engine temperature, but it has not boiled yet, so I guess this is OK. On a flat road at 65 mph, the cooling system will run 85 C on a 35 C day, which is OK, but it will get hotter if you are stuck in traffic. (I think my cooling system is in pretty good shape.) I have gotten over 95 C and turned it off when stopped in traffic, but after reading Norman Geesonís discourse on the cooling system of these cars, I think it would be smarter to turn it off at 90C. Of course if you need to turn the A/C off under these conditions, you might reasonably ask what good is it? Also, if you use a dual unit, the single condenser in front of the radiator will not be adequate for the A/C system. (My condenser was custom made for me and covers the radiator matrix, no more, no less, and The high side A/C pressure is close to 300 psig on a 35 C afternoon with the car stopped but running at 1500 rpm.) People use smaller standard condensers, but I think that would be very marginal.

R-12 or R134A? R-12 is in short supply and very expensive. It is not environmentally responsible to use R-12 I think, but R-12 is more heat-transfer efficient. I use R134A and we get by.

Another point to consider is the location of the compressor. This should be to the left side of the engine. It must be driven from the water pump pulley (weld an extra sheave onto this pulley) and therefore the left side will actually reduce the load on the water pump bearing a little because it is opposite the dynamo. You will need to move the fan forward with a spacer you fabricate

I bought my parts from Classic Auto Air Mfg. Company in Florida. I had to field engineer it together, but I got it in there. The compressor bracket they provided was in two pieces that I had to weld together once I trial fit the compressor in place. There is very little room for the compressor and it must be positioned with precision.

Well thatís my summary. Not very good, but then without it my wife would not go driving with me in the summer, so I suppose Iím satisfied, and I would do it again if I had to.