I got the cable controlled model. Didn't want to have to depend on the electronic controls. There are two cables; one that controls the defroster circuit and the second which runs up to the hot water shut-off control valve located in the engine compartment. Their is also included, a manual shut-off valve that stops all flow of hot water from the engine to the heater. I can't speak to the efficiency of the heater circuit as I haven't found it necessary to plumb it in!!
As for problems; none....installation was simple using two existing holes from the old heater box as a guide. All hose connections are made from inside the engine bay so you don't have to work under the dash once you've installed the evaporator box. Their dual-purpose bracket (included) allows you to mount both the compressor and the alternator on the driver's side of the engine. The only thing that I really didn't like about the Old Air system was that the high pressure line runs across the firewall and is highly visible. All their lines are already crimped so unless you fabricate your own longer high pressure line, you're limited at where it can be run. All of the lines to the condensor are pre-formed and mounting/plumbing it are straight forward. No cutting holes in the core support; drill a couple 1/8" lower bracket mount holes and you're in business.
As for operation.....it's efficient, brings the cab temp down quickly and most importantly once you're cool, the low fan setting lets you carry on a normal conversation.
On my install, I fabricated a simple alternator mount bracket that lets me run it on the passenger's side of the engine. In addition, I am running a two-groove harmonic balancer from Buffalo Enterprises. This allows me to run the alternator/waterpump/balancer with one belt and the low mount compressor with a separate belt. With the a/c compressor mounted low on the driver's side I could run a power steering pump mounted on the upper position of the compressor mount bracket. It would be driven off the 2nd groove on the compressor. I have some pictures of the setup in my Webshots albums. Doing it this way gave me good clearance between my fan and the drive pulleys; something that you need to consider. Hope this helps.
Dave
