The Stovebolt Site Forums The Shop Area The Electrical Bay Electric A/C on my ‘62 C-10

I’ve been looking into options for A/C on the ‘62 C-10. I’m intrigued by the 12 volt compressor systems. Compressor can be mounted anywhere as long as you can get 12 volts to it. Has anyone tried the all electric A/C units in their Stovebolt ? Curious if they are as easy to install as advertised. Do they play well with a standard output alternator? Can they keep the cab cool in 100+ temps? Not interested in regular A/C, I know how to do those. Thoughts, ideas, problems, etc.

I have one about 30% installed in my 58. I got sidetracked with medical issues, so I don't know how much longer it is going to take.

Thus far I am inpressed with the setup so far, especially for the price.

I will say that it will not play nicely with an standard output alternator. The condensor fan draws 13A and the evaporator fans (there are two in parallel) draw another 10A. The compressor says it draws 60A, but I have not powered it up to verify that yet because I don't have the lines run for it.

I put in a 115A alternator a little while back, so I am hoping that will keep up.

The compressor came with a 75A inline fuse and the condensor fan is powered by the controller built into the compressor. It is a 3-phase motor with a DC controller mounted to the back. I suspect the 60A is pretty accurate because it appears to be using the motor current as feedback for the high-side pressure.

I am working on a write-up for the install that I plan to post when it is done and tested.

I would suspect that in "steady state" operation, the amp draw will be less than 60 for the compressor. That number probably is the starting current and should drop considerably when the compressor is steady. Just as a comparison, a 5 ton residential ac system would normally be fused at 60 amps, of course that is not taking into account some type of "3 phase" magic or ac amps vs. dc amps.

Apples and oranges comparison between a 12V AC compressor and a residential AC system which would operate on either 120 or 240V.
60A at 12V is 720W or almost 1 HP.
60A at 120V is 7200W or nearly 10 HP.
But that doesn't answer Martin's question.

I will measure/profile it when I finish hooking it up and I can give you hard numbers then.

Thanks, I’ll be looking forward to your write up.

What AC kit did you buy?

Looking forward to the results. I think these types of kits have pretty interesting potential.

Very much looking forward to hearing about this also. There are challenges I see but I'm keeping an open mind at this point and trying to be positive. One is output. These compressors output only 20cc. That is tiny and it makes me wonder if you could cool much space with it. A typical mechanical compressor (think Sanden 508) is roughly 7 times that at 138cc and so is the Toyota Prius (which by the way operates on 200+v). So obviously they're going to have to run very fast and even then they will never equal the output, but let's see what happens. You're also going to need a lot of amps if you're battling an ambient temperature of 100 degrees or more. Unfortunately if this amp demand causes your alternator to become a crispy critter, we may not know that right off the bat...although it shouldn't take long.

With alternate approaches, it always comes down to efficiency and size and how to move heat quickly.

Around 6 or 7 years ago I showed folks here using no compressor at all and no refrigerant at all how I could easily make solid ice in 7 minutes...taking a 1.5" x 3" block of aluminum from 70 degrees to 20 degrees in an ambient temperature of 78 degrees. (The COP by the way will usually be around .5, so in an ambient temperature of 100 degrees, 50 is about as low as I can make it go...although some makers claim a COP of .7, I've never seen it happen). All I need is a Peltier device, a good heat sink and a fan (in comparison to your truck's airconditioner please think of this as the condenser unit), a piece of aluminum for the "cold sink" (even though as you know there really is no such thing as cold) plus voltage/current of 12 volts and 7 amps. This is great technology dating back to the 1830s. If I could figure out how to use this and solar energy to adequately cool houses, I'd be living on an island I bought for cash and I'd probably hire Bill Gates to drive me around in my yacht. I can get the efficiency but I (and millions of others who have tried) can't figure out how to make these cool large things. But please take a look below. I could make a pretty good personal ice machine or beer cooler. (even though other methods are more efficient) I have thought for years a small mini-icebox could be made for the AD truck...but you really need to exhaust the heat to the outside or you're just going to be in a loop...taking heat from one area and depositing it back into the same area.

Jon, your Peltier device with a COP of 0.5 is way less efficient that a standard refrigeration system which has a COP of around 3.

So your 12V 7A device (84W) only puts out 42W of cooling power versus the a compressor drawing the same power would give you 252W of cooling power. That's about 0.07 tons of refrigeration or the ability to make 143 lb of ice in an hour. No idea whether that's enough cooling for a typical truck cab. (My math may be a little off, as I haven't been in the business for over 5 years - a little rusty. )

Also no idea how much power a typical 12V compressor draws. Looks like Jason's setup draws 82 amps total, but that's at 115V.
A little rusty on observation as well, I guess. I mistook that 115A alternator for 120V.

Yes, pretty inefficient indeed but the neat thing (in a Science Fair sort of way) about the Peltier device is it chills or heats (if you reverse the polarity) with just voltage & current. In the 1980s these were being experimentally used in fireman's suits and astronaut's suits to try and reduce body temperature.

I think the 115 number in Jason's post referred his 115 amp alternator and not 115V. Everything I've read about this compressor (from people who have posted comments about everything from old cars to RVs to all sorts of things) tells me unless you have a vehicle the size of a Mazda Miata you're going to need 12V and 60 amps to run the motor at 4000 rpm. A good number of people have said theirs had to run constantly at the fastest speed to cool something that would compare in size to maybe a Chevy Nova or a Honda Accord and it didn't keep it cold...just cool. But I don't know where these people were living. Yesterday we had an unexpected cool morning (for August). When I went to the post office it was only 81 F degrees and I could tell the compressor was cycling on/off. Later when the temp got up to 95 F it was running constantly. I saw one post where a person tried one of these in an airplane but learned they must be kept level or they have failure issues.

My 82A is at 12VDC (really 14VDC), but only ~60A of that is compressor, which maths out to ~25k W of cooling.

Coincidentally, that is what the system is rated at.

Martin, maybe you can just open the vent window and drive faster. This is starting to sound like a dangerously complicated idea. What is wrong with a good old swash plate axial piston compressor (I looked that up) running off a good old V belt. Are you going full "E" on us? Like Elon?

I mean COP? Peltier? cooling power? cold sink? 143 lbs of ice per hour?

Kevin is surely an expert. Who knew he was a guru on this stuff. But I fear he is getting over excited and causing Jon to begin to create a new system for AD truck AC.

Do they know you ARE a COP?

Didn't hit refresh before posting...

Jon is on the money. The 115 number above is the size of the upgraded alternator I put in.

I have mixed expectations on the cooling ability of the overall system. The cab of the truck is small and keeping it cool instead of ice cold is good enough for me when the whole setup was under $500 landed.

If I dropped $2500+ on a Vintage Air or Old Air Products system, my expectations would be much higher.

That said, I am very impressed with the build quality and the component quality (in general, not just at this price point).

I was hoping to have it in this weekend, but I ended up getting tagged to rebuild an engine for a missionary friend. Then next weekend is a funeral and the following weekend is the start of the Miss America pageant (my niece is in it).

So I guess my goal now is to get it installed in time to use the heater side for the fall...

A used vintage evaporator underdash (I.E. 60's mustang or Mark IV), a sanden compressor, drier, expansion valve and condensor, all available as DYI, is another way to go. Hose it all up and have it filled with R-134A or r1234yf. R134A still readily available. This DIY method is still done by many. I have done it. Not as cheap as the $500 12V kits I see online. Probably about double but sure has been a proven system here is Arizona.

I can't speak for Martin, but in my case it is for the *lower* complexity.

A larger alternator is 2 bolts, a larger cable to the battery, and retighten the existing belt.

Going to an all-electric system avoids having to change the crank pulley to a 2-belt, figure out a compresor mount, and get everything aligned.

The electric compressor just bolts to a flat surface wherever it is convenient and has 3 wires.

On my TF, I have plenty of room under the hood, but I could see this setup having even more value on an AD where space is at a premium because the packaging is much more flexible.

I won't say that it is for everyone, but it seems like a worthwhile option to investigate. More choices make everyone's lives better.

And maybe it will be an epic flop. At that point it will be $500 wasted, but at least it will be tested and found wanting.

As Jerry likes to say "TEST, DON'T GUESS".

Trying a $500 item to see if you will like it is not the kind of test Jerry is speaking of. He is talking about troubleshooting, not product reviews. These 12V kits are a little Red Flaggy when only sold by Walmart, Ebay, alibaba and Amazon

Amazon
Approx getting 4 "stars" with 1 review, another has 5 reviews another has 7 reviews.......Not all were happy, NOT a reliable sample size at all.

AI says: 12V car air conditioners can be a good option for certain situations, particularly for vans, RVs, and off-grid setups where traditional AC systems might be impractical or inefficient. However, they often have lower cooling capacity than traditional AC systems and may require careful consideration of power consumption and battery capacity.

Why is no one comparing BTU's ???

@Bartamos: the last time I built a system from parts like that, it was about $1400. Cheaper than a custom, drop-in solution from a big name, but more than the universal electric kits.

I agree that it is a perfectly fine solution that has worked for a lot of years and I would not discourage someone from building one of those if that was the direction they wanted to go.

I suspect it could be done a bit cheaper now because the evaporator/heator core/fan unit that the electric kits use are available by themselves for pretty cheap.

They are also sold with good reviews from Speedway, Summit, and other automotive sources.

You can find negative reviews on Amazon or Ebay for anything.

Given Jerry's discussions of buying and testing various distributor options, or engine component options, I would say that this is exactly what he proposes. Build a system using the components that you think should work and see if it performs the way you need it to.

Either way, Martin expliclty asked if anyone has experience with the electric units because he already knows about traditional setups, so we should probably get back on-topic before we get our hands slapped.

Edit: You appear to be under the impression that this was a random purchase on a whim. All electric AC systems for cars have been used for ~20 years now and between economy of scale and improvements in the technology, this is an entirely plausible thing to build and have work. A great deal of research has gone into this decision

All good info for Martin. Sorry Fibonachu, I added an edit to my previous post before I saw yours.

WOW , you are posting so fast I can't keep up. Hey I'm 79 and just had cataract surgery. Yes he did ask about 12V, but you know we old timers hate change.

Where are all the stay original, nostalgic, keep the proven old ways, KISS, guys when I need them?

To answer your question re: BTUs.

I have looked into the rated/claimed BTUs on both traditional and all-electric systems and find that neither one reports realistic/plausible numbers.

It is like going to walmart and buying a 5HP hand vacuum. There is a test that they will point at that outputs that value, but it is meaningless and deceptive.


I have intentionally not posted the BTU numbers from either because I do not believe them.

You can get good BTU numbers for household systems because there is a legally mandated methodology for it. If such a mandate/standard test exists for automotive systems, I have not seen it.

When you are buying anything with an electric motor, drills, saws, sanders, bench grinder, shop vac, etc...you only look at AMPS. AMPS is torque. HP has "power factor" and "efficiency" in the calculation. As you say, deceptive.
Compare amps. Buy big amps. RPM's are relevant on some things. If you are comparing different brands and one says Amps and the other says HP, dig into it until you see the amps.

This has some interesting information that seems relevant. This SAE study indicates that 7k BTU should be plenty for 100°F+ weather. All of the tested vehicles (Impala, Camry, Prius, Altima) have more internal volume than one of our trucks.

That number is less than I expected. I would be interested to know more details about the test methodology, but what you see is what I got.

SAE Study of AC Requirements

7000 BTU is approximately equal to 2000W of cooling (there are some assumptions in that math, but I don't have a better way to try and compare them).

With the COP of 3 from Kevin above, that works out to about 667W.

Divide that by 13VDC (nominally 12, a lot of alternators put out 14, call it 13 for convenience) and you get 51A needed. With the nominal 60A that this is rated, that is 15% overage for efficiency losses and/or rating estimates.

All things considered, that seems pretty plausible to me and correlates to the SAE rated needs.

@Bartamos: Agreed. But as far I know, there is not an equivalent to amps for measuring effective capacity on these systems. BTU *should* be that number, but it is consistently fudged.

That was me but after 40 years of staying original I put a 235 in my old 216 truck and currently installing an AC (with pulley compressor). At a certain age comfort starts getting important! My truck was always a lousy "original" candidate anyway. Guess I just enjoyed banging my head against the wall.

AC will include switching to alternator also. Generator was always rock solid dependable though.

Close enough for me Skooter. I'm not a zealot about "original". I have done a restomod or two and also add safety and comfort items. I like 12V and alternators. But stay with body and interior as original as possible. As for A/C, you can stay near "original" with 60's trucks. They had factory air and the aftermarket provided underdash units. As usual the choice is up to the poster and since there were no members who have done it so far, only speculation and technical talk about if 12V Air may or may not be suffice, I supplied what info there is on the internet and AI. Then was suggesting to Martin to reconsider Belt drive with a cool chrome underdash evap/blower it a light hearted way. He and I are friends and I hope he does not take it as offensive. Just blogidation. Looks like everyone is waiting for Fib to give his analysis.

Whatever A/C one decides to go with in an old truck, whether belt driven or electric compressor, one needs to see to it that the old truck isn't drafty around the doors or through the many holes in the firewall or anywhere else.
Insulation everywhere would help too.

I appreciate all the civil discussion on this subject. My only reason for considering the all electric A/C system is pure laziness. I am of the age where turning wrenches is not all that enjoyable especially since my shop is the great outdoors. The electric units look to be doable in a weekend by myself. I admittedly find myself over my head when trying to decipher all the numbers looking for the highest output possible. I have 3 vehicles I’m looking to add A/C to and at $2000 per vehicle for conventional setups it is beyond my budget. So, if a $800 all electric unit will do the job I will be happy. Thanks again for all the responses.

Hang a swamp cooler on the passenger window.

Otto, being from Hotlanta, I'm surprised you suggested that. Swamp coolers don't work well in high humidity areas, and Georgia sure qualifies as high humidity. A reasonable option in the Southwest where you can't wring a cup of water out of the air from an entire county.

I know but he's on Oklahoma. Isn't that a "dry heat" area like Texas? Really just joking, though.

Most every one I see for sale is priced like they're made of solid gold! Certainly as much as a complete underdash AC from fleabay and others. ($550 for mine) Pulley or electric, they're priced about the same.

I agree that you sbould be able to. I got slowed down because I was individually experimenting and profiling each part on my bench supply before actually getting down to business.

Then I got sick and have not getten back to it yet.

Good news, the system is installed. Fairly simple. The system I bought had the fittings already installed on both ends of each hose so the hoses were exceptionally long. I cut them down to fit the application better and had issues finding the proper size fittings for the Chinese hose. Apparently not a standard size. All in all I’m happy with the results.

Martin - Glad to hear you got the system installed and are happy with the outcome. At our recent Stovebolt MBA Roundup, Kevin "Shakey61" presented an excellent tech session on a 12V A/C systems, which a lot of folks seem to be considering. He had a complete functional demonstration system on a display board, to help folks visualize it all.

Could you - would you take and post some pictures of your installation? I think it would be great food for thought for folks considering an upgrade to be able to see one in place and functional.