I have no idea how yours works but if a
clutch solenoid (on a belt driven compressor) is experiencing low resistance
for what ever reason, sometimes it’ll blow the breaker, sometimes not. You
can measure the resistance of the clutch solenoid with an ohm meter when
disconnected from battery. Look for more than 5-6 ohms on the solenoid. If it’s
a direct drive compressor without a clutch, sorry … I’ve wasted
your time.
Jim
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf
Of Robert R Pastusek
Sent: Wednesday, August 03, 2011
3:57 PM
To: lml@lancaironline.net
Subject: [LML] Re: This is
puzzling ..and not only me...
This is puzzling me
and some others that I asked as well. Here is the thing.
When I switch on my AC
and it starts kicking in my amps goes up until 60 amps and than usually settles
around 43 amps. Which is fine I have a 100 amp alternator. Then I start my taxi
and the amps pretty much stays the same (with AC on).
But when I am doing a
run-up my amps goes all the way to 85amps…hovers there a little and then
settles back to around 70amp @ 1700rpm
In flight when the AC
is running (cruise) my amps are around 44amps. Sometimes it goes to 60amps,
this is when the AC kicks in again.
The puzzling part is,
why it goes all the way to 85amps and than goes back again on the run up? I
hope to trigger some Ideas here.
I am having problems
that my breaker from the AC pops after about 15-20min after start.
I will speculate
that you are drawing more power from the battery just after start than the
alternator can produce at idle RPM. This discharges the battery during warm
up/taxi. When you run up the engine, the alternator output increases to the max
allowed by the regulator for a short time until the battery recovers some of
its lost charge, then the regulator reduces the output somewhat to cover the
A/C load, plus other accessories and some to continue to re-charge the battery.
The in-flight
amerage represents the “steady state” load to carry your A/C and
other powered accessories, plus a “trickle charge” for the battery.
BTW, it sounds like you have an electrically-driven A/C compressor? I ask this
because this is significantly more amperage than an engine-driven compressor
based system should draw (mine uses about 12 amps with all components running;
less when the condenser fans are off (normal ops).
Enough for
“triggering ideas.” I’d contact the A/C manufacturer to see
what the starting and steady-state electrical loads should be. Don’t be
tempted to just change out the circuit breaker for a larger one…this is a
seriously bad idea until you confirm that the system, and especially the
wiring, can handle the higher current.
Bob