Has anyone installed one of these kits?
I'm contemplating either rebuilding the existing original AC heater box and install a sanden compressor in place of the original large compressor.
This kit has an attractive price point and appears to be able to use the existing ac dash outlets.
This is going on a driver 1970 Charger.

Thanks in advance!

I did not install the Classic Auto Air Perfect Fit kit in my 68 Barracuda; but I have worked on it and contacted CAA. Their phone tech support helped me replace the servo motor that burned out.

The issue with the CAA kit is the AC power circuit. I believe it runs through the ignition switch. So when you turn on the AC, your electrical system takes a big hit (at least mine does). You can download the directions and wiring diagrams from their website and compare them to their competitors.

I believe Vintage Auto Air wires the power circuit differently. That is worth checking into before you buy either system.

To cure the big hit on the ignition system you could just add a relay to the compressor wiring circuit.

Just adding a relay won't fix it.

What I think I need to do is tap into the battery power circuit coming into the cabin instead of using the factory 'heater' circuit. The factory 'heater' circuit gets its power from the ignition switch, which then goes to a factory splice (providing power to several other circuits), then to the fuse panel (where it provides power to two more circuits), and finally to the 'heater' circuit wire. The CAA system uses the factory 'heater' circuit wire to supply power to their system.

The future plan is to use a relay in the new 'heater' circuit, which is now coming off of the battery power circuit. I could put a fuse in that circuit and bypass the ignition switch and factory fuse panel (aftermarket fuse panel now). At that point it would be a stand-alone circuit.

I already have the relay to do it. I just need to climb under the dash and wire it up. The part that I still need to figure out is how I will use the blower switch to trigger the relay.

This is why I suggested to check out the Vintage Air kit. You shouldn't have to do all of this when you spend over a thousand dollars on an AC kit.


The compressor wiring circuit (I assume you mean the circuit that enables the compressor clutch) doesn't appear to be the problem. I tested that circuit without turning on the blower motor and it didn't hit the system the way the blower circuit plus the compressor clutch circuit does. The CAA has the AC clutch circuit fed through the same factory 'heater' circuit. So when you turn both on, that is when you get the big hit. Turning only the blower or only the clutch on doesn't seem to do it.

I got them installed on a 67 Coronet and a 68 dodge charger and they both work great.

I had to add a pusher fan on the condensor of the charger because at idle the stock fan didn't pull enough air through and the a/c would get warm.

Putting the relay in the compressor clutch circuit will take half the draw away from the heater circuit. The heater circuit would trigger the relay which feeds the power to the comp clutch from the battery not the heater power.

Stumpy is correct. The heavy draw on your system is the compressor clutch. Instead of the ignition harness providing it power, the ignition harness lead inside the engine compartment would energize the relay and the compressor gets power right from the battery just like wiring in an electric radiator fan or H4 headlamps. No getting under the dash on this one.

OP, please update this post when you decide. I am planning to go the CAA route too. I have my box rebuilt and compressor installed. Detroit Muscle Technologies has a GREAT rebuild kit for your box.

Thanks for all the info and heads up everyone.
I do agree with the AC compressor clutch being the greatest initial amp draw as well as the blower being the greatest sustaining current draw. Sound like relays to make then get power straight from the battery and possibly using a delayed timer relay on one of them to stagger when they come on.

I looked into Vintage Air but they do not seem to have a kit for B bodies. I'll call then and check.

Ropam, thanks for the input. So you get good airflow from the vents I take it. Never had a Mopar with working ac. Be nice for a change. You also answered another question I had, the need for a pusher fan on the condenser. Thanks!

Big Bad Bee, I was considering rebuilding the orig box with the DMT kit. Looks a bit daunting and I guess I was looking for the easy way out.
I'll post with which way I decide to go and the results. Thanks

You won't be able to use a relay on the heater motor because of the different speeds but with a relay on the compressor it won't be necessary.

If the B+ input to the blower resistor comes from the ignition switch, I would try to get a relay placed in before the blower resistor so the ignition switch only powers the relay and the main power to the blower will be straight from the battery, fused of course.

I have the Classic auto air kit on my Challenger. The kit works well for the most part. The controls are a bit funky. Also, I have burned out two servo motors. I asked CAA about this when I ordered another servo, and they felt that the problem was caused by starting the car with the A/C on. They said that the voltage fluctuation from starting the car burns out the servo. Seems possible. To prevent this, I ordered a $4.00 5 second delay relay from amazon. I haven't installed it yet.

Great info! Thanks for sharing your experience and looking out!

If you want to go the easy route, you either need to ship your box to get it restored or just buy the compete kit from CAA.(but then your old controls won't work). Neither one would be any fun in my book and you gotta open your wallet WIDE! I figure I had 12 hours into mine because I didn't know what I was doing. You need to clean out both cores and pressure test. You can have a radiator shop do this if you want. I used mineral spirits followed up with lacquer thinner. You need an FSM to set up the linkage correctly. Not rocket science. I found it challenging but fun. Kind of easy. Realize I rebuilt my 727 after that. I don't get skeered easy...