Just got my monthly Jegs catalog and they are featuring
their electric a/c unit. It does draw a lot of amps but
might be the perfect thing to avoid many of the pitfalls I
read about here with space, brackets and location of
condenser. Looking for feedback both positive and negative
on this item. I thought It could go in the trunk but they
mention an aera with a lot of air flow.
In reply to a message from The Jag Man sent Tue 18 Aug 2015:
That’s just the compressor…you need some air flow, but the
condenser is what needs lots of air flow.
The numbers don’t seem to add up. It’s power draw is about
350 watts at 14V, or just under 1/2 horsepower.
It claims 6613 BTU/hr, but a typical high efficiency unit
(energy efficiency ratio of 10) would only produce about
3500 BTU/hr–so this seems optimistic.
A typical belt-driven unit like the GM A6 (used in the XJ6)
consumes 3-5 HP but delivers 27,000 to 42,000 BTU/hr over
the range from 2000 RPM to 4000 RPM–5 times the cooling
claimed for this unit.
I suspect it provides an honest 1/2 horspower’s worth of
cooling, but that’s probably not enough. IMHO.–
The original message included these comments:
their electric a/c unit. It does draw a lot of amps but
might be the perfect thing to avoid many of the pitfalls I
read about here with space, brackets and location of
condenser. Looking for feedback both positive and negative
In reply to a message from The Jag Man sent Tue 18 Aug 2015:
You will need to change to an alternator of 85amps or more.
Compressor needs air to keep cool, cannot be in a confined
space. Will drop fuel mileage, as per the new cars with
A/C. Car itself will have to be changed to negative
ground. Other than that, they work well, just a pain in the
electrical system.–
LarryK, MK 1 & 2, XJ6, XJS-V12, started with XK 140 in 1965
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In reply to a message from The Jag Man sent Tue 18 Aug 2015:
A lot would depend on which model Jaguar you have .
I put a/c in my MK VII. Initially the condenser was in front
of the radiator [ conventional position .] A/c worked well but
the hotter the day when you need a/c more , the hotter it made
the engine. Early Jags had radiators with a small frontal area.
So I moved the condenser [ well by now 2 condensers in
series] to under the sill on the passenger [ LH] side] with an
electric fan above, trial and error showed suck air up worked
best.
Now it has no effect on engine temp, but I have to say it’s
not as efficiant. But still good to a bit over mid 30s C .
Personally I think air con has to be in front blowing heaps
of air right at you. I think a couple of manufactures may have
had air con in the rear parcel shelf as standard [a Toyota
with two , one at front and one at rear] but the fact it hasn’t
caught on should be an indication hat it’s not the best way to
go.–
The original message included these comments:
on this item. I thought It could go in the trunk but they
mention an aera with a lot of air flow.
In reply to a message from Ed Nantes sent Fri 21 Aug 2015:
I’ve wondered about that. The older cars with rear
evaporators (Jaguar, 50’s Cadillacs for example) worked
pretty well according to what I’ve heard (I grew up with the
Caddy AC in Houston, and it was great). But in those days,
packaging the evaporator behind the fascia was difficult,
meaning that the evaporator had to be small. The (rear) evap
from a Mark X is about 3X as large as the (front) evap from
a S1 XJ6 (the first attempt at front evaps by Jaguar).
I think that blowing air in your face is a substitute for
actually air conditioning the cabin, as you would a room in
a house. This is evident if you are sitting in the back seat
(even if there is a vent back there, it doesn’t blow in your
face).
On my ‘‘list’’ is fitting a Mark X rear evaporator to my XJ6,
leaving the front one there as well. The GM A6 compressor
can easily supply both simultaneously.–
The original message included these comments:
Personally I think air con has to be in front blowing heaps
of air right at you. I think a couple of manufactures may have
had air con in the rear parcel shelf as standard [a Toyota
with two , one at front and one at rear] but the fact it hasn’t
caught on should be an indication hat it’s not the best way to
go.
In reply to a message from The Jag Man sent Tue 18 Aug 2015:
I couldn’t find the full spec sheet on this unit, but 6,613
BTU/hr is not enough to cool even a small car. Your average
mid-size SUV has a cooling unit with a 19-20,000 BTU capacity,
so I don’t know if this is suitable for any Jaguar.
Note that the unit runs from 9-30 volts. I would be interested
to know if the 25 amp draw is at 12 volts. I suspect the 25 amp
figure is at 30 volts. 12 volts might increase the amp draw to
60+ amps. If it drew 25 amps at 12 volts for 6,600 BTU/hr, that
would be pretty good - might be enough to cool a Mini.
But ultimately, it’s less efficient to convert mechanical power
to electrical power (crank to alternator) then convert it back
to mechanical energy (drive the compressor.) With current
technology, it only seems to make sense if the car has a high
voltage system (like a Prius with 48 volts) or as an auxiliary
unit for an enclosed area far from the engine drive space (like
a camper or van back area with low glass area and lots of
generating capacity.)
And as pointed out, the condensor has to go somewhere with
airflow to permit the heat to be radiated out of the
refrigerant. Perhaps someday when cooling technologies become
more power efficient (giant Peltier units?)–
The original message included these comments:
Just got my monthly Jegs catalog and they are featuring
their electric a/c unit. It does draw a lot of amps but
might be the perfect thing to avoid many of the pitfalls I
read about here with space, brackets and location of
condenser. Looking for feedback both positive and negative
on this item. I thought It could go in the trunk but they
mention an aera with a lot of air flow. http://www.jegs.com/i/JEGS-Performance-Products/555/51812/10002/-1?parentProductId=#moreDetails
Gerard
In reply to a message from bdragon sent Wed 26 Aug 2015:
Have a look at the interesting approach to cooling the
condenser located in the drivers side (for USA) fender well.
It is a faux sort of grill like on the 420 models but this
one is in working order. I think I would have balanced the
front of the car by adding a functional venting grill to the
other side which could have been used for engine or brake
cooling purposes:
Looks like the electric a/c models are just not up the job
of cooling like a engine driven mechanical unit
Gerard–
The original message included these comments:
And as pointed out, the condensor has to go somewhere with
airflow to permit the heat to be radiated out of the
refrigerant. Perhaps someday when cooling technologies become
As the former principal of RetroAir, we investigated the Electric Compressors thoroughly!
The ones Jegs sells would be for a very small car and, probably, be disappointing at any temperatures above 80 deg F. The one that would work for the average Sedan would require a huge electrical system as well as compatible Evaporator, Condenser and ancillary items. I understand that the Prius has a 450 Volt sytem to run their system??
Rock Browning
