Thread: Electric AC compressor

I saw one go into a Torana recently. They're pretty thirsty, but then it's often easier to put in a bigger alternator than it is to find space for another mount and belt.

OKA has air. Yeah, right. Hard to believe they come from your neck of the woods. And were used on mine sites. I don’t know if the original one actually works because the whole thing is nightmarish and I would like to start from scratch. The alternator upgrade would be easy, but if they’re thirsty then my idea of running it engine off probably wouldn’t fly.

Yes I have. Not in an OKA though

I believe I once did a write-up on the setup in my Range Rover P38 on here but I can't find it so I'll jot down my experiences here:

1. power hungry indeed
2. not as efficient as a split unit for a house
3. can work with engine off

About power, the most seen/used AC compressor is about 18cc and pulls around 97A according to spec, they can even go over. Add to that the rest of the car that needs to run and you are talking serious power. My standard 120A alternator for my range was certainly not up to the task and an aftermarket 200A unit had overheating issues when loading up to 180A or so. It is not easy to find after market uprated alternators that will do their max rating at 100% duty cycle! I ended up using two hitachi alternators from a VW phaeton which do 190A each and are water cooled so I could plumb them into the cooling system of the car and keep things stable with ample overhead. (I had the space for the original AC compressor for the second alternator)

Overall, if you look at the specs for the 18cc unit mentioned above it will have a COP of around 2.7 that is a far cry from a decent mini-split unit for a house which can go up to 5. Thing is of course that I used the existing HEVAC stuff already present in the car and simply rerouted the piping and plumbed in the electric unit. But still, even with the best conditions (ie sized evaporator and condenser) you would still not get the best efficiency possible. This might not be a problem as long as the engine is running but my third point:

The beauty of an electric setup is that it can work whilst the engine is NOT running, as long as you have a beefy battery bank. For me that was the reason to replace the belt driven AC compressor to begin with

Regarding cooling capacity; I found the unit on the highest setting to be quite sufficient to cool my range down to acceptable levels in 35c heat. I have not been able to try it on warmer days. The unit is capable of 3.17Kw of cooling according to the spec sheet. I reckon that should be enough at least to keep you cool in all but the most challenging conditions.

The beauty of an electric AC compressor is that you can place it virtually anywhere you have the space for it. It cools itself with the AC gas so it can operate even in hot areas like an engine bay (mine sits next to a hot V8). An added benefit is that the condenser can also live anywhere you like, on the roof, underneath the car, etc. It does not have to sit in front of the radiator where it is generally placed in most vehicles that come with AC. The compressor itself is not really that loud, I should think the OKA will be louder anyway. The added fan(s) for the condenser however can add quite a bit of noise since you need ample airflow to cool the thing down properly.

Anyway, should you want to know more details just let me know, I worked on it for months and experimented quite a lot with it as well (including blowing one up...)

Cheers,
-P