Re: "Special" items when converting to 12 volt?

Posted by HH56 On 2008/8/29 9:15:06

I think most of the amp requirement is going to be the blower motor. If you'll check out Vintage Air schematics, on most there's a 30 amp circuit breaker directly to the blower speed control switch with some minor variations. In some 70-80's GM products, there was even a separate fused supply for high speed blower operation.

Here is a Sanden clutch spec sheet for a 12V dual groove assy. This is from their latest FLX7 modular series, and all clutches in this series ran 43-49 watts at 12V. Using the formula Amps = watts/volts the draw will be 3.5-4.08 amps. Even their older less efficient units probably won't go over 5.

There are commerical 6 to 12 volt converters available but most aren't geared to run more than a few amps for radio or tape deck type things. Largest one I saw doing a quick check was 8 amps.

EDIT: I did try to measure current but don't have the adapters here to complete circuit on dual pin plug on Ford and can't access the Dodge compressor without a lift. Also found a resistance value for Sanden clutch coils. Should have a resistance of 2.8-4.4 ohms. This also calculates out to max 4.5 amps at 12V.

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